Ross (OCT, 1964) · Jenkinson (1928)
Greek line numbers are exact. The translations carry no Bekker numbers of their own, so those beside the English are aligned to the Greek: upright = fixed (anchored to this point in the text), italic grey = approximate (interpolated estimate).
Book 1,Chapter 1 (24a10–24b30)
24a
10 Πρῶτον εἰπεῖν περὶ τί καὶ τίνος ἐστὶν ἡ σκέψις, ὅτι περὶ
ἀπόδειξιν καὶ ἐπιστήμης ἀποδεικτικῆς· εἶτα διορίσαι τί
ἐστι πρότασις καὶ τί ὅρος καὶ τί συλλογισμός, καὶ ποῖος
τέλειος καὶ ποῖος ἀτελής, μετὰ δὲ ταῦτα τί τὸ ἐν ὅλῳ εἶναι
ἢ μὴ εἶναι τόδε τῷδε, καὶ τί λέγομεν τὸ κατὰ παντὸς
15 ἢ μηδενὸς κατηγορεῖσθαι.
Πρότασις μὲν οὖν ἐστὶ λόγος καταφατικὸς ἢ ἀποφατικός
τινος κατά τινος· οὗτος δὲ ἢ καθόλου ἢ ἐν μέρει ἢ ἀδιόριστος.
λέγω δὲ καθόλου μὲν τὸ παντὶ ἢ μηδενὶ ὑπάρχειν, ἐν μέρει
δὲ τὸ τινὶ ἢ μὴ τινὶ ἢ μὴ παντὶ ὑπάρχειν, ἀδιόριστον δὲ τὸ
20 ὑπάρχειν ἢ μὴ ὑπάρχειν ἄνευ τοῦ καθόλου ἢ κατὰ μέρος, οἷον
τὸ τῶν ἐναντίων εἶναι τὴν αὐτὴν ἐπιστήμην ἢ τὸ τὴν ἡδονὴν μὴ εἶναι
ἀγαθόν. διαφέρει δὲ ἡ ἀποδεικτικὴ πρότασις τῆς διαλεκτικῆς,
ὅτι ἡ μὲν ἀποδεικτικὴ λῆψις θατέρου μορίου τῆς ἀντιφάσεώς
ἐστιν (οὐ γὰρ ἐρωτᾷ ἀλλὰ λαμβάνει ὁ ἀποδεικνύων), ἡ δὲ
25 διαλεκτικὴ ἐρώτησις ἀντιφάσεώς ἐστιν. οὐδὲν δὲ διοίσει πρὸς τὸ
γενέσθαι τὸν ἑκατέρου συλλογισμόν· καὶ γὰρ ὁ ἀποδεικνύων
καὶ ὁ ἐρωτῶν συλλογίζεται λαβών τι κατά τινος ὑπάρχειν
ἢ μὴ ὑπάρχειν. ὥστε ἔσται συλλογιστικὴ μὲν πρότασις ἁπλῶς
κατάφασις ἢ ἀπόφασίς τινος κατά τινος τὸν εἰρημένον τρόπον,
30 ἀποδεικτικὴ δέ, ἐὰν ἀληθὴς ᾖ καὶ διὰ τῶν ἐξ ἀρχῆς
10We must first state the subject of our inquiry and the faculty to which it belongs: its subject is demonstration and the faculty that carries it out demonstrative science. We must next define a premiss, a term, and a syllogism, and the nature of a perfect and of an imperfect syllogism; and after that, the inclusion or noninclusion of one term in another as in a whole, and what we mean by predicating one term of all, 15or none, of another.
A premiss then is a sentence affirming or denying one thing of another. This is either universal or particular or indefinite. By universal I mean the statement that something belongs to all or none of something else; by particular that it belongs to some or not to some or not to all; by indefinite 20that it does or does not belong, without any mark to show whether it is universal or particular, e.g. 'contraries are subjects of the same science', or 'pleasure is not good'. The demonstrative premiss differs from the dialectical, because the demonstrative premiss is the assertion of one of two contradictory statements (the demonstrator does not ask for his premiss, but lays it down), 25whereas the dialectical premiss depends on the adversary's choice between two contradictories. 30But this will make no difference to the production of a syllogism in either case; for both the demonstrator and the dialectician argue syllogistically after stating that something does or does not belong to something else.
A premiss then is a sentence affirming or denying one thing of another. This is either universal or particular or indefinite. By universal I mean the statement that something belongs to all or none of something else; by particular that it belongs to some or not to some or not to all; by indefinite 20that it does or does not belong, without any mark to show whether it is universal or particular, e.g. 'contraries are subjects of the same science', or 'pleasure is not good'. The demonstrative premiss differs from the dialectical, because the demonstrative premiss is the assertion of one of two contradictory statements (the demonstrator does not ask for his premiss, but lays it down), 25whereas the dialectical premiss depends on the adversary's choice between two contradictories. 30But this will make no difference to the production of a syllogism in either case; for both the demonstrator and the dialectician argue syllogistically after stating that something does or does not belong to something else.
24b
10 ὑποθέσεων εἰλημμένη, διαλεκτικὴ δὲ πυνθανομένῳ μὲν ἐρώτησις
ἀντιφάσεως, συλλογιζομένῳ δὲ λῆψις τοῦ φαινομένου
καὶ ἐνδόξου, καθάπερ ἐν τοῖς Τοπικοῖς εἴρηται. τί μὲν οὖν ἐστὶ
πρότασις, καὶ τί διαφέρει συλλογιστικὴ καὶ ἀποδεικτικὴ καὶ
διαλεκτική, δι' ἀκριβείας μὲν ἐν τοῖς ἑπομένοις ῥηθήσεται,
15 πρὸς δὲ τὴν παροῦσαν χρείαν ἱκανῶς ἡμῖν διωρίσθω τὰ νῦν.
Ὅρον δὲ καλῶ εἰς ὃν διαλύεται ἡ πρότασις, οἷον τό τε κατηγορούμενον
καὶ τὸ καθ' οὗ κατηγορεῖται, προστιθεμένου [ἢ διαιρουμένου]
τοῦ εἶναι ἢ μὴ εἶναι. συλλογισμὸς δέ ἐστι λόγος ἐν
ᾧ τεθέντων τινῶν ἕτερόν τι τῶν κειμένων ἐξ ἀνάγκης συμβαίνει
20 τῷ ταῦτα εἶναι. λέγω δὲ τῷ ταῦτα εἶναι τὸ διὰ ταῦτα
συμβαίνειν, τὸ δὲ διὰ ταῦτα συμβαίνειν τὸ μηδενὸς ἔξωθεν
ὅρου προσδεῖν πρὸς τὸ γενέσθαι τὸ ἀναγκαῖον. τέλειον μὲν οὖν
καλῶ συλλογισμὸν τὸν μηδενὸς ἄλλου προσδεόμενον παρὰ τὰ
εἰλημμένα πρὸς τὸ φανῆναι τὸ ἀναγκαῖον, ἀτελῆ δὲ τὸν προςδεόμενον
25 ἢ ἑνὸς ἢ πλειόνων, ἃ ἔστι μὲν ἀναγκαῖα διὰ τῶν
ὑποκειμένων ὅρων, οὐ μὴν εἴληπται διὰ προτάσεων. τὸ δὲ ἐν
ὅλῳ εἶναι ἕτερον ἑτέρῳ καὶ τὸ κατὰ παντὸς κατηγορεῖσθαι
θατέρου θάτερον ταὐτόν ἐστιν. λέγομεν δὲ τὸ κατὰ παντὸς
κατηγορεῖσθαι ὅταν μηδὲν ᾖ λαβεῖν [τοῦ ὑποκειμένου]
30 καθ' οὗ θάτερον οὐ λεχθήσεται· καὶ τὸ κατὰ μηδενὸς ὡσαύτως.
Therefore a syllogistic premiss without qualification will be an affirmation or denial of something concerning something else in the way we have described; it will be demonstrative, if it is true and obtained through the first 10principles of its science; while a dialectical premiss is the giving of a choice between two contradictories, when a man is proceeding by question, but when he is syllogizing it is the assertion of that which is apparent and generally admitted, as has been said in the Topics. The nature then of a premiss and the difference between syllogistic, demonstrative, and dialectical premisses, 15may be taken as sufficiently defined by us in relation to our present need, but will be stated accurately in the sequel.
I call that a term into which the premiss is resolved, i.e. both the predicate and that of which it is predicated, 'being' being added and 'not being' removed, or vice versa.
A syllogism is discourse in which, certain things being stated, something other than what is stated 20follows of necessity from their being so. I mean by the last phrase that they produce the consequence, and by this, that no further term is required from without in order to make the consequence necessary.
I call that a perfect syllogism which needs nothing other than what has been stated to make plain what necessarily follows; a syllogism is imperfect, 25if it needs either one or more propositions, which are indeed the necessary consequences of the terms set down, but have not been expressly stated as premisses.
That one term should be included in another as in a whole is the same as for the other to be predicated of all of the first. And we say that one term is predicated of all of another, whenever no instance of the subject can be found 30of which the other term cannot be asserted: 'to be predicated of none' must be understood in the same way.
I call that a term into which the premiss is resolved, i.e. both the predicate and that of which it is predicated, 'being' being added and 'not being' removed, or vice versa.
A syllogism is discourse in which, certain things being stated, something other than what is stated 20follows of necessity from their being so. I mean by the last phrase that they produce the consequence, and by this, that no further term is required from without in order to make the consequence necessary.
I call that a perfect syllogism which needs nothing other than what has been stated to make plain what necessarily follows; a syllogism is imperfect, 25if it needs either one or more propositions, which are indeed the necessary consequences of the terms set down, but have not been expressly stated as premisses.
That one term should be included in another as in a whole is the same as for the other to be predicated of all of the first. And we say that one term is predicated of all of another, whenever no instance of the subject can be found 30of which the other term cannot be asserted: 'to be predicated of none' must be understood in the same way.
Book 1,Chapter 2 (25a1–26)
25a
1 Ἐπεὶ δὲ πᾶσα πρότασίς ἐστιν ἢ τοῦ ὑπάρχειν ἢ τοῦ ἐξ
ἀνάγκης ὑπάρχειν ἢ τοῦ ἐνδέχεσθαι ὑπάρχειν, τούτων δὲ αἱ
μὲν καταφατικαὶ αἱ δὲ ἀποφατικαὶ καθ' ἑκάστην πρόσρησιν,
πάλιν δὲ τῶν καταφατικῶν καὶ ἀποφατικῶν αἱ μὲν καθόλου
5 αἱ δὲ ἐν μέρει αἱ δὲ ἀδιόριστοι, τὴν μὲν ἐν τῷ ὑπάρχειν καθόλου
στερητικὴν ἀνάγκη τοῖς ὅροις ἀντιστρέφειν, οἷον εἰ μηδεμία
ἡδονὴ ἀγαθόν, οὐδ' ἀγαθὸν οὐδὲν ἔσται ἡδονή· τὴν δὲ κατηγορικὴν
ἀντιστρέφειν μὲν ἀναγκαῖον, οὐ μὴν καθόλου ἀλλ' ἐν
μέρει, οἷον εἰ πᾶσα ἡδονὴ ἀγαθόν, καὶ ἀγαθόν τι εἶναι ἡδονήν·
10 τῶν δὲ ἐν μέρει τὴν μὲν καταφατικὴν ἀντιστρέφειν ἀνάγκη
κατὰ μέρος (εἰ γὰρ ἡδονή τις ἀγαθόν, καὶ ἀγαθόν τι ἔσται
ἡδονή), τὴν δὲ στερητικὴν οὐκ ἀναγκαῖον· (οὐ γὰρ εἰ ἄνθρωπος
μὴ ὑπάρχει τινὶ ζῴῳ, καὶ ζῷον οὐχ ὑπάρχει τινὶ ἀνθρώπῳ).
Πρῶτον μὲν οὖν ἔστω στερητικὴ καθόλου ἡ Α Β πρότασις.
15 εἰ οὖν μηδενὶ τῷ Β τὸ Α ὑπάρχει, οὐδὲ τῷ Α οὐδενὶ ὑπάρξει
τὸ Β· εἰ γάρ τινι, οἷον τῷ Γ, οὐκ ἀληθὲς ἔσται τὸ μηδενὶ τῷ
Β τὸ Α ὑπάρχειν· τὸ γὰρ Γ τῶν Β τί ἐστιν. εἰ δὲ παντὶ τὸ
Α τῷ Β, καὶ τὸ Β τινὶ τῷ Α ὑπάρξει· εἰ γὰρ μηδενί, οὐδὲ
τὸ Α οὐδενὶ τῷ Β ὑπάρξει· ἀλλ' ὑπέκειτο παντὶ ὑπάρχειν.
20 ὁμοίως δὲ καὶ εἰ κατὰ μέρος ἐστὶν ἡ πρότασις. εἰ γὰρ τὸ Α
τινὶ τῷ Β, καὶ τὸ Β τινὶ τῷ Α ἀνάγκη ὑπάρχειν· εἰ γὰρ
μηδενί, οὐδὲ τὸ Α οὐδενὶ τῷ Β. εἰ δέ γε τὸ Α τινὶ
τῷ Β μὴ ὑπάρχει, οὐκ ἀνάγκη καὶ τὸ Β τινὶ τῷ Α μὴ
ὑπάρχειν, οἷον εἰ τὸ μὲν Β ἐστὶ ζῷον, τὸ δὲ Α ἄνθρωπος·
25 ἄνθρωπος μὲν γὰρ οὐ παντὶ ζῴῳ, ζῷον δὲ παντὶ ἀνθρώπῳ
ὑπάρχει.
1Every premiss states that something either is or must be or may be the attribute of something else; of premisses of these three kinds some are affirmative, others negative, in respect of each of the three modes of attribution; again some affirmative and negative premisses are universal, 5others particular, others indefinite. It is necessary then that in universal attribution the terms of the negative premiss should be convertible, e.g. if no pleasure is good, then no good will be pleasure; the terms of the affirmative must be convertible, not however, universally, but in part, e.g. if every pleasure,is good, some good must be pleasure; 10the particular affirmative must convert in part (for if some pleasure is good, then some good will be pleasure); but the particular negative need not convert, for if some animal is not man, it does not follow that some man is not animal.
First then take a universal negative with the terms A and B. 15If no B is A, neither can any A be B. For if some A (say C) were B, it would not be true that no B is A; for C is a B. But if every B is A then some A is B. For if no A were B, then no B could be A. But we assumed that every B is A. 20Similarly too, if the premiss is particular. For if some B is A, then some of the As must be B. For if none were, then no B would be A. But if some B is not A, there is no necessity that some of the As should not be B; e.g. let B stand for animal and A for man. 25Not every animal is a man; but every man is an animal.
First then take a universal negative with the terms A and B. 15If no B is A, neither can any A be B. For if some A (say C) were B, it would not be true that no B is A; for C is a B. But if every B is A then some A is B. For if no A were B, then no B could be A. But we assumed that every B is A. 20Similarly too, if the premiss is particular. For if some B is A, then some of the As must be B. For if none were, then no B would be A. But if some B is not A, there is no necessity that some of the As should not be B; e.g. let B stand for animal and A for man. 25Not every animal is a man; but every man is an animal.
Book 1,Chapter 3 (25a27–25b25)
Τὸν αὐτὸν δὲ τρόπον ἕξει καὶ ἐπὶ τῶν ἀναγκαίων προτάσεων.
ἡ μὲν γὰρ καθόλου στερητικὴ καθόλου ἀντιστρέφει, τῶν
δὲ καταφατικῶν ἑκατέρα κατὰ μέρος. εἰ μὲν γὰρ ἀνάγκη
30 τὸ Α τῷ Β μηδενὶ ὑπάρχειν, ἀνάγκη καὶ τὸ Β τῷ Α μηδενὶ
ὑπάρχειν· εἰ γὰρ τινὶ ἐνδέχεται, καὶ τὸ Α τῷ Β τινὶ ἐνδέχοιτο
ἄν. εἰ δὲ ἐξ ἀνάγκης τὸ Α παντὶ ἢ τινὶ τῷ Β ὑπάρχει,
καὶ τὸ Β τινὶ τῷ Α ἀνάγκη ὑπάρχειν· εἰ γὰρ μὴ
ἀνάγκη, οὐδ' ἂν τὸ Α τινὶ τῷ Β ἐξ ἀνάγκης ὑπάρχοι. τὸ δ'
35 ἐν μέρει στερητικὸν οὐκ ἀντιστρέφει, διὰ τὴν αὐτὴν αἰτίαν δι' ἣν
καὶ πρότερον ἔφαμεν.
Ἐπὶ δὲ τῶν ἐνδεχομένων, ἐπειδὴ πολλαχῶς λέγεται
τὸ ἐνδέχεσθαι (καὶ γὰρ τὸ ἀναγκαῖον καὶ τὸ μὴ ἀναγκαῖον
καὶ τὸ δυνατὸν ἐνδέχεσθαι λέγομεν), ἐν μὲν τοῖς καταφατικοῖς
40 ὁμοίως ἕξει κατὰ τὴν ἀντιστροφὴν ἐν ἅπασιν. εἰ γὰρ τὸ Α
27The same manner of conversion will hold good also in respect of necessary premisses. The universal negative converts universally; each of the affirmatives converts into a particular. If it is necessary that no B is A, 30it is necessary also that no A is B. For if it is possible that some A is B, it would be possible also that some B is A. If all or some B is A of necessity, it is necessary also that some A is B: for if there were no necessity, neither would some of the Bs be A necessarily. But 35the particular negative does not convert, for the same reason which we have already stated.
In respect of possible premisses, since possibility is used in several senses (for we say that what is necessary and what is not necessary and what is potential is possible), 40affirmative statements will all convert in a manner similar to those described. For if it is possible that all or some B is A, it will be possible that some A is B. For if that were not possible, then no B could possibly be A.
In respect of possible premisses, since possibility is used in several senses (for we say that what is necessary and what is not necessary and what is potential is possible), 40affirmative statements will all convert in a manner similar to those described. For if it is possible that all or some B is A, it will be possible that some A is B. For if that were not possible, then no B could possibly be A.
25b
1 παντὶ ἢ τινὶ τῷ Β ἐνδέχεται, καὶ τὸ Β τινὶ τῷ Α ἐνδέχοιτο
ἄν· εἰ γὰρ μηδενί, οὐδ' ἂν τὸ Α οὐδενὶ τῷ Β· δέδεικται γὰρ
τοῦτο πρότερον. ἐν δὲ τοῖς ἀποφατικοῖς οὐχ ὡσαύτως, ἀλλ'
ὅσα μὲν ἐνδέχεσθαι λέγεται τῷ ἐξ ἀνάγκης ὑπάρχειν ἢ τῷ
5 μὴ ἐξ ἀνάγκης μὴ ὑπάρχειν, ὁμοίως, οἷον εἴ τις φαίη τὸν
ἄνθρωπον ἐνδέχεσθαι μὴ εἶναι ἵππον ἢ τὸ λευκὸν μηδενὶ ἱματίῳ
ὑπάρχειν (τούτων γὰρ τὸ μὲν ἐξ ἀνάγκης οὐχ ὑπάρχει,
τὸ δὲ οὐκ ἀνάγκη ὑπάρχειν, καὶ ὁμοίως ἀντιστρέφει ἡ πρότασις·
εἰ γὰρ ἐνδέχεται μηδενὶ ἀνθρώπῳ ἵππον, καὶ ἄνθρωπον
10 ἐγχωρεῖ μηδενὶ ἵππῳ· καὶ εἰ τὸ λευκὸν ἐγχωρεῖ μηδενὶ
ἱματίῳ, καὶ τὸ ἱμάτιον ἐγχωρεῖ μηδενὶ λευκῷ· εἰ γάρ τινι
ἀνάγκη, καὶ τὸ λευκὸν ἱματίῳ τινὶ ἔσται ἐξ ἀνάγκης· τοῦτο
γὰρ δέδεικται πρότερον), ὁμοίως δὲ καὶ ἐπὶ τῆς ἐν μέρει ἀποφατικῆς·
ὅσα δὲ τῷ ὡς ἐπὶ τὸ πολὺ καὶ τῷ πεφυκέναι λέγεται
15 ἐνδέχεσθαι, καθ' ὃν τρόπον διορίζομεν τὸ ἐνδεχόμενον, οὐχ
ὁμοίως ἕξει ἐν ταῖς στερητικαῖς ἀντιστροφαῖς, ἀλλ' ἡ μὲν καθόλου
στερητικὴ πρότασις οὐκ ἀντιστρέφει, ἡ δὲ ἐν μέρει ἀντιστρέφει.
τοῦτο δὲ ἔσται φανερὸν ὅταν περὶ τοῦ ἐνδεχομένου
λέγωμεν. νῦν δὲ τοσοῦτον ἡμῖν ἔστω πρὸς τοῖς εἰρημένοις δῆλον,
20 ὅτι τὸ ἐνδέχεσθαι μηδενὶ ἢ τινὶ μὴ ὑπάρχειν καταφατικὸν
ἔχει τὸ σχῆμα (τὸ γὰρ ἐνδέχεται τῷ ἔστιν ὁμοίως τάττεται,
τὸ δὲ ἔστιν, οἷς ἂν προσκατηγορῆται, κατάφασιν ἀεὶ
ποιεῖ καὶ πάντως, οἷον τὸ ἔστιν οὐκ ἀγαθόν ἢ ἔστιν οὐ λευκόν ἢ
ἁπλῶς τὸ ἔστιν οὐ τοῦτο· δειχθήσεται δὲ καὶ τοῦτο διὰ τῶν ἑπομένων),
25 κατὰ δὲ τὰς ἀντιστροφὰς ὁμοίως ἕξουσι ταῖς ἄλλαις.
1This has been already proved. But in negative statements the case is different. Whatever is said to be possible, either because B necessarily is A, or because 5B is not necessarily A, admits of conversion like other negative statements, e.g. if one should say, it is possible that man is not horse, or that no garment is white. For in the former case the one term necessarily does not belong to the other; in the latter there is no necessity that it should: and the premiss converts like other negative statements. For if it is possible for no man to be a horse, it is also admissible for no horse 10to be a man; and if it is admissible for no garment to be white, it is also admissible for nothing white to be a garment. For if any white thing must be a garment, then some garment will necessarily be white. This has been already proved. The particular negative also must be treated like those dealt with above. But if anything is said to be possible because it is the general rule and natural (15and it is in this way we define the possible), the negative premisses can no longer be converted like the simple negatives; the universal negative premiss does not convert, and the particular does. This will be plain when we speak about the possible. At present we may take this much as clear in addition to what has been said: 20the statement that it is possible that no B is A or some B is not A is affirmative in form: for the expression 'is possible' ranks along with 'is', and 'is' makes an affirmation always and in every case, whatever the terms to which it is added, in predication, e.g. 'it is not-good' or 'it is not-white' or in a word 'it is not-this'. But this also will be proved in the sequel. 25In conversion these premisses will behave like the other affirmative propositions.
Book 1,Chapter 4 (25b26–26b33)
Διωρισμένων δὲ τούτων λέγωμεν ἤδη διὰ τίνων καὶ πότε
καὶ πῶς γίνεται πᾶς συλλογισμός· ὕστερον δὲ λεκτέον περὶ
ἀποδείξεως. πρότερον δὲ περὶ συλλογισμοῦ λεκτέον ἢ περὶ
ἀποδείξεως διὰ τὸ καθόλου μᾶλλον εἶναι τὸν συλλογισμόν·
30 ἡ μὲν γὰρ ἀπόδειξις συλλογισμός τις, ὁ συλλογισμὸς δὲ
οὐ πᾶς ἀπόδειξις.
Ὅταν οὖν ὅροι τρεῖς οὕτως ἔχωσι πρὸς ἀλλήλους ὥστε τὸν
ἔσχατον ἐν ὅλῳ εἶναι τῷ μέσῳ καὶ τὸν μέσον ἐν ὅλῳ τῷ πρώτῳ
ἢ εἶναι ἢ μὴ εἶναι, ἀνάγκη τῶν ἄκρων εἶναι συλλογισμὸν
35 τέλειον. καλῶ δὲ μέσον μὲν ὃ καὶ αὐτὸ ἐν ἄλλῳ καὶ ἄλλο
ἐν τούτῳ ἐστίν, ὃ καὶ τῇ θέσει γίνεται μέσον· ἄκρα δὲ τὸ αὐτό
τε ἐν ἄλλῳ ὂν καὶ ἐν ᾧ ἄλλο ἐστίν. εἰ γὰρ τὸ Α κατὰ παντὸς
τοῦ Β καὶ τὸ Β κατὰ παντὸς τοῦ Γ, ἀνάγκη τὸ Α κατὰ
παντὸς τοῦ Γ κατηγορεῖσθαι· πρότερον γὰρ εἴρηται πῶς τὸ
40 κατὰ παντὸς λέγομεν. ὁμοίως δὲ καὶ εἰ τὸ μὲν Α κατὰ μηδενὸς
26After these distinctions we now state by what means, when, and how every syllogism is produced; subsequently we must speak of demonstration. Syllogism should be discussed before demonstration because syllogism is the general: 30the demonstration is a sort of syllogism, but not every syllogism is a demonstration.
Whenever three terms are so related to one another that the last is contained in the middle as in a whole, and the middle is either contained in, or excluded from, the first as in or from a whole, the extremes must be related by a perfect syllogism. 35I call that term middle which is itself contained in another and contains another in itself: in position also this comes in the middle. By extremes I mean both that term which is itself contained in another and that in which another is contained. If A is predicated of all B, and B of all C, A must be predicated of all C: we have already explained 40what we mean by 'predicated of all'. Similarly also, if A is predicated of no B, and B of all C, it is necessary that no C will be A.
Whenever three terms are so related to one another that the last is contained in the middle as in a whole, and the middle is either contained in, or excluded from, the first as in or from a whole, the extremes must be related by a perfect syllogism. 35I call that term middle which is itself contained in another and contains another in itself: in position also this comes in the middle. By extremes I mean both that term which is itself contained in another and that in which another is contained. If A is predicated of all B, and B of all C, A must be predicated of all C: we have already explained 40what we mean by 'predicated of all'. Similarly also, if A is predicated of no B, and B of all C, it is necessary that no C will be A.
26a
1 τοῦ Β, τὸ δὲ Β κατὰ παντὸς τοῦ Γ, ὅτι τὸ Α οὐδενὶ τῷ
Γ ὑπάρξει. εἰ δὲ τὸ μὲν πρῶτον παντὶ τῷ μέσῳ ἀκολουθεῖ,
τὸ δὲ μέσον μηδενὶ τῷ ἐσχάτῳ ὑπάρχει, οὐκ ἔσται συλλογισμὸς
τῶν ἄκρων· οὐδὲν γὰρ ἀναγκαῖον συμβαίνει τῷ ταῦτα
5 εἶναι· καὶ γὰρ παντὶ καὶ μηδενὶ ἐνδέχεται τὸ πρῶτον τῷ
ἐσχάτῳ ὑπάρχειν, ὥστε οὔτε τὸ κατὰ μέρος οὔτε τὸ καθόλου γίνεται
ἀναγκαῖον· μηδενὸς δὲ ὄντος ἀναγκαίου διὰ τούτων οὐκ
ἔσται συλλογισμός. ὅροι τοῦ παντὶ ὑπάρχειν ζῷον—ἄνθρωπος—
ἵππος, τοῦ μηδενὶ ζῷον—ἄνθρωπος—λίθος. οὐδ' ὅταν μήτε τὸ
10 πρῶτον τῷ μέσῳ μήτε τὸ μέσον τῷ ἐσχάτῳ μηδενὶ ὑπάρχῃ,
οὐδ' οὕτως ἔσται συλλογισμός. ὅροι τοῦ ὑπάρχειν ἐπιστήμη—
γραμμή—ἰατρική, τοῦ μὴ ὑπάρχειν ἐπιστήμη—γραμμή—μονάς.
καθόλου μὲν οὖν ὄντων τῶν ὅρων, δῆλον ἐν τούτῳ τῷ σχήματι
πότε ἔσται καὶ πότε οὐκ ἔσται συλλογισμός, καὶ ὅτι ὄντος
15 τε συλλογισμοῦ τοὺς ὅρους ἀναγκαῖον ἔχειν ὡς εἴπομεν,
ἄν θ' οὕτως ἔχωσιν, ὅτι ἔσται συλλογισμός.
Εἰ δ' ὁ μὲν καθόλου τῶν ὅρων ὁ δ' ἐν μέρει πρὸς τὸν ἕτερον,
ὅταν μὲν τὸ καθόλου τεθῇ πρὸς τὸ μεῖζον ἄκρον ἢ κατηγορικὸν ἢ
στερητικόν, τὸ δὲ ἐν μέρει πρὸς τὸ ἔλαττον κατηγορικόν, ἀνάγκη
20 συλλογισμὸν εἶναι τέλειον, ὅταν δὲ πρὸς τὸ ἔλαττον ἢ
καὶ ἄλλως πως ἔχωσιν οἱ ὅροι, ἀδύνατον. λέγω δὲ μεῖζον
μὲν ἄκρον ἐν ᾧ τὸ μέσον ἐστίν, ἔλαττον δὲ τὸ ὑπὸ τὸ μέσον
ὄν. ὑπαρχέτω γὰρ τὸ μὲν Α παντὶ τῷ Β, τὸ δὲ Β τινὶ τῷ Γ.
οὐκοῦν εἰ ἔστι παντὸς κατηγορεῖσθαι τὸ ἐν ἀρχῇ λεχθέν, ἀνάγκη
25 τὸ Α τινὶ τῷ Γ ὑπάρχειν. καὶ εἰ τὸ μὲν Α μηδενὶ τῷ Β
ὑπάρχει, τὸ δὲ Β τινὶ τῷ Γ, ἀνάγκη τὸ Α τινὶ τῷ Γ μὴ
ὑπάρχειν· ὥρισται γὰρ καὶ τὸ κατὰ μηδενὸς πῶς λέγομεν·
ὥστε ἔσται συλλογισμὸς τέλειος. ὁμοίως δὲ καὶ εἰ ἀδιόριστον
εἴη τὸ Β Γ, κατηγορικὸν ὄν· ὁ γὰρ αὐτὸς ἔσται συλλογισμὸς
30 ἀδιορίστου τε καὶ ἐν μέρει ληφθέντος. Ἐὰν δὲ πρὸς τὸ ἔλαττον
ἄκρον τὸ καθόλου τεθῇ ἢ κατηγορικὸν ἢ στερητικόν, οὐκ ἔσται
συλλογισμός, οὔτε καταφατικοῦ οὔτε ἀποφατικοῦ τοῦ ἀδιορίστου
ἢ κατὰ μέρος ὄντος, οἷον εἰ τὸ μὲν Α τινὶ τῷ Β ὑπάρχει
ἢ μὴ ὑπάρχει, τὸ δὲ Β παντὶ τῷ Γ ὑπάρχει· ὅροι τοῦ
35 ὑπάρχειν ἀγαθόν—ἕξις—φρόνησις, τοῦ μὴ ὑπάρχειν ἀγαθόν—ἕξις—
ἀμαθία. πάλιν εἰ τὸ μὲν Β μηδενὶ τῷ Γ, τὸ δὲ Α τινὶ τῷ Β ἢ
ὑπάρχει ἢ μὴ ὑπάρχει ἢ μὴ παντὶ ὑπάρχει, οὐδ' οὕτως ἔσται
συλλογισμός. ὅροι λευκόν—ἵππος—κύκνος, λευκόν—ἵππος—κόραξ.
οἱ αὐτοὶ δὲ καὶ εἰ τὸ Α Β ἀδιόριστον. Οὐδ' ὅταν τὸ μὲν πρὸς
1But if the first term belongs to all the middle, but the middle to none of the last term, there will be no syllogism in respect of the extremes; for nothing necessary follows from the terms 5being so related; for it is possible that the first should belong either to all or to none of the last, so that neither a particular nor a universal conclusion is necessary. But if there is no necessary consequence, there cannot be a syllogism by means of these premisses. As an example of a universal affirmative relation between the extremes we may take the terms animal, man, horse; of a universal negative relation, the terms animal, man, stone. Nor again can syllogism be formed when 10neither the first term belongs to any of the middle, nor the middle to any of the last. As an example of a positive relation between the extremes take the terms science, line, medicine: of a negative relation science, line, unit.
If then the terms are universally related, it is clear in this figure when a syllogism will be possible and when not, and that 15if a syllogism is possible the terms must be related as described, and if they are so related there will be a syllogism.
But if one term is related universally, the other in part only, to its subject, there must be a perfect syllogism whenever universality is posited with reference to the major term either affirmatively or negatively, and particularity with reference to the minor term affirmatively: 20but whenever the universality is posited in relation to the minor term, or the terms are related in any other way, a syllogism is impossible. I call that term the major in which the middle is contained and that term the minor which comes under the middle. Let all B be A and some C be B. Then if 'predicated of all' means what was said above, 25it is necessary that some C is A. And if no B is A but some C is B, it is necessary that some C is not A. The meaning of 'predicated of none' has also been defined. So there will be a perfect syllogism. This holds good also if the premiss BC should be indefinite, provided that it is affirmative: for we shall have the same syllogism 30whether the premiss is indefinite or particular.
But if the universality is posited with respect to the minor term either affirmatively or negatively, a syllogism will not be possible, whether the major premiss is positive or negative, indefinite or particular: e.g. if some B is or is not A, and all C is B. As an example of a positive relation between the extremes take the terms 35good, state, wisdom: of a negative relation, good, state, ignorance. Again if no C is B, but some B is or is not A or not every B is A, there cannot be a syllogism.
If then the terms are universally related, it is clear in this figure when a syllogism will be possible and when not, and that 15if a syllogism is possible the terms must be related as described, and if they are so related there will be a syllogism.
But if one term is related universally, the other in part only, to its subject, there must be a perfect syllogism whenever universality is posited with reference to the major term either affirmatively or negatively, and particularity with reference to the minor term affirmatively: 20but whenever the universality is posited in relation to the minor term, or the terms are related in any other way, a syllogism is impossible. I call that term the major in which the middle is contained and that term the minor which comes under the middle. Let all B be A and some C be B. Then if 'predicated of all' means what was said above, 25it is necessary that some C is A. And if no B is A but some C is B, it is necessary that some C is not A. The meaning of 'predicated of none' has also been defined. So there will be a perfect syllogism. This holds good also if the premiss BC should be indefinite, provided that it is affirmative: for we shall have the same syllogism 30whether the premiss is indefinite or particular.
But if the universality is posited with respect to the minor term either affirmatively or negatively, a syllogism will not be possible, whether the major premiss is positive or negative, indefinite or particular: e.g. if some B is or is not A, and all C is B. As an example of a positive relation between the extremes take the terms 35good, state, wisdom: of a negative relation, good, state, ignorance. Again if no C is B, but some B is or is not A or not every B is A, there cannot be a syllogism.
26b
1 τῷ μείζονι ἄκρῳ καθόλου γένηται ἢ κατηγορικὸν ἢ στερητικόν,
τὸ δὲ πρὸς τῷ ἐλάττονι στερητικὸν κατὰ μέρος, οὐκ ἔσται συλλογισμός
[ἀδιορίστου τε καὶ ἐν μέρει ληφθέντος], οἷον εἰ τὸ μὲν
Α παντὶ τῷ Β ὑπάρχει, τὸ δὲ Β τινὶ τῷ Γ μή, ἢ εἰ μὴ
5 παντὶ ὑπάρχει· ᾧ γὰρ ἄν τινι μὴ ὑπάρχῃ τὸ μέσον, τούτῳ
καὶ παντὶ καὶ οὐδενὶ ἀκολουθήσει τὸ πρῶτον. ὑποκείσθωσαν
γὰρ οἱ ὅροι ζῷον—ἄνθρωπος—λευκόν· εἶτα καὶ ὧν μὴ κατηγορεῖται
λευκῶν ὁ ἄνθρωπος, εἰλήφθω κύκνος καὶ χιών·
οὐκοῦν τὸ ζῷον τοῦ μὲν παντὸς κατηγορεῖται, τοῦ δὲ οὐδενός, ὥστε
10 οὐκ ἔσται συλλογισμός. πάλιν τὸ μὲν Α μηδενὶ τῷ Β ὑπαρχέτω,
τὸ δὲ Β τινὶ τῷ Γ μὴ ὑπαρχέτω· καὶ οἱ ὅροι ἔστωσαν
ἄψυχον—ἄνθρωπος—λευκόν· εἶτα εἰλήφθωσαν, ὧν μὴ κατηγορεῖται
λευκῶν ὁ ἄνθρωπος, κύκνος καὶ χιών· τὸ γὰρ ἄψυχον
τοῦ μὲν παντὸς κατηγορεῖται, τοῦ δὲ οὐδενός. ἔτι ἐπεὶ ἀδιόριστον
15 τὸ τινὶ τῷ Γ τὸ Β μὴ ὑπάρχειν, ἀληθεύεται δέ, καὶ
εἰ μηδενὶ ὑπάρχει καὶ εἰ μὴ παντί, ὅτι τινὶ οὐχ ὑπάρχει,
ληφθέντων δὲ τοιούτων ὅρων ὥστε μηδενὶ ὑπάρχειν οὐ γίνεται
συλλογισμός (τοῦτο γὰρ εἴρηται πρότερον), φανερὸν οὖν ὅτι
τῷ οὕτως ἔχειν τοὺς ὅρους οὐκ ἔσται συλλογισμός· ἦν γὰρ ἂν
20 καὶ ἐπὶ τούτων. ὁμοίως δὲ δειχθήσεται καὶ εἰ τὸ καθόλου
τεθείη στερητικόν. Οὐδὲ ἐὰν ἄμφω τὰ διαστήματα κατὰ μέρος
ἢ κατηγορικῶς ἢ στερητικῶς, ἢ τὸ μὲν κατηγορικῶς τὸ δὲ
στερητικῶς λέγηται, ἢ τὸ μὲν ἀδιόριστον τὸ δὲ διωρισμένον, ἢ
ἄμφω ἀδιόριστα, οὐκ ἔσται συλλογισμὸς οὐδαμῶς. ὅροι δὲ κοινοὶ
25 πάντων ζῷον—λευκόν—ἵππος, ζῷον—λευκόν—λίθος.
Φανερὸν οὖν ἐκ τῶν εἰρημένων ὡς ἐὰν ᾖ συλλογισμὸς ἐν
τούτῳ τῷ σχήματι κατὰ μέρος, ὅτι ἀνάγκη τοὺς ὅρους οὕτως
ἔχειν ὡς εἴπομεν· ἄλλως γὰρ ἐχόντων οὐδαμῶς γίνεται. δῆλον
δὲ καὶ ὅτι πάντες οἱ ἐν αὐτῷ συλλογισμοὶ τέλειοί εἰσι·
30 (πάντες γὰρ ἐπιτελοῦνται διὰ τῶν ἐξ ἀρχῆς ληφθέντων), καὶ ὅτι
πάντα τὰ προβλήματα δείκνυται διὰ τούτου τοῦ σχήματος·
καὶ γὰρ τὸ παντὶ καὶ τὸ μηδενὶ καὶ τὸ τινὶ καὶ τὸ μή τινι
ὑπάρχειν. καλῶ δὲ τὸ τοιοῦτον σχῆμα πρῶτον.
1Take the terms white, horse, swan: white, horse, raven. The same terms may be taken also if the premiss BA is indefinite.
Nor when the major premiss is universal, whether affirmative or negative, and the minor premiss is negative and particular, can there be a syllogism, whether the minor premiss be indefinite or particular: e.g. if all B is A and some C is not B, or 5if not all C is B. For the major term may be predicable both of all and of none of the minor, to some of which the middle term cannot be attributed. Suppose the terms are animal, man, white: next take some of the white things of which man is not predicated-swan and snow: animal is predicated of all of the one, but of none of the other. 10Consequently there cannot be a syllogism. Again let no B be A, but let some C not be B. Take the terms inanimate, man, white: then take some white things of which man is not predicated-swan and snow: the term inanimate is predicated of all of the one, of none of the other.
Further 15since it is indefinite to say some C is not B, and it is true that some C is not B, whether no C is B, or not all C is B, and since if terms are assumed such that no C is B, no syllogism follows (this has already been stated) it is clear that this arrangement of terms will not afford a syllogism: otherwise one would have been possible with a universal negative minor premiss. 20A similar proof may also be given if the universal premiss is negative.
Nor can there in any way be a syllogism if both the relations of subject and predicate are particular, either positively or negatively, or the one negative and the other affirmative, or one indefinite and the other definite, or both indefinite. 25Terms common to all the above are animal, white, horse: animal, white, stone.
It is clear then from what has been said that if there is a syllogism in this figure with a particular conclusion, the terms must be related as we have stated: if they are related otherwise, no syllogism is possible anyhow. It is evident also that all the syllogisms in this figure are perfect 30(for they are all completed by means of the premisses originally taken) and that all conclusions are proved by this figure, viz. universal and particular, affirmative and negative. Such a figure I call the first.
Nor when the major premiss is universal, whether affirmative or negative, and the minor premiss is negative and particular, can there be a syllogism, whether the minor premiss be indefinite or particular: e.g. if all B is A and some C is not B, or 5if not all C is B. For the major term may be predicable both of all and of none of the minor, to some of which the middle term cannot be attributed. Suppose the terms are animal, man, white: next take some of the white things of which man is not predicated-swan and snow: animal is predicated of all of the one, but of none of the other. 10Consequently there cannot be a syllogism. Again let no B be A, but let some C not be B. Take the terms inanimate, man, white: then take some white things of which man is not predicated-swan and snow: the term inanimate is predicated of all of the one, of none of the other.
Further 15since it is indefinite to say some C is not B, and it is true that some C is not B, whether no C is B, or not all C is B, and since if terms are assumed such that no C is B, no syllogism follows (this has already been stated) it is clear that this arrangement of terms will not afford a syllogism: otherwise one would have been possible with a universal negative minor premiss. 20A similar proof may also be given if the universal premiss is negative.
Nor can there in any way be a syllogism if both the relations of subject and predicate are particular, either positively or negatively, or the one negative and the other affirmative, or one indefinite and the other definite, or both indefinite. 25Terms common to all the above are animal, white, horse: animal, white, stone.
It is clear then from what has been said that if there is a syllogism in this figure with a particular conclusion, the terms must be related as we have stated: if they are related otherwise, no syllogism is possible anyhow. It is evident also that all the syllogisms in this figure are perfect 30(for they are all completed by means of the premisses originally taken) and that all conclusions are proved by this figure, viz. universal and particular, affirmative and negative. Such a figure I call the first.
Book 1,Chapter 5 (26b34–28a9)
Ὅταν δὲ τὸ αὐτὸ τῷ μὲν παντὶ τῷ δὲ μηδενὶ ὑπάρχῃ,
35 ἢ ἑκατέρῳ παντὶ ἢ μηδενί, τὸ μὲν σχῆμα τὸ τοιοῦτον
καλῶ δεύτερον, μέσον δὲ ἐν αὐτῷ λέγω τὸ κατηγορούμενον
ἀμφοῖν, ἄκρα δὲ καθ' ὧν λέγεται τοῦτο, μεῖζον δὲ ἄκρον τὸ
πρὸς τῷ μέσῳ κείμενον· ἔλαττον δὲ τὸ πορρωτέρω τοῦ μέσου.
τίθεται δὲ τὸ μέσον ἔξω μὲν τῶν ἄκρων, πρῶτον δὲ τῇ θέσει.
34Whenever the same thing belongs to all of one subject, and to none of another, 35or to all of each subject or to none of either, I call such a figure the second; by middle term in it I mean that which is predicated of both subjects, by extremes the terms of which this is said, by major extreme that which lies near the middle, by minor that which is further away from the middle. The middle term stands outside the extremes, and is first in position.
27a
1 τέλειος μὲν οὖν οὐκ ἔσται συλλογισμὸς οὐδαμῶς ἐν τούτῳ τῷ σχήματι,
δυνατὸς δ' ἔσται καὶ καθόλου καὶ μὴ καθόλου τῶν ὅρων
ὄντων. καθόλου μὲν οὖν ὄντων ἔσται συλλογισμὸς ὅταν τὸ μέσον
τῷ μὲν παντὶ τῷ δὲ μηδενὶ ὑπάρχῃ, ἂν πρὸς ὁποτερῳοῦν
5 ᾖ τὸ στερητικόν· ἄλλως δ' οὐδαμῶς. κατηγορείσθω γὰρ τὸ Μ
τοῦ μὲν Ν μηδενός, τοῦ δὲ Ξ παντός. ἐπεὶ οὖν ἀντιστρέφει τὸ
στερητικόν, οὐδενὶ τῷ Μ ὑπάρξει τὸ Ν· τὸ δέ γε Μ παντὶ τῷ
Ξ ὑπέκειτο· ὥστε τὸ Ν οὐδενὶ τῷ Ξ· τοῦτο γὰρ δέδεικται πρότερον.
πάλιν εἰ τὸ Μ τῷ μὲν Ν παντὶ τῷ δὲ Ξ μηδενί,
10 οὐδὲ τὸ Ξ τῷ Ν οὐδενὶ ὑπάρξει (εἰ γὰρ τὸ Μ οὐδενὶ τῷ Ξ, οὐδὲ
τὸ Ξ οὐδενὶ τῷ Μ· τὸ δέ γε Μ παντὶ τῷ Ν ὑπῆρχεν· τὸ ἄρα
Ξ οὐδενὶ τῷ Ν ὑπάρξει· γεγένηται γὰρ πάλιν τὸ πρῶτον
σχῆμα)· ἐπεὶ δὲ ἀντιστρέφει τὸ στερητικόν, οὐδὲ τὸ Ν οὐδενὶ τῷ
Ξ ὑπάρξει, ὥστ' ἔσται ὁ αὐτὸς συλλογισμός. ἔστι δὲ δεικνύναι
15 ταῦτα καὶ εἰς τὸ ἀδύνατον ἄγοντας. ὅτι μὲν οὖν γίνεται συλλογισμὸς
οὕτως ἐχόντων τῶν ὅρων, φανερόν, ἀλλ' οὐ τέλειος· οὐ
γὰρ μόνον ἐκ τῶν ἐξ ἀρχῆς ἀλλὰ καὶ ἐξ ἄλλων ἐπιτελεῖται τὸ
ἀναγκαῖον. ἐὰν δὲ τὸ Μ παντὸς τοῦ Ν καὶ τοῦ Ξ κατηγορῆται,
οὐκ ἔσται συλλογισμός. ὅροι τοῦ ὑπάρχειν οὐσία—ζῷον—ἄνθρωπος,
20 τοῦ μὴ ὑπάρχειν οὐσία—ζῷον—ἀριθμός· μέσον οὐσία. οὐδ' ὅταν
μήτε τοῦ Ν μήτε τοῦ Ξ μηδενὸς κατηγορῆται τὸ Μ. ὅροι τοῦ
ὑπάρχειν γραμμή—ζῷον—ἄνθρωπος, τοῦ μὴ ὑπάρχειν γραμμή—
ζῷον—λίθος. φανερὸν οὖν ὅτι ἂν ᾖ συλλογισμὸς καθόλου τῶν
ὅρων ὄντων, ἀνάγκη τοὺς ὅρους ἔχειν ὡς ἐν ἀρχῇ εἴπομεν·
25 ἄλλως γὰρ ἐχόντων οὐ γίνεται τὸ ἀναγκαῖον.
Ἐὰν δὲ πρὸς τὸν ἕτερον ᾖ καθόλου τὸ μέσον, ὅταν μὲν
πρὸς τὸν μείζω γένηται καθόλου ἢ κατηγορικῶς ἢ στερητικῶς,
πρὸς δὲ τὸν ἐλάττω κατὰ μέρος καὶ ἀντικειμένως τῷ καθόλου
(λέγω δὲ τὸ ἀντικειμένως, εἰ μὲν τὸ καθόλου στερητικόν, τὸ
30 ἐν μέρει καταφατικόν· εἰ δὲ κατηγορικὸν τὸ καθόλου, τὸ ἐν
μέρει στερητικόν), ἀνάγκη γίνεσθαι συλλογισμὸν στερητικὸν
κατὰ μέρος. εἰ γὰρ τὸ Μ τῷ μὲν Ν μηδενὶ τῷ δὲ Ξ τινὶ
ὑπάρχει, ἀνάγκη τὸ Ν τινὶ τῷ Ξ μὴ ὑπάρχειν. ἐπεὶ γὰρ
ἀντιστρέφει τὸ στερητικόν, οὐδενὶ τῷ Μ ὑπάρξει τὸ Ν· τὸ δέ γε Μ
35 ὑπέκειτο τινὶ τῷ Ξ ὑπάρχειν· ὥστε τὸ Ν τινὶ τῷ Ξ οὐχ ὑπάρξει·
γίνεται γὰρ συλλογισμὸς διὰ τοῦ πρώτου σχήματος. πάλιν
εἰ τῷ μὲν Ν παντὶ τὸ Μ, τῷ δὲ Ξ τινὶ μὴ ὑπάρχει,
ἀνάγκη τὸ Ν τινὶ τῷ Ξ μὴ ὑπάρχειν· εἰ γὰρ παντὶ ὑπάρχει,
κατηγορεῖται δὲ καὶ τὸ Μ παντὸς τοῦ Ν, ἀνάγκη τὸ Μ
1A syllogism cannot be perfect anyhow in this figure, but it may be valid whether the terms are related universally or not.
If then the terms are related universally a syllogism will be possible, whenever the middle belongs to all of one subject and to none of another (it does not matter which has the negative relation), 5but in no other way. Let M be predicated of no N, but of all O. Since, then, the negative relation is convertible, N will belong to no M: but M was assumed to belong to all O: consequently N will belong to no O. This has already been proved. Again if M belongs to all N, but to no O, 10then N will belong to no O. For if M belongs to no O, O belongs to no M: but M (as was said) belongs to all N: O then will belong to no N: for the first figure has again been formed. But since the negative relation is convertible, N will belong to no O. Thus it will be the same syllogism that proves both conclusions.
It is possible to prove these results 15also by reductio ad impossibile.
It is clear then that a syllogism is formed when the terms are so related, but not a perfect syllogism; for necessity is not perfectly established merely from the original premisses; others also are needed.
But if M is predicated of every N and O, there cannot be a syllogism. Terms to illustrate a positive relation between the extremes are substance, animal, man; 20a negative relation, substance, animal, number-substance being the middle term.
Nor is a syllogism possible when M is predicated neither of any N nor of any O. Terms to illustrate a positive relation are line, animal, man: a negative relation, line, animal, stone.
It is clear then that if a syllogism is formed when the terms are universally related, the terms must be related as we stated at the outset: 25for if they are otherwise related no necessary consequence follows.
If the middle term is related universally to one of the extremes, a particular negative syllogism must result whenever the middle term is related universally to the major whether positively or negatively, and particularly to the minor and in a manner opposite to that of the universal statement: by 'an opposite manner' I mean, if the universal statement is negative, 30the particular is affirmative: if the universal is affirmative, the particular is negative. For if M belongs to no N, but to some O, it is necessary that N does not belong to some O. For since the negative statement is convertible, N will belong to no M: 35but M was admitted to belong to some O: therefore N will not belong to some O: for the result is reached by means of the first figure. Again if M belongs to all N, but not to some O, it is necessary that N does not belong to some O: for if N belongs to all O, and M is predicated also of all N, M must belong to all O: but we assumed that M does not belong to some O.
If then the terms are related universally a syllogism will be possible, whenever the middle belongs to all of one subject and to none of another (it does not matter which has the negative relation), 5but in no other way. Let M be predicated of no N, but of all O. Since, then, the negative relation is convertible, N will belong to no M: but M was assumed to belong to all O: consequently N will belong to no O. This has already been proved. Again if M belongs to all N, but to no O, 10then N will belong to no O. For if M belongs to no O, O belongs to no M: but M (as was said) belongs to all N: O then will belong to no N: for the first figure has again been formed. But since the negative relation is convertible, N will belong to no O. Thus it will be the same syllogism that proves both conclusions.
It is possible to prove these results 15also by reductio ad impossibile.
It is clear then that a syllogism is formed when the terms are so related, but not a perfect syllogism; for necessity is not perfectly established merely from the original premisses; others also are needed.
But if M is predicated of every N and O, there cannot be a syllogism. Terms to illustrate a positive relation between the extremes are substance, animal, man; 20a negative relation, substance, animal, number-substance being the middle term.
Nor is a syllogism possible when M is predicated neither of any N nor of any O. Terms to illustrate a positive relation are line, animal, man: a negative relation, line, animal, stone.
It is clear then that if a syllogism is formed when the terms are universally related, the terms must be related as we stated at the outset: 25for if they are otherwise related no necessary consequence follows.
If the middle term is related universally to one of the extremes, a particular negative syllogism must result whenever the middle term is related universally to the major whether positively or negatively, and particularly to the minor and in a manner opposite to that of the universal statement: by 'an opposite manner' I mean, if the universal statement is negative, 30the particular is affirmative: if the universal is affirmative, the particular is negative. For if M belongs to no N, but to some O, it is necessary that N does not belong to some O. For since the negative statement is convertible, N will belong to no M: 35but M was admitted to belong to some O: therefore N will not belong to some O: for the result is reached by means of the first figure. Again if M belongs to all N, but not to some O, it is necessary that N does not belong to some O: for if N belongs to all O, and M is predicated also of all N, M must belong to all O: but we assumed that M does not belong to some O.
27b
1 παντὶ τῷ Ξ ὑπάρχειν· ὑπέκειτο δὲ τινὶ μὴ ὑπάρχειν. καὶ εἰ
τὸ Μ τῷ μὲν Ν παντὶ ὑπάρχει τῷ δὲ Ξ μὴ παντί, ἔσται
συλλογισμὸς ὅτι οὐ παντὶ τῷ Ξ τὸ Ν· ἀπόδειξις δ' ἡ αὐτή.
ἐὰν δὲ τοῦ μὲν Ξ παντὸς τοῦ δὲ Ν μὴ παντὸς κατηγορῆται,
5 οὐκ ἔσται συλλογισμός. ὅροι ζῷον—οὐσία—κόραξ, ζῷον—λευκόν—
κόραξ. οὐδ' ὅταν τοῦ μὲν Ξ μηδενός, τοῦ δὲ Ν τινός. ὅροι τοῦ
ὑπάρχειν ζῷον—οὐσία—μονάς, τοῦ μὴ ὑπάρχειν ζῷον—οὐσία—
ἐπιστήμη.
Ὅταν μὲν οὖν ἀντικείμενον ᾖ τὸ καθόλου τῷ κατὰ μέρος,
10 εἴρηται πότ' ἔσται καὶ πότ' οὐκ ἔσται συλλογισμός· ὅταν δὲ
ὁμοιοσχήμονες ὦσιν αἱ προτάσεις, οἷον ἀμφότεραι στερητικαὶ
ἢ καταφατικαί, οὐδαμῶς ἔσται συλλογισμός. ἔστωσαν γὰρ
πρῶτον στερητικαί, καὶ τὸ καθόλου κείσθω πρὸς τὸ μεῖζον
ἄκρον, οἷον τὸ Μ τῷ μὲν Ν μηδενὶ τῷ δὲ Ξ τινὶ μὴ ὑπαρχέτω·
15 ἐνδέχεται δὴ καὶ παντὶ καὶ μηδενὶ τῷ Ξ τὸ Ν ὑπάρχειν.
ὅροι τοῦ μὲν μὴ ὑπάρχειν μέλαν—χιών—ζῷον· τοῦ δὲ παντὶ
ὑπάρχειν οὐκ ἔστι λαβεῖν, εἰ τὸ Μ τῷ Ξ τινὶ μὲν ὑπάρχει
τινὶ δὲ μή. εἰ γὰρ παντὶ τῷ Ξ τὸ Ν, τὸ δὲ Μ μηδενὶ τῷ Ν,
τὸ Μ οὐδενὶ τῷ Ξ ὑπάρξει· ἀλλ' ὑπέκειτο τινὶ ὑπάρχειν.
20 οὕτω μὲν οὖν οὐκ ἐγχωρεῖ λαβεῖν ὅρους, ἐκ δὲ τοῦ ἀδιορίστου δεικτέον·
ἐπεὶ γὰρ ἀληθεύεται τὸ τινὶ μὴ ὑπάρχειν τὸ Μ τῷ
Ξ καὶ εἰ μηδενὶ ὑπάρχει, μηδενὶ δὲ ὑπάρχοντος οὐκ ἦν συλλογισμός,
φανερὸν ὅτι οὐδὲ νῦν ἔσται. πάλιν ἔστωσαν κατηγορικαί,
καὶ τὸ καθόλου κείσθω ὁμοίως, οἷον τὸ Μ τῷ μὲν Ν
25 παντὶ τῷ δὲ Ξ τινὶ ὑπαρχέτω. ἐνδέχεται δὴ τὸ Ν τῷ Ξ καὶ
παντὶ καὶ μηδενὶ ὑπάρχειν. ὅροι τοῦ μηδενὶ ὑπάρχειν λευκόν—
κύκνος—λίθος τοῦ δὲ παντὶ οὐκ ἔσται λαβεῖν διὰ τὴν αὐτὴν αἰτίαν
ἥνπερ πρότερον, ἀλλ' ἐκ τοῦ ἀδιορίστου δεικτέον. εἰ δὲ τὸ
καθόλου πρὸς τὸ ἔλαττον ἄκρον ἐστί, καὶ τὸ Μ τῷ μὲν Ξ μηδενὶ
30 τῷ δὲ Ν τινὶ μὴ ὑπάρχει, ἐνδέχεται τὸ Ν τῷ Ξ καὶ
παντὶ καὶ μηδενὶ ὑπάρχειν. ὅροι τοῦ ὑπάρχειν λευκόν—ζῷον—
κόραξ, τοῦ μὴ ὑπάρχειν λευκόν—λίθος—κόραξ. εἰ δὲ κατηγορικαὶ
αἱ προτάσεις, ὅροι τοῦ μὴ ὑπάρχειν λευκόν—ζῷον—χιών,
τοῦ ὑπάρχειν λευκόν—ζῷον—κύκνος. φανερὸν οὖν, ὅταν ὁμοιοσχήμονες
35 ὦσιν αἱ προτάσεις καὶ ἡ μὲν καθόλου ἡ δ' ἐν μέρει, ὅτι
οὐδαμῶς γίνεται συλλογισμός. ἀλλ' οὐδ' εἰ τινὶ ἑκατέρῳ ὑπάρχει
ἢ μὴ ὑπάρχει, ἢ τῷ μὲν τῷ δὲ μή, ἢ μηδετέρῳ παντί,
ἢ ἀδιορίστως. ὅροι δὲ κοινοὶ πάντων λευκόν—ζῷον—ἄνθρωπος,
λευκόν—ζῷον—ἄψυχον.
1And if M belongs to all N but not to all O, we shall conclude that N does not belong to all O: the proof is the same as the above. But if M is predicated of all O, but not of all N, 5there will be no syllogism. Take the terms animal, substance, raven; animal, white, raven. Nor will there be a conclusion when M is predicated of no O, but of some N. Terms to illustrate a positive relation between the extremes are animal, substance, unit: a negative relation, animal, substance, science.
If then the universal statement is opposed to the particular, 10we have stated when a syllogism will be possible and when not: but if the premisses are similar in form, I mean both negative or both affirmative, a syllogism will not be possible anyhow. First let them be negative, and let the major premiss be universal, e.g. let M belong to no N, and not to some O. 15It is possible then for N to belong either to all O or to no O. Terms to illustrate the negative relation are black, snow, animal. But it is not possible to find terms of which the extremes are related positively and universally, if M belongs to some O, and does not belong to some O. For if N belonged to all O, but M to no N, then M would belong to no O: but we assumed that it belongs to some O. 20In this way then it is not admissible to take terms: our point must be proved from the indefinite nature of the particular statement. For since it is true that M does not belong to some O, even if it belongs to no O, and since if it belongs to no O a syllogism is (as we have seen) not possible, clearly it will not be possible now either.
Again let the premisses be affirmative, and let the major premiss as before be universal, e.g. 25let M belong to all N and to some O. It is possible then for N to belong to all O or to no O. Terms to illustrate the negative relation are white, swan, stone. But it is not possible to take terms to illustrate the universal affirmative relation, for the reason already stated: the point must be proved from the indefinite nature of the particular statement. But if the minor premiss is universal, 30and M belongs to no O, and not to some N, it is possible for N to belong either to all O or to no O. Terms for the positive relation are white, animal, raven: for the negative relation, white, stone, raven. If the premisses are affirmative, terms for the negative relation are white, animal, snow; for the positive relation, white, animal, swan. Evidently then, 35whenever the premisses are similar in form, and one is universal, the other particular, a syllogism can, not be formed anyhow. Nor is one possible if the middle term belongs to some of each of the extremes, or does not belong to some of either, or belongs to some of the one, not to some of the other, or belongs to neither universally, or is related to them indefinitely.
If then the universal statement is opposed to the particular, 10we have stated when a syllogism will be possible and when not: but if the premisses are similar in form, I mean both negative or both affirmative, a syllogism will not be possible anyhow. First let them be negative, and let the major premiss be universal, e.g. let M belong to no N, and not to some O. 15It is possible then for N to belong either to all O or to no O. Terms to illustrate the negative relation are black, snow, animal. But it is not possible to find terms of which the extremes are related positively and universally, if M belongs to some O, and does not belong to some O. For if N belonged to all O, but M to no N, then M would belong to no O: but we assumed that it belongs to some O. 20In this way then it is not admissible to take terms: our point must be proved from the indefinite nature of the particular statement. For since it is true that M does not belong to some O, even if it belongs to no O, and since if it belongs to no O a syllogism is (as we have seen) not possible, clearly it will not be possible now either.
Again let the premisses be affirmative, and let the major premiss as before be universal, e.g. 25let M belong to all N and to some O. It is possible then for N to belong to all O or to no O. Terms to illustrate the negative relation are white, swan, stone. But it is not possible to take terms to illustrate the universal affirmative relation, for the reason already stated: the point must be proved from the indefinite nature of the particular statement. But if the minor premiss is universal, 30and M belongs to no O, and not to some N, it is possible for N to belong either to all O or to no O. Terms for the positive relation are white, animal, raven: for the negative relation, white, stone, raven. If the premisses are affirmative, terms for the negative relation are white, animal, snow; for the positive relation, white, animal, swan. Evidently then, 35whenever the premisses are similar in form, and one is universal, the other particular, a syllogism can, not be formed anyhow. Nor is one possible if the middle term belongs to some of each of the extremes, or does not belong to some of either, or belongs to some of the one, not to some of the other, or belongs to neither universally, or is related to them indefinitely.
28a
1 Φανερὸν οὖν ἐκ τῶν εἰρημένων ὅτι ἐάν τε οὕτως ἔχωσιν οἱ
ὅροι πρὸς ἀλλήλους ὡς ἐλέχθη, γίνεται συλλογισμὸς ἐξ
ἀνάγκης, ἄν τ' ᾖ συλλογισμός, ἀνάγκη τοὺς ὅρους οὕτως ἔχειν.
δῆλον δὲ καὶ ὅτι πάντες ἀτελεῖς εἰσὶν οἱ ἐν τούτῳ τῷ σχήματι
5 συλλογισμοί (πάντες γὰρ ἐπιτελοῦνται προσλαμβανομένων
τινῶν, ἃ ἢ ἐνυπάρχει τοῖς ὅροις ἐξ ἀνάγκης ἢ τίθενται ὡς
ὑποθέσεις, οἷον ὅταν διὰ τοῦ ἀδυνάτου δεικνύωμεν), καὶ ὅτι οὐ
γίνεται καταφατικὸς συλλογισμὸς διὰ τούτου τοῦ σχήματος,
ἀλλὰ πάντες στερητικοί, καὶ οἱ καθόλου καὶ οἱ κατὰ μέρος.
1Common terms for all the above are white, animal, man: white, animal, inanimate. It is clear then from what has been said that if the terms are related to one another in the way stated, a syllogism results of necessity; and if there is a syllogism, the terms must be so related. But it is evident also that all the syllogisms in this figure 5are imperfect: for all are made perfect by certain supplementary statements, which either are contained in the terms of necessity or are assumed as hypotheses, i.e. when we prove per impossibile. And it is evident that an affirmative conclusion is not attained by means of this figure, but all are negative, whether universal or particular.
Book 1,Chapter 6 (28a10–29a18)
10 Ἐὰν δὲ τῷ αὐτῷ τὸ μὲν παντὶ τὸ δὲ μηδενὶ ὑπάρχῃ,
ἢ ἄμφω παντὶ ἢ μηδενί, τὸ μὲν σχῆμα τὸ τοιοῦτον καλῶ
τρίτον, μέσον δ' ἐν αὐτῷ λέγω καθ' οὗ ἄμφω τὰ κατηγορούμενα,
ἄκρα δὲ τὰ κατηγορούμενα, μεῖζον δ' ἄκρον τὸ πορρώτερον
τοῦ μέσου, ἔλαττον δὲ τὸ ἐγγύτερον. τίθεται δὲ τὸ μέσον
15 ἔξω μὲν τῶν ἄκρων, ἔσχατον δὲ τῇ θέσει. τέλειος μὲν οὖν οὐ γίνεται
συλλογισμὸς οὐδ' ἐν τούτῳ τῷ σχήματι, δυνατὸς δ' ἔσται
καὶ καθόλου καὶ μὴ καθόλου τῶν ὅρων ὄντων πρὸς τὸ μέσον. Καθόλου
μὲν οὖν ὄντων, ὅταν καὶ τὸ Π καὶ τὸ Ρ παντὶ τῷ Σ ὑπάρχῃ, ὅτι
τινὶ τῷ Ρ τὸ Π ὑπάρξει ἐξ ἀνάγκης· ἐπεὶ γὰρ ἀντιστρέφει
20 τὸ κατηγορικόν, ὑπάρξει τὸ Σ τινὶ τῷ Ρ, ὥστ' ἐπεὶ τῷ μὲν Σ
παντὶ τὸ Π, τῷ δὲ Ρ τινὶ τὸ Σ, ἀνάγκη τὸ Π τινὶ τῷ Ρ ὑπάρχειν·
γίνεται γὰρ συλλογισμὸς διὰ τοῦ πρώτου σχήματος. ἔστι
δὲ καὶ διὰ τοῦ ἀδυνάτου καὶ τῷ ἐκθέσθαι ποιεῖν τὴν ἀπόδειξιν·
εἰ γὰρ ἄμφω παντὶ τῷ Σ ὑπάρχει, ἂν ληφθῇ τι τῶν Σ οἷον
25 τὸ Ν, τούτῳ καὶ τὸ Π καὶ τὸ Ρ ὑπάρξει, ὥστε τινὶ τῷ Ρ τὸ Π
ὑπάρξει. καὶ ἂν τὸ μὲν Ρ παντὶ τῷ Σ, τὸ δὲ Π μηδενὶ
ὑπάρχῃ, ἔσται συλλογισμὸς ὅτι τὸ Π τινὶ τῷ Ρ οὐχ ὑπάρξει
ἐξ ἀνάγκης· ὁ γὰρ αὐτὸς τρόπος τῆς ἀποδείξεως ἀντιστραφείσης
τῆς Ρ Σ προτάσεως. δειχθείη δ' ἂν καὶ διὰ τοῦ
30 ἀδυνάτου, καθάπερ ἐπὶ τῶν πρότερον. ἐὰν δὲ τὸ μὲν Ρ μηδενὶ
τὸ δὲ Π παντὶ ὑπάρχῃ τῷ Σ, οὐκ ἔσται συλλογισμός. ὅροι
τοῦ ὑπάρχειν ζῷον—ἵππος—ἄνθρωπος, τοῦ μὴ ὑπάρχειν ζῷον—
ἄψυχον—ἄνθρωπος. οὐδ' ὅταν ἄμφω κατὰ μηδενὸς τοῦ Σ λέγηται,
οὐκ ἔσται συλλογισμός. ὅροι τοῦ ὑπάρχειν ζῷον—ἵππος—
35 ἄψυχον, τοῦ μὴ ὑπάρχειν ἄνθρωπος—ἵππος—ἄψυχον· μέσον
ἄψυχον. φανερὸν οὖν καὶ ἐν τούτῳ τῷ σχήματι πότ' ἔσται καὶ
πότ' οὐκ ἔσται συλλογισμὸς καθόλου τῶν ὅρων ὄντων. ὅταν μὲν
γὰρ ἀμφότεροι οἱ ὅροι ὦσι κατηγορικοί, ἔσται συλλογισμὸς
ὅτι τινὶ ὑπάρχει τὸ ἄκρον τῷ ἄκρῳ, ὅταν δὲ στερητικοί, οὐκ
10But if one term belongs to all, and another to none, of a third, or if both belong to all, or to none, of it, I call such a figure the third; by middle term in it I mean that of which both the predicates are predicated, by extremes I mean the predicates, by the major extreme that which is further from the middle, by the minor that which is nearer to it. The middle term stands 15outside the extremes, and is last in position. A syllogism cannot be perfect in this figure either, but it may be valid whether the terms are related universally or not to the middle term.
If they are universal, whenever both P and R belong to S, it follows that P will necessarily belong to some R. For, since the affirmative statement is convertible, 20S will belong to some R: consequently since P belongs to all S, and S to some R, P must belong to some R: for a syllogism in the first figure is produced. It is possible to demonstrate this also per impossibile and by exposition. For if both P and R belong to all S, should one of the Ss, e.g. 25N, be taken, both P and R will belong to this, and thus P will belong to some R.
If R belongs to all S, and P to no S, there will be a syllogism to prove that P will necessarily not belong to some R. This may be demonstrated in the same way as before by converting the premiss RS. It might be proved also per impossibile, 30as in the former cases. But if R belongs to no S, P to all S, there will be no syllogism. Terms for the positive relation are animal, horse, man: for the negative relation animal, inanimate, man.
Nor can there be a syllogism when both terms are asserted of no S. Terms for the positive relation are animal, horse, 35inanimate; for the negative relation man, horse, inanimate-inanimate being the middle term.
It is clear then in this figure also when a syllogism will be possible and when not, if the terms are related universally. For whenever both the terms are affirmative, there will be a syllogism to prove that one extreme belongs to some of the other; but when they are negative, no syllogism will be possible.
If they are universal, whenever both P and R belong to S, it follows that P will necessarily belong to some R. For, since the affirmative statement is convertible, 20S will belong to some R: consequently since P belongs to all S, and S to some R, P must belong to some R: for a syllogism in the first figure is produced. It is possible to demonstrate this also per impossibile and by exposition. For if both P and R belong to all S, should one of the Ss, e.g. 25N, be taken, both P and R will belong to this, and thus P will belong to some R.
If R belongs to all S, and P to no S, there will be a syllogism to prove that P will necessarily not belong to some R. This may be demonstrated in the same way as before by converting the premiss RS. It might be proved also per impossibile, 30as in the former cases. But if R belongs to no S, P to all S, there will be no syllogism. Terms for the positive relation are animal, horse, man: for the negative relation animal, inanimate, man.
Nor can there be a syllogism when both terms are asserted of no S. Terms for the positive relation are animal, horse, 35inanimate; for the negative relation man, horse, inanimate-inanimate being the middle term.
It is clear then in this figure also when a syllogism will be possible and when not, if the terms are related universally. For whenever both the terms are affirmative, there will be a syllogism to prove that one extreme belongs to some of the other; but when they are negative, no syllogism will be possible.
28b
1 ἔσται. ὅταν δ' ὁ μὲν ᾖ στερητικὸς ὁ δὲ καταφατικός, ἐὰν μὲν
ὁ μείζων γένηται στερητικὸς ἅτερος δὲ καταφατικός, ἔσται
συλλογισμὸς ὅτι τινὶ οὐχ ὑπάρχει τὸ ἄκρον τῷ ἄκρῳ, ἐὰν
δ' ἀνάπαλιν, οὐκ ἔσται.
5 Ἐὰν δ' ὁ μὲν ᾖ καθόλου πρὸς τὸ μέσον ὁ δ' ἐν μέρει,
κατηγορικῶν μὲν ὄντων ἀμφοῖν ἀνάγκη γίνεσθαι συλλογισμόν,
ἂν ὁποτεροσοῦν ᾖ καθόλου τῶν ὅρων. εἰ γὰρ τὸ μὲν Ρ
παντὶ τῷ Σ τὸ δὲ Π τινί, ἀνάγκη τὸ Π τινὶ τῷ Ρ ὑπάρχειν.
ἐπεὶ γὰρ ἀντιστρέφει τὸ καταφατικόν, ὑπάρξει τὸ Σ
10 τινὶ τῷ Π, ὥστ' ἐπεὶ τὸ μὲν Ρ παντὶ τῷ Σ, τὸ δὲ Σ τινὶ τῷ
Π, καὶ τὸ Ρ τινὶ τῷ Π ὑπάρξει· ὥστε τὸ Π τινὶ τῷ Ρ. πάλιν
εἰ τὸ μὲν Ρ τινὶ τῷ Σ τὸ δὲ Π παντὶ ὑπάρχει, ἀνάγκη
τὸ Π τινὶ τῷ Ρ ὑπάρχειν· ὁ γὰρ αὐτὸς τρόπος τῆς ἀποδείξεως.
ἔστι δ' ἀποδεῖξαι καὶ διὰ τοῦ ἀδυνάτου καὶ τῇ ἐκθέσει,
15 καθάπερ ἐπὶ τῶν πρότερον. Ἐὰν δ' ὁ μὲν ᾖ κατηγορικὸς ὁ δὲ
στερητικός, καθόλου δὲ ὁ κατηγορικός, ὅταν μὲν ὁ ἐλάττων ᾖ
κατηγορικός, ἔσται συλλογισμός. εἰ γὰρ τὸ Ρ παντὶ τῷ Σ,
τὸ δὲ Π τινὶ μὴ ὑπάρχει, ἀνάγκη τὸ Π τινὶ τῷ Ρ μὴ ὑπάρχειν.
εἰ γὰρ παντί, καὶ τὸ Ρ παντὶ τῷ Σ, καὶ τὸ Π παντὶ
20 τῷ Σ ὑπάρξει· ἀλλ' οὐχ ὑπῆρχεν. δείκνυται δὲ καὶ ἄνευ τῆς
ἀπαγωγῆς, ἐὰν ληφθῇ τι τῶν Σ ᾧ τὸ Π μὴ ὑπάρχει.
ὅταν δ' ὁ μείζων ᾖ κατηγορικός, οὐκ ἔσται συλλογισμός, οἷον
εἰ τὸ μὲν Π παντὶ τῷ Σ, τὸ δὲ Ρ τινὶ τῷ Σ μὴ ὑπάρχει. ὅροι
τοῦ παντὶ ὑπάρχειν ἔμψυχον—ἄνθρωπος—ζῷον. τοῦ δὲ μηδενὶ
25 οὐκ ἔστι λαβεῖν ὅρους, εἰ τινὶ μὲν ὑπάρχει τῷ Σ τὸ Ρ, τινὶ δὲ
μή· εἰ γὰρ παντὶ τὸ Π τῷ Σ ὑπάρχει, τὸ δὲ Ρ τινὶ τῷ Σ,
καὶ τὸ Π τινὶ τῷ Ρ ὑπάρξει· ὑπέκειτο δὲ μηδενὶ ὑπάρχειν.
ἀλλ' ὥσπερ ἐν τοῖς πρότερον ληπτέον· ἀδιορίστου γὰρ ὄντος τοῦ
τινὶ μὴ ὑπάρχειν καὶ τὸ μηδενὶ ὑπάρχον ἀληθὲς εἰπεῖν τινὶ μὴ
30 ὑπάρχειν· μηδενὶ δὲ ὑπάρχοντος οὐκ ἦν συλλογισμός. φανερὸν
οὖν ὅτι οὐκ ἔσται συλλογισμός. ἐὰν δ' ὁ στερητικὸς ᾖ καθόλου τῶν
ὅρων, ὅταν μὲν ὁ μείζων ᾖ στερητικὸς ὁ δὲ ἐλάττων κατηγορικός,
ἔσται συλλογισμός. εἰ γὰρ τὸ Π μηδενὶ τῷ Σ, τὸ δὲ Ρ
τινὶ ὑπάρχει τῷ Σ, τὸ Π τινὶ τῷ Ρ οὐχ ὑπάρξει· πάλιν γὰρ
35 ἔσται τὸ πρῶτον σχῆμα τῆς Ρ Σ προτάσεως ἀντιστραφείσης.
ὅταν δὲ ὁ ἐλάττων ᾖ στερητικός, οὐκ ἔσται συλλογισμός. ὅροι
τοῦ ὑπάρχειν ζῷον—ἄνθρωπος—ἄγριον, τοῦ μὴ ὑπάρχειν ζῷον—
ἐπιστήμη—ἄγριον· μέσον ἐν ἀμφοῖν τὸ ἄγριον. οὐδ' ὅταν ἀμφότεροι
στερητικοὶ τεθῶσιν, ᾖ δ' ὁ μὲν καθόλου ὁ δ' ἐν μέρει. ὅροι
1But when one is negative, the other affirmative, if the major is negative, the minor affirmative, there will be a syllogism to prove that the one extreme does not belong to some of the other: but if the relation is reversed, no syllogism will be possible. 5If one term is related universally to the middle, the other in part only, when both are affirmative there must be a syllogism, no matter which of the premisses is universal. For if R belongs to all S, P to some S, P must belong to some R. For since the affirmative statement is convertible S will belong 10to some P: consequently since R belongs to all S, and S to some P, R must also belong to some P: therefore P must belong to some R.
Again if R belongs to some S, and P to all S, P must belong to some R. This may be demonstrated in the same way as the preceding. And it is possible to demonstrate it also per impossibile and by exposition, 15as in the former cases. But if one term is affirmative, the other negative, and if the affirmative is universal, a syllogism will be possible whenever the minor term is affirmative. For if R belongs to all S, but P does not belong to some S, it is necessary that P does not belong to some R. For if P belongs to all R, and R belongs to all S, then P will belong to all 20S: but we assumed that it did not. Proof is possible also without reduction ad impossibile, if one of the Ss be taken to which P does not belong.
But whenever the major is affirmative, no syllogism will be possible, e.g. if P belongs to all S and R does not belong to some S. Terms for the universal affirmative relation are animate, man, animal. For the universal negative relation 25it is not possible to get terms, if R belongs to some S, and does not belong to some S. For if P belongs to all S, and R to some S, then P will belong to some R: but we assumed that it belongs to no R. We must put the matter as before.' Since the expression 'it does not belong to some' is indefinite, it may be used truly of that also which belongs to none. 30But if R belongs to no S, no syllogism is possible, as has been shown. Clearly then no syllogism will be possible here.
But if the negative term is universal, whenever the major is negative and the minor affirmative there will be a syllogism. For if P belongs to no S, and R belongs to some S, P will not belong to some R: 35for we shall have the first figure again, if the premiss RS is converted.
But when the minor is negative, there will be no syllogism. Terms for the positive relation are animal, man, wild: for the negative relation, animal, science, wild-the middle in both being the term wild.
Nor is a syllogism possible when both are stated in the negative, but one is universal, the other particular. When the minor is related universally to the middle, take the terms animal, science, wild; animal, man, wild.
Again if R belongs to some S, and P to all S, P must belong to some R. This may be demonstrated in the same way as the preceding. And it is possible to demonstrate it also per impossibile and by exposition, 15as in the former cases. But if one term is affirmative, the other negative, and if the affirmative is universal, a syllogism will be possible whenever the minor term is affirmative. For if R belongs to all S, but P does not belong to some S, it is necessary that P does not belong to some R. For if P belongs to all R, and R belongs to all S, then P will belong to all 20S: but we assumed that it did not. Proof is possible also without reduction ad impossibile, if one of the Ss be taken to which P does not belong.
But whenever the major is affirmative, no syllogism will be possible, e.g. if P belongs to all S and R does not belong to some S. Terms for the universal affirmative relation are animate, man, animal. For the universal negative relation 25it is not possible to get terms, if R belongs to some S, and does not belong to some S. For if P belongs to all S, and R to some S, then P will belong to some R: but we assumed that it belongs to no R. We must put the matter as before.' Since the expression 'it does not belong to some' is indefinite, it may be used truly of that also which belongs to none. 30But if R belongs to no S, no syllogism is possible, as has been shown. Clearly then no syllogism will be possible here.
But if the negative term is universal, whenever the major is negative and the minor affirmative there will be a syllogism. For if P belongs to no S, and R belongs to some S, P will not belong to some R: 35for we shall have the first figure again, if the premiss RS is converted.
But when the minor is negative, there will be no syllogism. Terms for the positive relation are animal, man, wild: for the negative relation, animal, science, wild-the middle in both being the term wild.
Nor is a syllogism possible when both are stated in the negative, but one is universal, the other particular. When the minor is related universally to the middle, take the terms animal, science, wild; animal, man, wild.
29a
1 ὅταν ὁ ἐλάττων ᾖ καθόλου πρὸς τὸ μέσον, ζῷον—ἐπιστήμη—
ἄγριον, ζῷον—ἄνθρωπος—ἄγριον· ὅταν δ' ὁ μείζων, τοῦ μὲν
μὴ ὑπάρχειν κόραξ—χιών—λευκόν. τοῦ δ' ὑπάρχειν οὐκ ἔστι
λαβεῖν, εἰ τὸ Ρ τινὶ μὲν ὑπάρχει τῷ Σ, τινὶ δὲ μὴ ὑπάρχει.
5 εἰ γὰρ τὸ Π παντὶ τῷ Ρ, τὸ δὲ Ρ τινὶ τῷ Σ, καὶ τὸ Π τινὶ τῷ
Σ· ὑπέκειτο δὲ μηδενί. ἀλλ' ἐκ τοῦ ἀδιορίστου δεικτέον. Οὐδ' ἂν
ἑκάτερος τινὶ τῷ μέσῳ ὑπάρχῃ ἢ μὴ ὑπάρχῃ, ἢ ὁ μὲν ὑπάρχῃ
ὁ δὲ μὴ ὑπάρχῃ, ἢ ὁ μὲν τινὶ ὁ δὲ μὴ παντί, ἢ ἀδιορίστως,
οὐκ ἔσται συλλογισμὸς οὐδαμῶς. ὅροι δὲ κοινοὶ πάντων ζῷον—
10 ἄνθρωπος—λευκόν, ζῷον—ἄψυχον—λευκόν.
Φανερὸν οὖν καὶ ἐν τούτῳ τῷ σχήματι πότ' ἔσται καὶ πότ'
οὐκ ἔσται συλλογισμός, καὶ ὅτι ἐχόντων τε τῶν ὅρων ὡς
ἐλέχθη γίνεται συλλογισμὸς ἐξ ἀνάγκης, ἄν τ' ᾖ συλλογισμός,
ἀνάγκη τοὺς ὅρους οὕτως ἔχειν. φανερὸν δὲ καὶ ὅτι πάντες
15 ἀτελεῖς εἰσὶν οἱ ἐν τούτῳ τῷ σχήματι συλλογισμοί (πάντες
γὰρ τελειοῦνται προσλαμβανομένων τινῶν) καὶ ὅτι συλλογίσασθαι
τὸ καθόλου διὰ τούτου τοῦ σχήματος οὐκ ἔσται, οὔτε
στερητικὸν οὔτε καταφατικόν.
1When the major is related universally to the middle, take as terms for a negative relation raven, snow, white. For a positive relation terms cannot be found, if R belongs to some S, and does not belong to some S. 5For if P belongs to all R, and R to some S, then P belongs to some S: but we assumed that it belongs to no S. Our point, then, must be proved from the indefinite nature of the particular statement.
Nor is a syllogism possible anyhow, if each of the extremes belongs to some of the middle or does not belong, or one belongs and the other does not to some of the middle, or one belongs to some of the middle, the other not to all, or if the premisses are indefinite. Common terms for all are animal, 10man, white: animal, inanimate, white.
It is clear then in this figure also when a syllogism will be possible, and when not; and that if the terms are as stated, a syllogism results of necessity, and if there is a syllogism, the terms must be so related. It is clear also that all 15the syllogisms in this figure are imperfect (for all are made perfect by certain supplementary assumptions), and that it will not be possible to reach a universal conclusion by means of this figure, whether negative or affirmative.
Nor is a syllogism possible anyhow, if each of the extremes belongs to some of the middle or does not belong, or one belongs and the other does not to some of the middle, or one belongs to some of the middle, the other not to all, or if the premisses are indefinite. Common terms for all are animal, 10man, white: animal, inanimate, white.
It is clear then in this figure also when a syllogism will be possible, and when not; and that if the terms are as stated, a syllogism results of necessity, and if there is a syllogism, the terms must be so related. It is clear also that all 15the syllogisms in this figure are imperfect (for all are made perfect by certain supplementary assumptions), and that it will not be possible to reach a universal conclusion by means of this figure, whether negative or affirmative.
Book 1,Chapter 7 (29a19–29b28)
Δῆλον δὲ καὶ ὅτι ἐν ἅπασι τοῖς σχήμασιν, ὅταν μὴ γίνηται
20 συλλογισμός, κατηγορικῶν μὲν ἢ στερητικῶν ἀμφοτέρων
ὄντων τῶν ὅρων οὐδὲν ὅλως γίνεται ἀναγκαῖον, κατηγορικοῦ
δὲ καὶ στερητικοῦ, καθόλου ληφθέντος τοῦ στερητικοῦ ἀεὶ γίνεται
συλλογισμὸς τοῦ ἐλάττονος ἄκρου πρὸς τὸ μεῖζον, οἷον εἰ τὸ
μὲν Α παντὶ τῷ Β ἢ τινί, τὸ δὲ Β μηδενὶ τῷ Γ· ἀντιστρεφομένων
25 γὰρ τῶν προτάσεων ἀνάγκη τὸ Γ τινὶ τῷ Α μὴ ὑπάρχειν.
ὁμοίως δὲ κἀπὶ τῶν ἑτέρων σχημάτων· ἀεὶ γὰρ γίνεται
διὰ τῆς ἀντιστροφῆς συλλογισμός. δῆλον δὲ καὶ ὅτι τὸ ἀδιόριστον
ἀντὶ τοῦ κατηγορικοῦ τοῦ ἐν μέρει τιθέμενον τὸν αὐτὸν
ποιήσει συλλογισμὸν ἐν ἅπασι τοῖς σχήμασιν.
30 Φανερὸν δὲ καὶ ὅτι πάντες οἱ ἀτελεῖς συλλογισμοὶ τελειοῦνται
διὰ τοῦ πρώτου σχήματος. ἢ γὰρ δεικτικῶς ἢ διὰ τοῦ
ἀδυνάτου περαίνονται πάντες· ἀμφοτέρως δὲ γίνεται τὸ πρῶτον
σχῆμα, δεικτικῶς μὲν τελειουμένων, ὅτι διὰ τῆς ἀντιστροφῆς
ἐπεραίνοντο πάντες, ἡ δ' ἀντιστροφὴ τὸ πρῶτον ἐποίει σχῆμα,
35 διὰ δὲ τοῦ ἀδυνάτου δεικνυμένων, ὅτι τεθέντος τοῦ ψεύδους ὁ συλλογισμὸς
γίνεται διὰ τοῦ πρώτου σχήματος, οἷον ἐν τῷ τελευταίῳ
σχήματι, εἰ τὸ Α καὶ τὸ Β παντὶ τῷ Γ ὑπάρχει, ὅτι τὸ
Α τινὶ τῷ Β ὑπάρχει· εἰ γὰρ μηδενί, τὸ δὲ Β παντὶ τῷ Γ,
οὐδενὶ τῷ Γ τὸ Α· ἀλλ' ἦν παντί. ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.
19It is evident also that in all the figures, whenever a proper syllogism does not result, 20if both the terms are affirmative or negative nothing necessary follows at all, but if one is affirmative, the other negative, and if the negative is stated universally, a syllogism always results relating the minor to the major term, e.g. if A belongs to all or some B, and B belongs to no C: for if the premisses are converted 25it is necessary that C does not belong to some A. Similarly also in the other figures: a syllogism always results by means of conversion. It is evident also that the substitution of an indefinite for a particular affirmative will effect the same syllogism in all the figures.
30It is clear too that all the imperfect syllogisms are made perfect by means of the first figure. For all are brought to a conclusion either ostensively or per impossibile. In both ways the first figure is formed: if they are made perfect ostensively, because (as we saw) all are brought to a conclusion by means of conversion, and conversion produces the first figure: 35if they are proved per impossibile, because on the assumption of the false statement the syllogism comes about by means of the first figure, e.g. in the last figure, if A and B belong to all C, it follows that A belongs to some B: for if A belonged to no B, and B belongs to all C, A would belong to no C: but (as we stated) it belongs to all C. Similarly also with the rest.
It is possible also to reduce all syllogisms to the universal syllogisms in the first figure.
30It is clear too that all the imperfect syllogisms are made perfect by means of the first figure. For all are brought to a conclusion either ostensively or per impossibile. In both ways the first figure is formed: if they are made perfect ostensively, because (as we saw) all are brought to a conclusion by means of conversion, and conversion produces the first figure: 35if they are proved per impossibile, because on the assumption of the false statement the syllogism comes about by means of the first figure, e.g. in the last figure, if A and B belong to all C, it follows that A belongs to some B: for if A belonged to no B, and B belongs to all C, A would belong to no C: but (as we stated) it belongs to all C. Similarly also with the rest.
It is possible also to reduce all syllogisms to the universal syllogisms in the first figure.
29b
1 Ἔστι δὲ καὶ ἀναγαγεῖν πάντας τοὺς συλλογισμοὺς εἰς
τοὺς ἐν τῷ πρώτῳ σχήματι καθόλου συλλογισμούς. οἱ μὲν
γὰρ ἐν τῷ δευτέρῳ φανερὸν ὅτι δι' ἐκείνων τελειοῦνται, πλὴν
οὐχ ὁμοίως πάντες, ἀλλ' οἱ μὲν καθόλου τοῦ στερητικοῦ ἀντιστραφέντος,
5 τῶν δ' ἐν μέρει ἑκάτερος διὰ τῆς εἰς τὸ ἀδύνατον
ἀπαγωγῆς. οἱ δ' ἐν τῷ πρώτῳ, οἱ κατὰ μέρος, ἐπιτελοῦνται
μὲν καὶ δι' αὑτῶν, ἔστι δὲ καὶ διὰ τοῦ δευτέρου σχήματος
δεικνύναι εἰς ἀδύνατον ἀπάγοντας, οἷον εἰ τὸ Α παντὶ τῷ Β,
τὸ δὲ Β τινὶ τῷ Γ, ὅτι τὸ Α τινὶ τῷ Γ· εἰ γὰρ μηδενί, τῷ
10 δὲ Β παντί, οὐδενὶ τῷ Γ τὸ Β ὑπάρξει· τοῦτο γὰρ ἴσμεν διὰ
τοῦ δευτέρου σχήματος. ὁμοίως δὲ καὶ ἐπὶ τοῦ στερητικοῦ ἔσται
ἡ ἀπόδειξις. εἰ γὰρ τὸ Α μηδενὶ τῷ Β, τὸ δὲ Β τινὶ τῷ Γ
ὑπάρχει, τὸ Α τινὶ τῷ Γ οὐχ ὑπάρξει· εἰ γὰρ παντί, τῷ δὲ
Β μηδενὶ ὑπάρχει, οὐδενὶ τῷ Γ τὸ Β ὑπάρξει· τοῦτο δ' ἦν τὸ
15 μέσον σχῆμα. ὥστ' ἐπεὶ οἱ μὲν ἐν τῷ μέσῳ σχήματι συλλογισμοὶ
πάντες ἀνάγονται εἰς τοὺς ἐν τῷ πρώτῳ καθόλου
συλλογισμούς, οἱ δὲ κατὰ μέρος ἐν τῷ πρώτῳ εἰς τοὺς ἐν
τῷ μέσῳ, φανερὸν ὅτι καὶ οἱ κατὰ μέρος ἀναχθήσονται εἰς
τοὺς ἐν τῷ πρώτῳ σχήματι καθόλου συλλογισμούς. οἱ δ'
20 ἐν τῷ τρίτῳ καθόλου μὲν ὄντων τῶν ὅρων εὐθὺς ἐπιτελοῦνται
δι' ἐκείνων τῶν συλλογισμῶν, ὅταν δ' ἐν μέρει ληφθῶσι, διὰ
τῶν ἐν μέρει συλλογισμῶν τῶν ἐν τῷ πρώτῳ σχήματι· οὗτοι
δὲ ἀνήχθησαν εἰς ἐκείνους, ὥστε καὶ οἱ ἐν τῷ τρίτῳ σχήματι,
οἱ κατὰ μέρος. φανερὸν οὖν ὅτι πάντες ἀναχθήσονται εἰς τοὺς
25 ἐν τῷ πρώτῳ σχήματι καθόλου συλλογισμούς.
Οἱ μὲν οὖν τῶν συλλογισμῶν ὑπάρχειν ἢ μὴ ὑπάρχειν
δεικνύντες εἴρηται πῶς ἔχουσι, καὶ καθ' ἑαυτοὺς οἱ ἐκ τοῦ αὐτοῦ
σχήματος καὶ πρὸς ἀλλήλους οἱ ἐκ τῶν ἑτέρων.
1Those in the second figure are clearly made perfect by these, though not all in the same way; the universal syllogisms are made perfect by converting the negative premiss, 5each of the particular syllogisms by reductio ad impossibile. In the first figure particular syllogisms are indeed made perfect by themselves, but it is possible also to prove them by means of the second figure, reducing them ad impossibile, e.g. if A belongs to all B, and B to some C, it follows that A belongs to some C. For if it belonged to no C, and belongs to all B, 10then B will belong to no C: this we know by means of the second figure. Similarly also demonstration will be possible in the case of the negative. For if A belongs to no B, and B belongs to some C, A will not belong to some C: for if it belonged to all C, and belongs to no B, then B will belong to no C: and this (as we saw) is 15the middle figure. Consequently, since all syllogisms in the middle figure can be reduced to universal syllogisms in the first figure, and since particular syllogisms in the first figure can be reduced to syllogisms in the middle figure, it is clear that particular syllogisms can be reduced to universal syllogisms in the first figure. 20Syllogisms in the third figure, if the terms are universal, are directly made perfect by means of those syllogisms; but, when one of the premisses is particular, by means of the particular syllogisms in the first figure: and these (we have seen) may be reduced to the universal syllogisms in the first figure: consequently also the particular syllogisms in the third figure may be so reduced. It is clear then that 25all syllogisms may be reduced to the universal syllogisms in the first figure.
We have stated then how syllogisms which prove that something belongs or does not belong to something else are constituted, both how syllogisms of the same figure are constituted in themselves, and how syllogisms of different figures are related to one another.
We have stated then how syllogisms which prove that something belongs or does not belong to something else are constituted, both how syllogisms of the same figure are constituted in themselves, and how syllogisms of different figures are related to one another.
Book 1,Chapter 8 (29b29–30a14)
Ἐπεὶ δ' ἕτερόν ἐστιν ὑπάρχειν τε καὶ ἐξ ἀνάγκης ὑπάρχειν
30 καὶ ἐνδέχεσθαι ὑπάρχειν (πολλὰ γὰρ ὑπάρχει μέν, οὐ
μέντοι ἐξ ἀνάγκης· τὰ δ' οὔτ' ἐξ ἀνάγκης οὔθ' ὑπάρχει ὅλως,
ἐνδέχεται δ' ὑπάρχειν), δῆλον ὅτι καὶ συλλογισμὸς ἑκάστου
τούτων ἕτερος ἔσται, καὶ οὐχ ὁμοίως ἐχόντων τῶν ὅρων, ἀλλ'
ὁ μὲν ἐξ ἀναγκαίων, ὁ δ' ἐξ ὑπαρχόντων, ὁ δ' ἐξ ἐνδεχομένων.
35
Ἐπὶ μὲν οὖν τῶν ἀναγκαίων σχεδὸν ὁμοίως ἔχει καὶ
ἐπὶ τῶν ὑπαρχόντων· ὡσαύτως γὰρ τιθεμένων τῶν ὅρων ἔν
τε τῷ ὑπάρχειν καὶ τῷ ἐξ ἀνάγκης ὑπάρχειν ἢ μὴ ὑπάρχειν
ἔσται τε καὶ οὐκ ἔσται συλλογισμός, πλὴν διοίσει τῷ
29Since there is a difference according as something belongs, necessarily belongs, 30or may belong to something else (for many things belong indeed, but not necessarily, others neither necessarily nor indeed at all, but it is possible for them to belong), it is clear that there will be different syllogisms to prove each of these relations, and syllogisms with differently related terms, one syllogism concluding from what is necessary, another from what is, a third from what is possible.
There is hardly any difference between 35syllogisms from necessary premisses and syllogisms from premisses which merely assert. When the terms are put in the same way, then, whether something belongs or necessarily belongs (or does not belong) to something else, a syllogism will or will not result alike in both cases, the only difference being the addition of the expression 'necessarily' to the terms.
There is hardly any difference between 35syllogisms from necessary premisses and syllogisms from premisses which merely assert. When the terms are put in the same way, then, whether something belongs or necessarily belongs (or does not belong) to something else, a syllogism will or will not result alike in both cases, the only difference being the addition of the expression 'necessarily' to the terms.
30a
1 προσκεῖσθαι τοῖς ὅροις τὸ ἐξ ἀνάγκης ὑπάρχειν ἢ μὴ ὑπάρχειν.
τό τε γὰρ στερητικὸν ὡσαύτως ἀντιστρέφει, καὶ τὸ ἐν
ὅλῳ εἶναι καὶ τὸ κατὰ παντὸς ὁμοίως ἀποδώσομεν. ἐν μὲν
οὖν τοῖς ἄλλοις τὸν αὐτὸν τρόπον δειχθήσεται διὰ τῆς ἀντιστροφῆς
5 τὸ συμπέρασμα ἀναγκαῖον, ὥσπερ ἐπὶ τοῦ ὑπάρχειν·
ἐν δὲ τῷ μέσῳ σχήματι, ὅταν ᾖ τὸ καθόλου καταφατικὸν
τὸ δ' ἐν μέρει στερητικόν, καὶ πάλιν ἐν τῷ τρίτῳ, ὅταν τὸ
μὲν καθόλου κατηγορικὸν τὸ δ' ἐν μέρει στερητικόν, οὐχ ὁμοίως
ἔσται ἡ ἀπόδειξις, ἀλλ' ἀνάγκη ἐκθεμένους ᾧ τινὶ ἑκάτερον
10 μὴ ὑπάρχει, κατὰ τούτου ποιεῖν τὸν συλλογισμόν· ἔσται γὰρ
ἀναγκαῖος ἐπὶ τούτων· εἰ δὲ κατὰ τοῦ ἐκτεθέντος ἐστὶν ἀναγκαῖος,
καὶ κατ' ἐκείνου τινός· τὸ γὰρ ἐκτεθὲν ὅπερ ἐκεῖνό τί
ἐστιν. γίνεται δὲ τῶν συλλογισμῶν ἑκάτερος ἐν τῷ οἰκείῳ
σχήματι.
1For the negative statement is convertible alike in both cases, and we should give the same account of the expressions 'to be contained in something as in a whole' and 'to be predicated of all of something'. With the exceptions to be made below, the conclusion will be proved to be necessary by means of conversion, 5in the same manner as in the case of simple predication. But in the middle figure when the universal statement is affirmative, and the particular negative, and again in the third figure when the universal is affirmative and the particular negative, the demonstration will not take the same form, but it is necessary by the 'exposition' of a part of the subject of the particular negative proposition, to which the predicate does not belong, 10to make the syllogism in reference to this: with terms so chosen the conclusion will necessarily follow. But if the relation is necessary in respect of the part taken, it must hold of some of that term in which this part is included: for the part taken is just some of that. And each of the resulting syllogisms is in the appropriate figure.
Book 1,Chapter 9 (30a15–30b6)
15 Συμβαίνει δέ ποτε καὶ τῆς ἑτέρας προτάσεως ἀναγκαίας
οὔσης ἀναγκαῖον γίνεσθαι τὸν συλλογισμόν, πλὴν οὐχ
ὁποτέρας ἔτυχεν, ἀλλὰ τῆς πρὸς τὸ μεῖζον ἄκρον, οἷον εἰ τὸ
μὲν Α τῷ Β ἐξ ἀνάγκης εἴληπται ὑπάρχον ἢ μὴ ὑπάρχον,
τὸ δὲ Β τῷ Γ ὑπάρχον μόνον· οὕτως γὰρ εἰλημμένων τῶν
20 προτάσεων ἐξ ἀνάγκης τὸ Α τῷ Γ ὑπάρξει ἢ οὐχ ὑπάρξει.
ἐπεὶ γὰρ παντὶ τῷ Β ἐξ ἀνάγκης ὑπάρχει ἢ οὐχ ὑπάρχει
τὸ Α, τὸ δὲ Γ τι τῶν Β ἐστί, φανερὸν ὅτι καὶ τῷ Γ ἐξ ἀνάγκης
ἔσται θάτερον τούτων. εἰ δὲ τὸ μὲν Α Β μὴ ἔστιν ἀναγκαῖον,
τὸ δὲ Β Γ ἀναγκαῖον, οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον.
25 εἰ γὰρ ἔστι, συμβήσεται τὸ Α τινὶ τῷ Β ὑπάρχειν
ἐξ ἀνάγκης διά τε τοῦ πρώτου καὶ διὰ τοῦ τρίτου σχήματος.
τοῦτο δὲ ψεῦδος· ἐνδέχεται γὰρ τοιοῦτον εἶναι τὸ Β ᾧ ἐγχωρεῖ
τὸ Α μηδενὶ ὑπάρχειν. ἔτι καὶ ἐκ τῶν ὅρων φανερὸν ὅτι
οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον, οἷον εἰ τὸ μὲν Α εἴη κίνησις,
30 τὸ δὲ Β ζῷον, ἐφ' ᾧ δὲ τὸ Γ ἄνθρωπος· ζῷον μὲν
γὰρ ὁ ἄνθρωπος ἐξ ἀνάγκης ἐστί, κινεῖται δὲ τὸ ζῷον οὐκ ἐξ
ἀνάγκης, οὐδ' ὁ ἄνθρωπος. ὁμοίως δὲ καὶ εἰ στερητικὸν εἴη
τὸ Α Β· ἡ γὰρ αὐτὴ ἀπόδειξις. ἐπὶ δὲ τῶν ἐν μέρει συλλογισμῶν,
εἰ μὲν τὸ καθόλου ἐστὶν ἀναγκαῖον, καὶ τὸ συμπέρασμα
35 ἔσται ἀναγκαῖον, εἰ δὲ τὸ κατὰ μέρος, οὐκ ἀναγκαῖον,
οὔτε στερητικῆς οὔτε κατηγορικῆς οὔσης τῆς καθόλου προτάσεως.
ἔστω δὴ πρῶτον τὸ καθόλου ἀναγκαῖον, καὶ τὸ μὲν
Α παντὶ τῷ Β ὑπαρχέτω ἐξ ἀνάγκης, τὸ δὲ Β τινὶ τῷ Γ
ὑπαρχέτω μόνον· ἀνάγκη δὴ τὸ Α τινὶ τῷ Γ ὑπάρχειν ἐξ
40 ἀνάγκης· τὸ γὰρ Γ ὑπὸ τὸ Β ἐστί, τῷ δὲ Β παντὶ
15It happens sometimes also that when one premiss is necessary the conclusion is necessary, not however when either premiss is necessary, but only when the major is, e.g. if A is taken as necessarily belonging or not belonging to B, but B is taken as simply belonging to C: for if the premisses are taken in this way, 20A will necessarily belong or not belong to C. For since necessarily belongs, or does not belong, to every B, and since C is one of the Bs, it is clear that for C also the positive or the negative relation to A will hold necessarily. But if the major premiss is not necessary, but the minor is necessary, the conclusion will not be necessary. 25For if it were, it would result both through the first figure and through the third that A belongs necessarily to some B. But this is false; for B may be such that it is possible that A should belong to none of it. Further, an example also makes it clear that the conclusion not be necessary, e.g. if A were movement, B animal, C man: 30man is an animal necessarily, but an animal does not move necessarily, nor does man. Similarly also if the major premiss is negative; for the proof is the same.
In particular syllogisms, if the universal premiss is necessary, then the conclusion will be necessary; 35but if the particular, the conclusion will not be necessary, whether the universal premiss is negative or affirmative. First let the universal be necessary, and let A belong to all B necessarily, but let B simply belong to some C: it is necessary then that A belongs to some C necessarily: 40for C falls under B, and A was assumed to belong necessarily to all B.
In particular syllogisms, if the universal premiss is necessary, then the conclusion will be necessary; 35but if the particular, the conclusion will not be necessary, whether the universal premiss is negative or affirmative. First let the universal be necessary, and let A belong to all B necessarily, but let B simply belong to some C: it is necessary then that A belongs to some C necessarily: 40for C falls under B, and A was assumed to belong necessarily to all B.
30b
1 ὑπῆρχεν ἐξ ἀνάγκης, ὁμοίως δὲ καὶ εἰ στερητικὸς εἴη ὁ συλλογισμός·
ἡ γὰρ αὐτὴ ἔσται ἀπόδειξις. εἰ δὲ τὸ κατὰ μέρος
ἐστὶν ἀναγκαῖον, οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον
(οὐδὲν γὰρ ἀδύνατον συμπίπτει), καθάπερ οὐδ' ἐν τοῖς καθόλου
5 συλλογισμοῖς. ὁμοίως δὲ κἀπὶ τῶν στερητικῶν. ὅροι κίνησις—ζῷον—λευκόν.
1Similarly also if the syllogism should be negative: for the proof will be the same. But if the particular premiss is necessary, the conclusion will not be necessary: for from the denial of such a conclusion nothing impossible results, just as it does not in the universal syllogisms. 5The same is true of negative syllogisms. Try the terms movement, animal, white.
Book 1,Chapter 10 (30b7–31a17)
Ἐπὶ δὲ τοῦ δευτέρου σχήματος, εἰ μὲν ἡ στερητικὴ πρότασίς
ἐστιν ἀναγκαία, καὶ τὸ συμπέρασμα ἔσται ἀναγκαῖον,
εἰ δ' ἡ κατηγορική, οὐκ ἀναγκαῖον. ἔστω γὰρ πρῶτον ἡ στερητικὴ
10 ἀναγκαία, καὶ τὸ Α τῷ μὲν Β μηδενὶ ἐνδεχέσθω, τῷ
δὲ Γ ὑπαρχέτω μόνον. ἐπεὶ οὖν ἀντιστρέφει τὸ στερητικόν, οὐδὲ
τὸ Β τῷ Α οὐδενὶ ἐνδέχεται· τὸ δὲ Α παντὶ τῷ Γ ὑπάρχει,
ὥστ' οὐδενὶ τῷ Γ τὸ Β ἐνδέχεται· τὸ γὰρ Γ ὑπὸ τὸ Α ἐστίν.
ὡσαύτως δὲ καὶ εἰ πρὸς τῷ Γ τεθείη τὸ στερητικόν· εἰ γὰρ τὸ
15 Α μηδενὶ τῷ Γ ἐνδέχεται, οὐδὲ τὸ Γ οὐδενὶ τῷ Α ἐγχωρεῖ·
τὸ δὲ Α παντὶ τῷ Β ὑπάρχει, ὥστ' οὐδενὶ τῷ Β τὸ Γ ἐνδέχεται·
γίνεται γὰρ τὸ πρῶτον σχῆμα πάλιν. οὐκ ἄρα οὐδὲ τὸ Β
τῷ Γ· ἀντιστρέφει γὰρ ὁμοίως. Εἰ δὲ ἡ κατηγορικὴ πρότασίς
ἐστιν ἀναγκαία, οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον.
20 ὑπαρχέτω γὰρ τὸ Α παντὶ τῷ Β ἐξ ἀνάγκης, τῷ δὲ Γ μηδενὶ
ὑπαρχέτω μόνον. ἀντιστραφέντος οὖν τοῦ στερητικοῦ τὸ πρῶτον
γίνεται σχῆμα· δέδεικται δ' ἐν τῷ πρώτῳ ὅτι μὴ ἀναγκαίας
οὔσης τῆς πρὸς τὸ μεῖζον στερητικῆς οὐδὲ τὸ συμπέρασμα
ἔσται ἀναγκαῖον, ὥστ' οὐδ' ἐπὶ τούτων ἔσται ἐξ ἀνάγκης. ἔτι δ'
25 εἰ τὸ συμπέρασμά ἐστιν ἀναγκαῖον, συμβαίνει τὸ Γ τινὶ τῷ
Α μὴ ὑπάρχειν ἐξ ἀνάγκης. εἰ γὰρ τὸ Β τῷ Γ μηδενὶ
ὑπάρχει ἐξ ἀνάγκης, οὐδὲ τὸ Γ τῷ Β οὐδενὶ ὑπάρξει ἐξ
ἀνάγκης. τὸ δέ γε Β τινὶ τῷ Α ἀνάγκη ὑπάρχειν, εἴπερ καὶ
τὸ Α παντὶ τῷ Β ἐξ ἀνάγκης ὑπῆρχεν. ὥστε τὸ Γ ἀνάγκη
30 τινὶ τῷ Α μὴ ὑπάρχειν. ἀλλ' οὐδὲν κωλύει τὸ Α τοιοῦτον ληφθῆναι
ᾧ παντὶ τὸ Γ ἐνδέχεται ὑπάρχειν. ἔτι κἂν ὅρους ἐκθέμενον
εἴη δεῖξαι ὅτι τὸ συμπέρασμα οὐκ ἔστιν ἀναγκαῖον
ἁπλῶς, ἀλλὰ τούτων ὄντων ἀναγκαῖον. οἷον ἔστω τὸ Α ζῷον,
τὸ δὲ Β ἄνθρωπος, τὸ δὲ Γ λευκόν, καὶ αἱ προτάσεις ὁμοίως
35 εἰλήφθωσαν· ἐνδέχεται γὰρ τὸ ζῷον μηδενὶ λευκῷ ὑπάρχειν.
οὐχ ὑπάρξει δὴ οὐδ' ὁ ἄνθρωπος οὐδενὶ λευκῷ, ἀλλ' οὐκ ἐξ
ἀνάγκης· ἐνδέχεται γὰρ ἄνθρωπον γενέσθαι λευκόν, οὐ μέντοι
ἕως ἂν ζῷον μηδενὶ λευκῷ ὑπάρχῃ. ὥστε τούτων μὲν ὄντων
ἀναγκαῖον ἔσται τὸ συμπέρασμα, ἁπλῶς δ' οὐκ ἀναγκαῖον.
40
7In the second figure, if the negative premiss is necessary, then the conclusion will be necessary, but if the affirmative, not necessary. First let the negative be 10necessary; let A be possible of no B, and simply belong to C. Since then the negative statement is convertible, B is possible of no A. But A belongs to all C; consequently B is possible of no C. For C falls under A. The same result would be obtained if the minor premiss were negative: for 15if A is possible be of no C, C is possible of no A: but A belongs to all B, consequently C is possible of none of the Bs: for again we have obtained the first figure. Neither then is B possible of C: for conversion is possible without modifying the relation.
But if the affirmative premiss is necessary, the conclusion will not be necessary. 20Let A belong to all B necessarily, but to no C simply. If then the negative premiss is converted, the first figure results. But it has been proved in the case of the first figure that if the negative major premiss is not necessary the conclusion will not be necessary either. Therefore the same result will obtain here. Further, 25if the conclusion is necessary, it follows that C necessarily does not belong to some A. For if B necessarily belongs to no C, C will necessarily belong to no B. But B at any rate must belong to some A, if it is true (as was assumed) that A necessarily belongs to all B. Consequently it is necessary that C does not belong to some A. 30But nothing prevents such an A being taken that it is possible for C to belong to all of it. Further one might show by an exposition of terms that the conclusion is not necessary without qualification, though it is a necessary conclusion from the premisses. For example let A be animal, B man, C white, and let the premisses be assumed to correspond to what we had before: 35it is possible that animal should belong to nothing white. Man then will not belong to anything white, but not necessarily: for it is possible for man to be born white, not however so long as animal belongs to nothing white. Consequently under these conditions the conclusion will be necessary, but it is not necessary without qualification.
Similar results will obtain also in particular syllogisms.
But if the affirmative premiss is necessary, the conclusion will not be necessary. 20Let A belong to all B necessarily, but to no C simply. If then the negative premiss is converted, the first figure results. But it has been proved in the case of the first figure that if the negative major premiss is not necessary the conclusion will not be necessary either. Therefore the same result will obtain here. Further, 25if the conclusion is necessary, it follows that C necessarily does not belong to some A. For if B necessarily belongs to no C, C will necessarily belong to no B. But B at any rate must belong to some A, if it is true (as was assumed) that A necessarily belongs to all B. Consequently it is necessary that C does not belong to some A. 30But nothing prevents such an A being taken that it is possible for C to belong to all of it. Further one might show by an exposition of terms that the conclusion is not necessary without qualification, though it is a necessary conclusion from the premisses. For example let A be animal, B man, C white, and let the premisses be assumed to correspond to what we had before: 35it is possible that animal should belong to nothing white. Man then will not belong to anything white, but not necessarily: for it is possible for man to be born white, not however so long as animal belongs to nothing white. Consequently under these conditions the conclusion will be necessary, but it is not necessary without qualification.
Similar results will obtain also in particular syllogisms.
31a
1 Ὁμοίως δ' ἕξει καὶ ἐπὶ τῶν ἐν μέρει συλλογισμῶν.
ὅταν μὲν γὰρ ἡ στερητικὴ πρότασις καθόλου τ' ᾖ καὶ ἀναγκαία,
καὶ τὸ συμπέρασμα ἔσται ἀναγκαῖον· ὅταν δὲ ἡ κατηγορικὴ
καθόλου, ἡ δὲ στερητικὴ κατὰ μέρος, οὐκ ἔσται τὸ
5 συμπέρασμα ἀναγκαῖον. ἔστω δὴ πρῶτον ἡ στερητικὴ καθόλου
τε καὶ ἀναγκαία, καὶ τὸ Α τῷ μὲν Β μηδενὶ ἐνδεχέσθω
ὑπάρχειν, τῷ δὲ Γ τινὶ ὑπαρχέτω. ἐπεὶ οὖν ἀντιστρέφει
τὸ στερητικόν, οὐδὲ τὸ Β τῷ Α οὐδενὶ ἐνδέχοιτ' ἂν ὑπάρχειν·
τὸ δέ γε Α τινὶ τῷ Γ ὑπάρχει, ὥστ' ἐξ ἀνάγκης τινὶ τῷ Γ
10 οὐχ ὑπάρξει τὸ Β. πάλιν ἔστω ἡ κατηγορικὴ καθόλου τε καὶ
ἀναγκαία, καὶ κείσθω πρὸς τῷ Β τὸ κατηγορικόν. εἰ δὴ τὸ
Α παντὶ τῷ Β ἐξ ἀνάγκης ὑπάρχει, τῷ δὲ Γ τινὶ μὴ ὑπάρχει,
ὅτι μὲν οὐχ ὑπάρξει τὸ Β τινὶ τῷ Γ, φανερόν, ἀλλ' οὐκ
ἐξ ἀνάγκης· οἱ γὰρ αὐτοὶ ὅροι ἔσονται πρὸς τὴν ἀπόδειξιν
15 οἵπερ ἐπὶ τῶν καθόλου συλλογισμῶν. ἀλλ' οὐδ' εἰ τὸ στερητικὸν
ἀναγκαῖόν ἐστιν ἐν μέρει ληφθέν, οὐκ ἔσται τὸ συμπέρασμα
ἀναγκαῖον· διὰ γὰρ τῶν αὐτῶν ὅρων ἡ ἀπόδειξις.
1For whenever the negative premiss is both universal and necessary, then the conclusion will be necessary: but whenever the affirmative premiss is universal, the negative particular, the conclusion will not be necessary. 5First then let the negative premiss be both universal and necessary: let it be possible for no B that A should belong to it, and let A simply belong to some C. Since the negative statement is convertible, it will be possible for no A that B should belong to it: but A belongs to some C; consequently B necessarily does not belong to some of the Cs. 10Again let the affirmative premiss be both universal and necessary, and let the major premiss be affirmative. If then A necessarily belongs to all B, but does not belong to some C, it is clear that B will not belong to some C, but not necessarily. For the same terms can be used to demonstrate the point, which were used in the universal syllogisms. 15Nor again, if the negative statement is necessary but particular, will the conclusion be necessary. The point can be demonstrated by means of the same terms.
Book 1,Chapter 11 (31a18–32a5)
Ἐν δὲ τῷ τελευταίῳ σχήματι καθόλου μὲν ὄντων τῶν
ὅρων πρὸς τὸ μέσον καὶ κατηγορικῶν ἀμφοτέρων τῶν προτάσεων,
20 ἐὰν ὁποτερονοῦν ᾖ ἀναγκαῖον, καὶ τὸ συμπέρασμα
ἔσται ἀναγκαῖον. ἐὰν δὲ τὸ μὲν ᾖ στερητικὸν τὸ δὲ κατηγορικόν,
ὅταν μὲν τὸ στερητικὸν ἀναγκαῖον ᾖ, καὶ τὸ συμπέρασμα
ἔσται ἀναγκαῖον, ὅταν δὲ τὸ κατηγορικόν, οὐκ ἔσται ἀναγκαῖον.
ἔστωσαν γὰρ ἀμφότεραι κατηγορικαὶ πρῶτον αἱ προτάσεις,
25 καὶ τὸ Α καὶ τὸ Β παντὶ τῷ Γ ὑπαρχέτω, ἀναγκαῖον
δ' ἔστω τὸ Α Γ. ἐπεὶ οὖν τὸ Β παντὶ τῷ Γ ὑπάρχει,
καὶ τὸ Γ τινὶ τῷ Β ὑπάρξει διὰ τὸ ἀντιστρέφειν τὸ καθόλου
τῷ κατὰ μέρος, ὥστ' εἰ παντὶ τῷ Γ τὸ Α ἐξ ἀνάγκης ὑπάρχει
καὶ τὸ Γ τῷ Β τινί, καὶ τῷ Β τινὶ ἀναγκαῖον ὑπάρχειν
30 τὸ Α· τὸ γὰρ Β ὑπὸ τὸ Γ ἐστίν. γίγνεται οὖν τὸ πρῶτον σχῆμα.
ὁμοίως δὲ δειχθήσεται καὶ εἰ τὸ Β Γ ἐστὶν ἀναγκαῖον· ἀντιστρέφει
γὰρ τὸ Γ τῷ Α τινί, ὥστ' εἰ παντὶ τῷ Γ τὸ Β ἐξ
ἀνάγκης ὑπάρχει, καὶ τῷ Α τινὶ ὑπάρξει ἐξ ἀνάγκης. Πάλιν
ἔστω τὸ μὲν Α Γ στερητικόν, τὸ δὲ Β Γ καταφατικόν,
35 ἀναγκαῖον δὲ τὸ στερητικόν. ἐπεὶ οὖν ἀντιστρέφει τινὶ τῷ Β τὸ Γ,
τὸ δὲ Α οὐδενὶ τῷ Γ ἐξ ἀνάγκης, οὐδὲ τῷ Β τινὶ ὑπάρξει ἐξ ἀνάγκης
τὸ Α· τὸ γὰρ Β ὑπὸ τὸ Γ ἐστίν. εἰ δὲ τὸ κατηγορικὸν ἀναγκαῖον,
οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον. ἔστω γὰρ τὸ Β Γ
κατηγορικὸν καὶ ἀναγκαῖον, τὸ δὲ Α Γ στερητικὸν καὶ μὴ ἀναγκαῖον.
40 ἐπεὶ οὖν ἀντιστρέφει τὸ καταφατικόν, ὑπάρξει καὶ τὸ
Γ τινὶ τῷ Β ἐξ ἀνάγκης, ὥστ' εἰ τὸ μὲν Α μηδενὶ τῷ Γ τὸ
18In the last figure when the terms are related universally to the middle, and both premisses are affirmative, 20if one of the two is necessary, then the conclusion will be necessary. But if one is negative, the other affirmative, whenever the negative is necessary the conclusion also will be necessary, but whenever the affirmative is necessary the conclusion will not be necessary. First let both the premisses be affirmative, 25and let A and B belong to all C, and let Ac be necessary. Since then B belongs to all C, C also will belong to some B, because the universal is convertible into the particular: consequently if A belongs necessarily to all C, and C belongs to some B, it is necessary that A should belong to some B also. 30For B is under C. The first figure then is formed. A similar proof will be given also if BC is necessary. For C is convertible with some A: consequently if B belongs necessarily to all C, it will belong necessarily also to some A.
Again let AC be negative, BC affirmative, 35and let the negative premiss be necessary. Since then C is convertible with some B, but A necessarily belongs to no C, A will necessarily not belong to some B either: for B is under C. But if the affirmative is necessary, the conclusion will not be necessary. For suppose BC is affirmative and necessary, while AC is negative and not necessary. 40Since then the affirmative is convertible, C also will belong to some B necessarily: consequently if A belongs to none of the Cs, while C belongs to some of the Bs, A will not belong to some of the Bs-but not of necessity; for it has been proved, in the case of the first figure, that if the negative premiss is not necessary, neither will the conclusion be necessary.
Again let AC be negative, BC affirmative, 35and let the negative premiss be necessary. Since then C is convertible with some B, but A necessarily belongs to no C, A will necessarily not belong to some B either: for B is under C. But if the affirmative is necessary, the conclusion will not be necessary. For suppose BC is affirmative and necessary, while AC is negative and not necessary. 40Since then the affirmative is convertible, C also will belong to some B necessarily: consequently if A belongs to none of the Cs, while C belongs to some of the Bs, A will not belong to some of the Bs-but not of necessity; for it has been proved, in the case of the first figure, that if the negative premiss is not necessary, neither will the conclusion be necessary.
31b
1 δὲ Γ τινὶ τῷ Β, τὸ Α τινὶ τῷ Β οὐχ ὑπάρξει· ἀλλ' οὐκ ἐξ
ἀνάγκης· δέδεικται γὰρ ἐν τῷ πρώτῳ σχήματι ὅτι τῆς στερητικῆς
προτάσεως μὴ ἀναγκαίας οὔσης οὐδὲ τὸ συμπέρασμα
ἔσται ἀναγκαῖον. ἔτι κἂν διὰ τῶν ὅρων εἴη φανερόν. ἔστω γὰρ
5 τὸ μὲν Α ἀγαθόν, τὸ δ' ἐφ' ᾧ Β ζῷον, τὸ δὲ Γ ἵππος. τὸ
μὲν οὖν ἀγαθὸν ἐνδέχεται μηδενὶ ἵππῳ ὑπάρχειν, τὸ δὲ ζῷον
ἀνάγκη παντὶ ὑπάρχειν· ἀλλ' οὐκ ἀνάγκη ζῷόν τι μὴ εἶναι
ἀγαθόν, εἴπερ ἐνδέχεται πᾶν εἶναι ἀγαθόν. ἢ εἰ μὴ τοῦτο δυνατόν,
ἀλλὰ τὸ ἐγρηγορέναι ἢ τὸ καθεύδειν ὅρον θετέον· ἅπαν
10 γὰρ ζῷον δεκτικὸν τούτων.
Εἰ μὲν οὖν οἱ ὅροι καθόλου πρὸς τὸ μέσον εἰσίν, εἴρηται
πότε ἔσται τὸ συμπέρασμα ἀναγκαῖον· εἰ δ' ὁ μὲν καθόλου
ὁ δ' ἐν μέρει, κατηγορικῶν μὲν ὄντων ἀμφοτέρων, ὅταν τὸ
καθόλου γένηται ἀναγκαῖον, καὶ τὸ συμπέρασμα ἔσται ἀναγκαῖον.
15 ἀπόδειξις δ' ἡ αὐτὴ ἣ καὶ πρότερον· ἀντιστρέφει γὰρ
καὶ τὸ ἐν μέρει κατηγορικόν. εἰ οὖν ἀνάγκη τὸ Β παντὶ τῷ
Γ ὑπάρχειν, τὸ δὲ Α ὑπὸ τὸ Γ ἐστίν, ἀνάγκη τὸ Β τινὶ τῷ
Α ὑπάρχειν. εἰ δὲ τὸ Β τῷ Α τινί, καὶ τὸ Α τῷ Β τινὶ
ὑπάρχειν ἀναγκαῖον· ἀντιστρέφει γάρ. ὁμοίως δὲ καὶ εἰ τὸ Α
20 Γ εἴη ἀναγκαῖον καθόλου ὄν· τὸ γὰρ Β ὑπὸ τὸ Γ ἐστίν. εἰ δὲ
τὸ ἐν μέρει ἐστὶν ἀναγκαῖον, οὐκ ἔσται τὸ συμπέρασμα ἀναγκαῖον.
ἔστω γὰρ τὸ Β Γ ἐν μέρει τε καὶ ἀναγκαῖον, τὸ δὲ Α
παντὶ τῷ Γ ὑπαρχέτω, μὴ μέντοι ἐξ ἀνάγκης. ἀντιστραφέντος
οὖν τοῦ Β Γ τὸ πρῶτον γίγνεται σχῆμα, καὶ ἡ μὲν καθόλου
25 πρότασις οὐκ ἀναγκαία, ἡ δ' ἐν μέρει ἀναγκαία. ὅτε
δ' οὕτως ἔχοιεν αἱ προτάσεις, οὐκ ἦν τὸ συμπέρασμα ἀναγκαῖον,
ὥστ' οὐδ' ἐπὶ τούτων. ἔτι δὲ καὶ ἐκ τῶν ὅρων φανερόν.
ἔστω γὰρ τὸ μὲν Α ἐγρήγορσις, τὸ δὲ Β δίπουν, ἐφ' ᾧ δὲ τὸ Γ
ζῷον. τὸ μὲν οὖν Β τινὶ τῷ Γ ἀνάγκη ὑπάρχειν, τὸ δὲ Α τῷ
30 Γ ἐνδέχεται, καὶ τὸ Α τῷ Β οὐκ ἀναγκαῖον· οὐ γὰρ ἀνάγκη
δίπουν τι καθεύδειν ἢ ἐγρηγορέναι. ὁμοίως δὲ καὶ διὰ τῶν
αὐτῶν ὅρων δειχθήσεται καὶ εἰ τὸ Α Γ εἴη ἐν μέρει τε καὶ
ἀναγκαῖον. Εἰ δ' ὁ μὲν κατηγορικὸς ὁ δὲ στερητικὸς τῶν ὅρων,
ὅταν μὲν ᾖ τὸ καθόλου στερητικόν τε καὶ ἀναγκαῖον, καὶ τὸ
35 συμπέρασμα ἔσται ἀναγκαῖον· εἰ γὰρ τὸ Α τῷ Γ μηδενὶ ἐνδέχεται,
τὸ δὲ Β τινὶ τῷ Γ ὑπάρχει, τὸ Α τινὶ τῷ Β ἀνάγκη
μὴ ὑπάρχειν. ὅταν δὲ τὸ καταφατικὸν ἀναγκαῖον τεθῇ, ἢ
καθόλου ὂν ἢ ἐν μέρει, ἢ τὸ στερητικὸν κατὰ μέρος, οὐκ ἔσται
τὸ συμπέρασμα ἀναγκαῖον. τὰ μὲν γὰρ ἄλλα ταὐτὰ ἃ καὶ
40 ἐπὶ τῶν πρότερον ἐροῦμεν, ὅροι δ' ὅταν μὲν ᾖ καθόλου τὸ κατηγορικὸν
ἀναγκαῖον, ἐγρήγορσις—ζῷον—ἄνθρωπος, μέσον ἄνθρωπος,
1Further, the point may be made clear by considering the terms. 5Let the term A be 'good', let that which B signifies be 'animal', let the term C be 'horse'. It is possible then that the term good should belong to no horse, and it is necessary that the term animal should belong to every horse: but it is not necessary that some animal should not be good, since it is possible for every animal to be good. Or if that is not possible, take as the term 'awake' or 'asleep': 10for every animal can accept these.
If, then, the premisses are universal, we have stated when the conclusion will be necessary. But if one premiss is universal, the other particular, and if both are affirmative, whenever the universal is necessary the conclusion also must be necessary. 15The demonstration is the same as before; for the particular affirmative also is convertible. If then it is necessary that B should belong to all C, and A falls under C, it is necessary that B should belong to some A. But if B must belong to some A, then A must belong to some B: for conversion is possible. 20Similarly also if AC should be necessary and universal: for B falls under C. But if the particular premiss is necessary, the conclusion will not be necessary. Let the premiss BC be both particular and necessary, and let A belong to all C, not however necessarily. If the proposition BC is converted the first figure is formed, and 25the universal premiss is not necessary, but the particular is necessary. But when the premisses were thus, the conclusion (as we proved was not necessary: consequently it is not here either. Further, the point is clear if we look at the terms. Let A be waking, B biped, and C animal. It is necessary that B should belong to some C, but 30it is possible for A to belong to C, and that A should belong to B is not necessary. For there is no necessity that some biped should be asleep or awake. Similarly and by means of the same terms proof can be made, should the proposition Ac be both particular and necessary.
But if one premiss is affirmative, the other negative, whenever the universal is both negative and necessary 35the conclusion also will be necessary. For if it is not possible that A should belong to any C, but B belongs to some C, it is necessary that A should not belong to some B. But whenever the affirmative proposition is necessary, whether universal or particular, or the negative is particular, the conclusion will not be necessary. The proof of this by reduction will be the same as before; 40but if terms are wanted, when the universal affirmative is necessary, take the terms 'waking'-'animal'-'man', 'man' being middle, and when the affirmative is particular and necessary, take the terms 'waking'-'animal'-'white': for it is necessary that animal should belong to some white thing, but it is possible that waking should belong to none, and it is not necessary that waking should not belong to some animal.
If, then, the premisses are universal, we have stated when the conclusion will be necessary. But if one premiss is universal, the other particular, and if both are affirmative, whenever the universal is necessary the conclusion also must be necessary. 15The demonstration is the same as before; for the particular affirmative also is convertible. If then it is necessary that B should belong to all C, and A falls under C, it is necessary that B should belong to some A. But if B must belong to some A, then A must belong to some B: for conversion is possible. 20Similarly also if AC should be necessary and universal: for B falls under C. But if the particular premiss is necessary, the conclusion will not be necessary. Let the premiss BC be both particular and necessary, and let A belong to all C, not however necessarily. If the proposition BC is converted the first figure is formed, and 25the universal premiss is not necessary, but the particular is necessary. But when the premisses were thus, the conclusion (as we proved was not necessary: consequently it is not here either. Further, the point is clear if we look at the terms. Let A be waking, B biped, and C animal. It is necessary that B should belong to some C, but 30it is possible for A to belong to C, and that A should belong to B is not necessary. For there is no necessity that some biped should be asleep or awake. Similarly and by means of the same terms proof can be made, should the proposition Ac be both particular and necessary.
But if one premiss is affirmative, the other negative, whenever the universal is both negative and necessary 35the conclusion also will be necessary. For if it is not possible that A should belong to any C, but B belongs to some C, it is necessary that A should not belong to some B. But whenever the affirmative proposition is necessary, whether universal or particular, or the negative is particular, the conclusion will not be necessary. The proof of this by reduction will be the same as before; 40but if terms are wanted, when the universal affirmative is necessary, take the terms 'waking'-'animal'-'man', 'man' being middle, and when the affirmative is particular and necessary, take the terms 'waking'-'animal'-'white': for it is necessary that animal should belong to some white thing, but it is possible that waking should belong to none, and it is not necessary that waking should not belong to some animal.
32a
1 ὅταν δ' ἐν μέρει τὸ κατηγορικὸν ἀναγκαῖον, ἐγρήγορσις—ζῷον—λευκόν·
ζῷον μὲν γὰρ ἀνάγκη τινὶ λευκῷ ὑπάρχειν,
ἐγρήγορσις δ' ἐνδέχεται μηδενί, καὶ οὐκ ἀνάγκη τινὶ
ζῴῳ μὴ ὑπάρχειν ἐγρήγορσιν. ὅταν δὲ τὸ στερητικὸν ἐν μέρει
5 ὂν ἀναγκαῖον ᾖ, δίπουν—κινούμενον—ζῷον, μέσον ζῷον.
1But when the negative proposition being particular is necessary, 5take the terms 'biped', 'moving', 'animal', 'animal' being middle.
Book 1,Chapter 12 (32a6–14)
Φανερὸν οὖν ὅτι τοῦ μὲν ὑπάρχειν οὐκ ἔστι συλλογισμός,
ἐὰν μὴ ἀμφότεραι ὦσιν αἱ προτάσεις ἐν τῷ ὑπάρχειν, τοῦ
δ' ἀναγκαίου ἔστι καὶ τῆς ἑτέρας μόνον ἀναγκαίας οὔσης. ἐν
ἀμφοτέροις δέ, καὶ καταφατικῶν καὶ στερητικῶν ὄντων τῶν
10 συλλογισμῶν, ἀνάγκη τὴν ἑτέραν πρότασιν ὁμοίαν εἶναι τῷ
συμπεράσματι. λέγω δὲ τὸ ὁμοίαν, εἰ μὲν ὑπάρχον, ὑπάρχουσαν,
εἰ δ' ἀναγκαῖον, ἀναγκαίαν. ὥστε καὶ τοῦτο δῆλον,
ὅτι οὐκ ἔσται τὸ συμπέρασμα οὔτ' ἀναγκαῖον οὔθ' ὑπάρχον εἶναι
μὴ ληφθείσης ἀναγκαίας ἢ ὑπαρχούσης προτάσεως.
6It is clear then that a simple conclusion is not reached unless both premisses are simple assertions, but a necessary conclusion is possible although one only of the premisses is necessary. But in both cases, whether the syllogisms are affirmative or negative, 10it is necessary that one premiss should be similar to the conclusion. I mean by 'similar', if the conclusion is a simple assertion, the premiss must be simple; if the conclusion is necessary, the premiss must be necessary. Consequently this also is clear, that the conclusion will be neither necessary nor simple unless a necessary or simple premiss is assumed.
Book 1,Chapter 13 (32a15–32b37)
15 Περὶ μὲν οὖν τοῦ ἀναγκαίου, πῶς γίγνεται καὶ τίνα διαφορὰν
ἔχει πρὸς τὸ ὑπάρχον, εἴρηται σχεδὸν ἱκανῶς· περὶ δὲ
τοῦ ἐνδεχομένου μετὰ ταῦτα λέγωμεν πότε καὶ πῶς καὶ διὰ
τίνων ἔσται συλλογισμός. λέγω δ' ἐνδέχεσθαι καὶ τὸ ἐνδεχόμενον,
οὗ μὴ ὄντος ἀναγκαίου, τεθέντος δ' ὑπάρχειν, οὐδὲν ἔσται
20 διὰ τοῦτ' ἀδύνατον· τὸ γὰρ ἀναγκαῖον ὁμωνύμως ἐνδέχεσθαι
λέγομεν. [ὅτι δὲ τοῦτ' ἔστι τὸ ἐνδεχόμενον, φανερὸν ἔκ τε τῶν
ἀποφάσεων καὶ τῶν καταφάσεων τῶν ἀντικειμένων· τὸ γὰρ
οὐκ ἐνδέχεται ὑπάρχειν καὶ ἀδύνατον ὑπάρχειν καὶ ἀνάγκη
μὴ ὑπάρχειν ἤτοι ταὐτά ἐστιν ἢ ἀκολουθεῖ ἀλλήλοις, ὥστε
25 καὶ τὰ ἀντικείμενα, τὸ ἐνδέχεται ὑπάρχειν καὶ οὐκ
ἀδύνατον ὑπάρχειν καὶ οὐκ ἀνάγκη μὴ ὑπάρχειν, ἤτοι
ταὐτὰ ἔσται ἢ ἀκολουθοῦντα ἀλλήλοις· κατὰ παντὸς γὰρ ἡ
φάσις ἢ ἡ ἀπόφασις. ἔσται ἄρα τὸ ἐνδεχόμενον οὐκ
ἀναγκαῖον καὶ τὸ μὴ ἀναγκαῖον ἐνδεχόμενον.] συμβαίνει
30 δὲ πάσας τὰς κατὰ τὸ ἐνδέχεσθαι προτάσεις ἀντιστρέφειν
ἀλλήλαις. λέγω δὲ οὐ τὰς καταφατικὰς ταῖς ἀποφατικαῖς,
ἀλλ' ὅσαι καταφατικὸν ἔχουσι τὸ σχῆμα κατὰ τὴν ἀντίθεσιν,
οἷον τὸ ἐνδέχεσθαι ὑπάρχειν τῷ ἐνδέχεσθαι μὴ ὑπάρχειν, καὶ
τὸ παντὶ ἐνδέχεσθαι τῷ ἐνδέχεσθαι μηδενὶ καὶ μὴ παντί, καὶ
35 τὸ τινὶ τῷ μὴ τινί. τὸν αὐτὸν δὲ τρόπον καὶ ἐπὶ τῶν ἄλλων.
ἐπεὶ γὰρ τὸ ἐνδεχόμενον οὐκ ἔστιν ἀναγκαῖον, τὸ δὲ μὴ ἀναγκαῖον
ἐγχωρεῖ μὴ ὑπάρχειν, φανερὸν ὅτι, εἰ ἐνδέχεται τὸ
Α τῷ Β ὑπάρχειν, ἐνδέχεται καὶ μὴ ὑπάρχειν· καὶ εἰ
παντὶ ἐνδέχεται ὑπάρχειν, καὶ παντὶ ἐνδέχεται μὴ ὑπάρχειν.
40 ὁμοίως δὲ κἀπὶ τῶν ἐν μέρει καταφάσεων· ἡ γὰρ αὐτὴ
15Perhaps enough has been said about the proof of necessity, how it comes about and how it differs from the proof of a simple statement. We proceed to discuss that which is possible, when and how and by what means it can be proved. I use the terms 'to be possible' and 'the possible' of that which is not necessary but, being assumed, results in nothing impossible. 20We say indeed ambiguously of the necessary that it is possible. But that my definition of the possible is correct is clear from the phrases by which we deny or on the contrary affirm possibility. For the expressions 'it is not possible to belong', 'it is impossible to belong', and 'it is necessary not to belong' are either identical or follow from one another; 25consequently their opposites also, 'it is possible to belong', 'it is not impossible to belong', and 'it is not necessary not to belong', will either be identical or follow from one another. For of everything the affirmation or the denial holds good. That which is possible then will be not necessary and that which is not necessary will be possible. It results that 30all premisses in the mode of possibility are convertible into one another. I mean not that the affirmative are convertible into the negative, but that those which are affirmative in form admit of conversion by opposition, e.g. 'it is possible to belong' may be converted into 'it is possible not to belong', and 'it is possible for A to belong to all B' into 'it is possible for A to belong to no B' or 'not to all B', and 35'it is possible for A to belong to some B' into 'it is possible for A not to belong to some B'. And similarly the other propositions in this mode can be converted. 40For since that which is possible is not necessary, and that which is not necessary may possibly not belong, it is clear that if it is possible that A should belong to B, it is possible also that it should not belong to B: and if it is possible that it should belong to all, it is also possible that it should not belong to all.
32b
1 ἀπόδειξις. εἰσὶ δ' αἱ τοιαῦται προτάσεις κατηγορικαὶ καὶ
οὐ στερητικαί· τὸ γὰρ ἐνδέχεσθαι τῷ εἶναι ὁμοίως τάττεται,
καθάπερ ἐλέχθη πρότερον.
Διωρισμένων δὲ τούτων πάλιν λέγωμεν ὅτι τὸ ἐνδέχεσθαι
5 κατὰ δύο λέγεται τρόπους, ἕνα μὲν τὸ ὡς ἐπὶ τὸ
πολὺ γίνεσθαι καὶ διαλείπειν τὸ ἀναγκαῖον, οἷον τὸ πολιοῦσθαι
ἄνθρωπον ἢ τὸ αὐξάνεσθαι ἢ φθίνειν, ἢ ὅλως τὸ πεφυκὸς
ὑπάρχειν (τοῦτο γὰρ οὐ συνεχὲς μὲν ἔχει τὸ ἀναγκαῖον
διὰ τὸ μὴ ἀεὶ εἶναι ἄνθρωπον, ὄντος μέντοι ἀνθρώπου ἢ ἐξ
10 ἀνάγκης ἢ ὡς ἐπὶ τὸ πολύ ἐστιν), ἄλλον δὲ τὸ ἀόριστον, ὃ καὶ
οὕτως καὶ μὴ οὕτως δυνατόν, οἷον τὸ βαδίζειν ζῷον ἢ
βαδίζοντος γενέσθαι σεισμόν, ἢ ὅλως τὸ ἀπὸ τύχης γινόμενον·
οὐδὲν γὰρ μᾶλλον οὕτως πέφυκεν ἢ ἐναντίως. ἀντιστρέφει
μὲν οὖν καὶ κατὰ τὰς ἀντικειμένας προτάσεις ἑκάτερον
15 τῶν ἐνδεχομένων, οὐ μὴν τὸν αὐτόν γε τρόπον, ἀλλὰ τὸ μὲν
πεφυκὸς εἶναι τῷ μὴ ἐξ ἀνάγκης ὑπάρχειν (οὕτω γὰρ ἐνδέχεται
μὴ πολιοῦσθαι ἄνθρωπον), τὸ δ' ἀόριστον τῷ μηδὲν μᾶλλον
οὕτως ἢ ἐκείνως. ἐπιστήμη δὲ καὶ συλλογισμὸς ἀποδεικτικὸς
τῶν μὲν ἀορίστων οὐκ ἔστι διὰ τὸ ἄτακτον εἶναι τὸ μέσον,
20 τῶν δὲ πεφυκότων ἔστι, καὶ σχεδὸν οἱ λόγοι καὶ αἱ σκέψεις
γίνονται περὶ τῶν οὕτως ἐνδεχομένων· ἐκείνων δ' ἐγχωρεῖ μὲν
γενέσθαι συλλογισμόν, οὐ μὴν εἴωθέ γε ζητεῖσθαι.
Ταῦτα μὲν οὖν διορισθήσεται μᾶλλον ἐν τοῖς ἑπομένοις·
νῦν δὲ λέγωμεν πότε καὶ πῶς καὶ τίς ἔσται συλλογισμὸς ἐκ τῶν
25 ἐνδεχομένων προτάσεων. ἐπεὶ δὲ τὸ ἐνδέχεσθαι τόδε τῷδε
ὑπάρχειν διχῶς ἔστιν ἐκλαβεῖν· ἢ γὰρ ᾧ ὑπάρχει τόδε ἢ ᾧ
ἐνδέχεται αὐτὸ ὑπάρχειν—τὸ γάρ, καθ' οὗ τὸ Β, τὸ Α ἐνδέχεσθαι
τούτων σημαίνει θάτερον, ἢ καθ' οὗ λέγεται τὸ Β
ἢ καθ' οὗ ἐνδέχεται λέγεσθαι· τὸ δέ, καθ' οὗ τὸ Β, τὸ Α
30 ἐνδέχεσθαι ἢ παντὶ τῷ Β τὸ Α ἐγχωρεῖν οὐδὲν διαφέρει—
φανερὸν ὅτι διχῶς ἂν λέγοιτο τὸ Α τῷ Β παντὶ ἐνδέχεσθαι
ὑπάρχειν. πρῶτον οὖν εἴπωμεν, εἰ καθ' οὗ τὸ Γ τὸ Β ἐνδέχεται,
καὶ καθ' οὗ τὸ Β τὸ Α, τίς ἔσται καὶ ποῖος συλλογισμός·
οὕτω γὰρ αἱ προτάσεις ἀμφότεραι λαμβάνονται
35 κατὰ τὸ ἐνδέχεσθαι, ὅταν δὲ καθ' οὗ τὸ Β ὑπάρχει τὸ Α
ἐνδέχηται, ἡ μὲν ὑπάρχουσα ἡ δ' ἐνδεχομένη. ὥστ' ἀπὸ
τῶν ὁμοιοσχημόνων ἀρκτέον, καθάπερ καὶ ἐν τοῖς ἄλλοις.
1The same holds good in the case of particular affirmations: for the proof is identical. And such premisses are affirmative and not negative; for 'to be possible' is in the same rank as 'to be', as was said above.
Having made these distinctions we next point out that the expression 'to be possible' 5is used in two ways. In one it means to happen generally and fall short of necessity, e.g. man's turning grey or growing or decaying, or generally what naturally belongs to a thing (for this has not its necessity unbroken, since man's existence is not continuous for ever, although if a man does exist, it comes about either necessarily or generally). 10In another sense the expression means the indefinite, which can be both thus and not thus, e.g. an animal's walking or an earthquake's taking place while it is walking, or generally what happens by chance: for none of these inclines by nature in the one way more than in the opposite.
That which is possible in each of its two senses is convertible into its opposite, 15not however in the same way: but what is natural is convertible because it does not necessarily belong (for in this sense it is possible that a man should not grow grey) and what is indefinite is convertible because it inclines this way no more than that. Science and demonstrative syllogism are not concerned with things which are indefinite, because the middle term is uncertain; 20but they are concerned with things that are natural, and as a rule arguments and inquiries are made about things which are possible in this sense. Syllogisms indeed can be made about the former, but it is unusual at any rate to inquire about them.
These matters will be treated more definitely in the sequel; our business at present is to state the moods and nature of the syllogism made 25from possible premisses. The expression 'it is possible for this to belong to that' may be understood in two senses: 'that' may mean either that to which 'that' belongs or that to which it may belong; for the expression 'A is possible of the subject of B' means that it is possible either of that of which B is stated 30or of that of which B may possibly be stated. It makes no difference whether we say, A is possible of the subject of B, or all B admits of A. It is clear then that the expression 'A may possibly belong to all B' might be used in two senses. First then we must state the nature and characteristics of the syllogism which arises if B is possible of the subject of C, and A is possible of the subject of B. For thus both premisses are assumed 35in the mode of possibility; but whenever A is possible of that of which B is true, one premiss is a simple assertion, the other a problematic. Consequently we must start from premisses which are similar in form, as in the other cases.
Having made these distinctions we next point out that the expression 'to be possible' 5is used in two ways. In one it means to happen generally and fall short of necessity, e.g. man's turning grey or growing or decaying, or generally what naturally belongs to a thing (for this has not its necessity unbroken, since man's existence is not continuous for ever, although if a man does exist, it comes about either necessarily or generally). 10In another sense the expression means the indefinite, which can be both thus and not thus, e.g. an animal's walking or an earthquake's taking place while it is walking, or generally what happens by chance: for none of these inclines by nature in the one way more than in the opposite.
That which is possible in each of its two senses is convertible into its opposite, 15not however in the same way: but what is natural is convertible because it does not necessarily belong (for in this sense it is possible that a man should not grow grey) and what is indefinite is convertible because it inclines this way no more than that. Science and demonstrative syllogism are not concerned with things which are indefinite, because the middle term is uncertain; 20but they are concerned with things that are natural, and as a rule arguments and inquiries are made about things which are possible in this sense. Syllogisms indeed can be made about the former, but it is unusual at any rate to inquire about them.
These matters will be treated more definitely in the sequel; our business at present is to state the moods and nature of the syllogism made 25from possible premisses. The expression 'it is possible for this to belong to that' may be understood in two senses: 'that' may mean either that to which 'that' belongs or that to which it may belong; for the expression 'A is possible of the subject of B' means that it is possible either of that of which B is stated 30or of that of which B may possibly be stated. It makes no difference whether we say, A is possible of the subject of B, or all B admits of A. It is clear then that the expression 'A may possibly belong to all B' might be used in two senses. First then we must state the nature and characteristics of the syllogism which arises if B is possible of the subject of C, and A is possible of the subject of B. For thus both premisses are assumed 35in the mode of possibility; but whenever A is possible of that of which B is true, one premiss is a simple assertion, the other a problematic. Consequently we must start from premisses which are similar in form, as in the other cases.
Book 1,Chapter 14 (32b38–33b24)
Ὅταν οὖν τὸ Α παντὶ τῷ Β ἐνδέχηται καὶ τὸ Β παντὶ
τῷ Γ, συλλογισμὸς ἔσται τέλειος ὅτι τὸ Α παντὶ τῷ Γ ἐνδέχεται
40 ὑπάρχειν. τοῦτο δὲ φανερὸν ἐκ τοῦ ὁρισμοῦ· τὸ γὰρ
38Whenever A may possibly belong to all B, and B to all C, there will be a perfect syllogism to prove that A may possibly belong to all C.
33a
1 ἐνδέχεσθαι παντὶ ὑπάρχειν οὕτως ἐλέγομεν. ὁμοίως δὲ καὶ
εἰ τὸ μὲν Α ἐνδέχεται μηδενὶ τῷ Β, τὸ δὲ Β παντὶ τῷ Γ,
ὅτι τὸ Α ἐνδέχεται μηδενὶ τῷ Γ· τὸ γὰρ καθ' οὗ τὸ Β ἐνδέχεται,
τὸ Α μὴ ἐνδέχεσθαι, τοῦτ' ἦν τὸ μηδὲν ἀπολείπειν
5 τῶν ὑπὸ τὸ Β ἐνδεχομένων. ὅταν δὲ τὸ Α παντὶ τῷ Β ἐνδέχηται,
τὸ δὲ Β ἐνδέχηται μηδενὶ τῷ Γ, διὰ μὲν τῶν εἰλημμένων
προτάσεων οὐδεὶς γίνεται συλλογισμός, ἀντιστραφείσης
δὲ τῆς Β Γ κατὰ τὸ ἐνδέχεσθαι γίνεται ὁ αὐτὸς
ὅσπερ πρότερον. ἐπεὶ γὰρ ἐνδέχεται τὸ Β μηδενὶ τῷ Γ ὑπάρχειν,
10 ἐνδέχεται καὶ παντὶ ὑπάρχειν· τοῦτο δ' εἴρηται πρότερον.
ὥστ' εἰ τὸ μὲν Β παντὶ τῷ Γ, τὸ δ' Α παντὶ τῷ Β,
πάλιν ὁ αὐτὸς γίνεται συλλογισμός. ὁμοίως δὲ καὶ εἰ πρὸς
ἀμφοτέρας τὰς προτάσεις ἡ ἀπόφασις τεθείη μετὰ τοῦ ἐνδέχεσθαι.
λέγω δ' οἷον εἰ τὸ Α ἐνδέχεται μηδενὶ τῷ Β καὶ
15 τὸ Β μηδενὶ τῷ Γ· διὰ μὲν γὰρ τῶν εἰλημμένων προτάσεων
οὐδεὶς γίνεται συλλογισμός, ἀντιστρεφομένων δὲ πάλιν ὁ αὐτὸς
ἔσται ὅσπερ καὶ πρότερον. φανερὸν οὖν ὅτι τῆς ἀποφάσεως
τιθεμένης πρὸς τὸ ἔλαττον ἄκρον ἢ πρὸς ἀμφοτέρας τὰς
προτάσεις ἢ οὐ γίνεται συλλογισμὸς ἢ γίνεται μὲν ἀλλ'
20 οὐ τέλειος· ἐκ γὰρ τῆς ἀντιστροφῆς περαίνεται τὸ ἀναγκαῖον.
Ἐὰν δ' ἡ μὲν καθόλου τῶν προτάσεων ἡ δ' ἐν μέρει ληφθῇ,
πρὸς μὲν τὸ μεῖζον ἄκρον κειμένης τῆς καθόλου συλλογισμὸς
ἔσται [τέλειος]. εἰ γὰρ τὸ Α παντὶ τῷ Β ἐνδέχεται, τὸ δὲ Β
τινὶ τῷ Γ, τὸ Α τινὶ τῷ Γ ἐνδέχεται. τοῦτο δὲ φανερὸν ἐκ τοῦ
25 ὁρισμοῦ τοῦ ἐνδέχεσθαι. πάλιν εἰ τὸ Α ἐνδέχεται μηδενὶ τῷ Β,
τὸ δὲ Β τινὶ τῷ Γ ἐνδέχεται ὑπάρχειν, ἀνάγκη τὸ Α ἐνδέχεσθαί
τινι τῶν Γ μὴ ὑπάρχειν. ἀπόδειξις δ' ἡ αὐτή. ἐὰν δὲ στερητικὴ
ληφθῇ ἡ ἐν μέρει πρότασις, ἡ δὲ καθόλου καταφατική,
τῇ δὲ θέσει ὁμοίως ἔχωσιν (οἷον τὸ μὲν Α παντὶ τῷ Β ἐνδέχεται,
30 τὸ δὲ Β τινὶ τῷ Γ ἐνδέχεται μὴ ὑπάρχειν), διὰ μὲν
τῶν εἰλημμένων προτάσεων οὐ γίνεται φανερὸς συλλογισμός,
ἀντιστραφείσης δὲ τῆς ἐν μέρει καὶ τεθέντος τοῦ Β τινὶ τῷ Γ
ἐνδέχεσθαι ὑπάρχειν τὸ αὐτὸ ἔσται συμπέρασμα ὃ καὶ πρότερον,
καθάπερ ἐν τοῖς ἐξ ἀρχῆς. Ἐὰν δ' ἡ πρὸς τὸ μεῖζον
35 ἄκρον ἐν μέρει ληφθῇ, ἡ δὲ πρὸς τὸ ἔλαττον καθόλου, ἐάν
τ' ἀμφότεραι καταφατικαὶ τεθῶσιν ἐάν τε στερητικαὶ ἐάν τε
μὴ ὁμοιοσχήμονες, ἐάν τ' ἀμφότεραι ἀδιόριστοι ἢ κατὰ μέρος,
οὐδαμῶς ἔσται συλλογισμός· οὐδὲν γὰρ κωλύει τὸ Β
ὑπερτείνειν τοῦ Α καὶ μὴ κατηγορεῖσθαι ἐπ' ἴσων· ᾧ δ' ὑπερτείνει
40 τὸ Β τοῦ Α, εἰλήφθω τὸ Γ· τούτῳ γὰρ οὔτε παντὶ
1This is clear from the definition: for it was in this way that we explained 'to be possible for one term to belong to all of another'. Similarly if it is possible for A to belong no B, and for B to belong to all C, then it is possible for A to belong to no C. For the statement that it is possible for A not to belong to that of which B may be true means (as we saw) that none of those things which can possibly fall under the term B is left out of account. 5But whenever A may belong to all B, and B may belong to no C, then indeed no syllogism results from the premisses assumed, but if the premiss BC is converted after the manner of problematic propositions, the same syllogism results as before. For since it is possible that B should belong to no C, 10it is possible also that it should belong to all C. This has been stated above. Consequently if B is possible for all C, and A is possible for all B, the same syllogism again results. Similarly if in both the premisses the negative is joined with 'it is possible': e.g. if A may belong to none of the Bs, 15and B to none of the Cs. No syllogism results from the assumed premisses, but if they are converted we shall have the same syllogism as before. It is clear then that if the minor premiss is negative, or if both premisses are negative, either no syllogism results, 20or if one it is not perfect. For the necessity results from the conversion.
But if one of the premisses is universal, the other particular, when the major premiss is universal there will be a perfect syllogism. For if A is possible for all B, and B for some C, then A is possible for some C. This is clear from the 25definition of being possible. Again if A may belong to no B, and B may belong to some of the Cs, it is necessary that A may possibly not belong to some of the Cs. The proof is the same as above. But if the particular premiss is negative, and the universal is affirmative, the major still being universal and the minor particular, e.g. A is possible for all B, 30B may possibly not belong to some C, then a clear syllogism does not result from the assumed premisses, but if the particular premiss is converted and it is laid down that B possibly may belong to some C, we shall have the same conclusion as before, as in the cases given at the beginning.
35But if the major premiss is the minor universal, whether both are affirmative, or negative, or different in quality, or if both are indefinite or particular, in no way will a syllogism be possible. For nothing prevents B from reaching beyond A, so that as predicates cover unequal areas. 40Let C be that by which B extends beyond A.
But if one of the premisses is universal, the other particular, when the major premiss is universal there will be a perfect syllogism. For if A is possible for all B, and B for some C, then A is possible for some C. This is clear from the 25definition of being possible. Again if A may belong to no B, and B may belong to some of the Cs, it is necessary that A may possibly not belong to some of the Cs. The proof is the same as above. But if the particular premiss is negative, and the universal is affirmative, the major still being universal and the minor particular, e.g. A is possible for all B, 30B may possibly not belong to some C, then a clear syllogism does not result from the assumed premisses, but if the particular premiss is converted and it is laid down that B possibly may belong to some C, we shall have the same conclusion as before, as in the cases given at the beginning.
35But if the major premiss is the minor universal, whether both are affirmative, or negative, or different in quality, or if both are indefinite or particular, in no way will a syllogism be possible. For nothing prevents B from reaching beyond A, so that as predicates cover unequal areas. 40Let C be that by which B extends beyond A.
33b
1 οὔτε μηδενὶ οὔτε τινὶ οὔτε μή τινι ἐνδέχεται τὸ Α ὑπάρχειν, εἴπερ
ἀντιστρέφουσιν αἱ κατὰ τὸ ἐνδέχεσθαι προτάσεις καὶ τὸ
Β πλείοσιν ἐνδέχεται ἢ τὸ Α ὑπάρχειν. ἔτι δὲ καὶ ἐκ τῶν
ὅρων φανερόν· οὕτω γὰρ ἐχουσῶν τῶν προτάσεων τὸ πρῶτον
5 τῷ ἐσχάτῳ καὶ οὐδενὶ ἐνδέχεται καὶ παντὶ ὑπάρχειν ἀναγκαῖον.
ὅροι δὲ κοινοὶ πάντων τοῦ μὲν ὑπάρχειν ἐξ ἀνάγκης
ζῷον—λευκόν—ἄνθρωπος, τοῦ δὲ μὴ ἐνδέχεσθαι ζῷον—λευκόν—
ἱμάτιον. φανερὸν οὖν τοῦτον τὸν τρόπον ἐχόντων τῶν ὅρων ὅτι
οὐδεὶς γίνεται συλλογισμός. ἢ γὰρ τοῦ ὑπάρχειν ἢ τοῦ ἐξ
10 ἀνάγκης ἢ τοῦ ἐνδέχεσθαι πᾶς ἐστὶ συλλογισμός. τοῦ μὲν
οὖν ὑπάρχειν καὶ τοῦ ἀναγκαίου φανερὸν ὅτι οὐκ ἔστιν· ὁ μὲν
γὰρ καταφατικὸς ἀναιρεῖται τῷ στερητικῷ, ὁ δὲ στερητικὸς
τῷ καταφατικῷ. λείπεται δὴ τοῦ ἐνδέχεσθαι εἶναι· τοῦτο δ'
ἀδύνατον· δέδεικται γὰρ ὅτι οὕτως ἐχόντων τῶν ὅρων καὶ
15 παντὶ τῷ ἐσχάτῳ τὸ πρῶτον ἀνάγκη καὶ οὐδενὶ ἐνδέχεται
ὑπάρχειν. ὥστ' οὐκ ἂν εἴη τοῦ ἐνδέχεσθαι συλλογισμός· τὸ
γὰρ ἀναγκαῖον οὐκ ἦν ἐνδεχόμενον.
Φανερὸν δὲ ὅτι καθόλου τῶν ὅρων ὄντων ἐν ταῖς ἐνδεχομέναις
προτάσεσιν ἀεὶ γίνεται συλλογισμὸς ἐν τῷ πρώτῳ
20 σχήματι, καὶ κατηγορικῶν καὶ στερητικῶν ὄντων,
πλὴν κατηγορικῶν μὲν τέλειος, στερητικῶν δὲ ἀτελής. δεῖ
δὲ τὸ ἐνδέχεσθαι λαμβάνειν μὴ ἐν τοῖς ἀναγκαίοις, ἀλλὰ
κατὰ τὸν εἰρημένον διορισμόν. ἐνίοτε δὲ λανθάνει τὸ
τοιοῦτον.
1To C it is not possible that A should belong-either to all or to none or to some or not to some, since premisses in the mode of possibility are convertible and it is possible for B to belong to more things than A can. Further, this is obvious if we take terms; for if the premisses are as assumed, 5the major term is both possible for none of the minor and must belong to all of it. Take as terms common to all the cases under consideration 'animal'-'white'-'man', where the major belongs necessarily to the minor; 'animal'-'white'-'garment', where it is not possible that the major should belong to the minor. It is clear then that if the terms are related in this manner, no syllogism results. For every syllogism proves that something belongs either simply or necessarily 10or possibly. It is clear that there is no proof of the first or of the second. For the affirmative is destroyed by the negative, and the negative by the affirmative. There remains the proof of possibility. But this is impossible. For it has been proved that if the terms are related in this manner 15it is both necessary that the major should belong to all the minor and not possible that it should belong to any. Consequently there cannot be a syllogism to prove the possibility; for the necessary (as we stated) is not possible.
It is clear that if the terms are universal in possible premisses a syllogism always results in the 20first figure, whether they are affirmative or negative, only a perfect syllogism results in the first case, an imperfect in the second. But possibility must be understood according to the definition laid down, not as covering necessity. This is sometimes forgotten.
It is clear that if the terms are universal in possible premisses a syllogism always results in the 20first figure, whether they are affirmative or negative, only a perfect syllogism results in the first case, an imperfect in the second. But possibility must be understood according to the definition laid down, not as covering necessity. This is sometimes forgotten.
Book 1,Chapter 15 (33b25–35b22)
25 Ἐὰν δ' ἡ μὲν ὑπάρχειν ἡ δ' ἐνδέχεσθαι λαμβάνηται
τῶν προτάσεων, ὅταν μὲν ἡ πρὸς τὸ μεῖζον ἄκρον ἐνδέχεσθαι
σημαίνῃ, τέλειοί τ' ἔσονται πάντες οἱ συλλογισμοὶ καὶ τοῦ
ἐνδέχεσθαι κατὰ τὸν εἰρημένον διορισμόν, ὅταν δ' ἡ πρὸς τὸ
ἔλαττον, ἀτελεῖς τε πάντες, καὶ οἱ στερητικοὶ τῶν συλλογισμῶν
30 οὐ τοῦ κατὰ τὸν διορισμὸν ἐνδεχομένου, ἀλλὰ τοῦ μηδενὶ
ἢ μὴ παντὶ ἐξ ἀνάγκης ὑπάρχειν· εἰ γὰρ μηδενὶ ἢ μὴ
παντὶ ἐξ ἀνάγκης, ἐνδέχεσθαί φαμεν καὶ μηδενὶ καὶ μὴ
παντὶ ὑπάρχειν. ἐνδεχέσθω γὰρ τὸ Α παντὶ τῷ Β, τὸ δὲ
Β παντὶ τῷ Γ κείσθω ὑπάρχειν. ἐπεὶ οὖν ὑπὸ τὸ Β ἐστὶ τὸ
35 Γ, τῷ δὲ Β παντὶ ἐνδέχεται τὸ Α, φανερὸν ὅτι καὶ τῷ Γ
παντὶ ἐνδέχεται. γίνεται δὴ τέλειος συλλογισμός· ὁμοίως δὲ
καὶ στερητικῆς οὔσης τῆς Α Β προτάσεως, τῆς δὲ Β Γ καταφατικῆς,
καὶ τῆς μὲν ἐνδέχεσθαι τῆς δ' ὑπάρχειν λαμβανομένης,
τέλειος ἔσται συλλογισμὸς ὅτι τὸ Α ἐνδέχεται μηδενὶ τῷ
40 Γ ὑπάρχειν.
25If one premiss is a simple proposition, the other a problematic, whenever the major premiss indicates possibility all the syllogisms will be perfect and establish possibility in the sense defined; but whenever the minor premiss indicates possibility all the syllogisms will be imperfect, and those which are negative will establish not possibility according to the definition, 30but that the major does not necessarily belong to any, or to all, of the minor. For if this is so, we say it is possible that it should belong to none or not to all. Let A be possible for all B, and let B belong to all C. Since C falls under B, 35and A is possible for all B, clearly it is possible for all C also. So a perfect syllogism results. Likewise if the premiss AB is negative, and the premiss BC is affirmative, the former stating possible, the latter simple attribution, a perfect syllogism results 40proving that A possibly belongs to no C.
It is clear that perfect syllogisms result if the minor premiss states simple belonging: but that syllogisms will result if the modality of the premisses is reversed, must be proved per impossibile.
It is clear that perfect syllogisms result if the minor premiss states simple belonging: but that syllogisms will result if the modality of the premisses is reversed, must be proved per impossibile.
34a
1 Ὅτι μὲν οὖν τοῦ ὑπάρχειν τιθεμένου πρὸς τὸ ἔλαττον ἄκρον
τέλειοι γίγνονται συλλογισμοί, φανερόν· ὅτι δ' ἐναντίως ἔχοντος
ἔσονται συλλογισμοί, διὰ τοῦ ἀδυνάτου δεικτέον. ἅμα
δ' ἔσται δῆλον καὶ ὅτι ἀτελεῖς· ἡ γὰρ δεῖξις οὐκ ἐκ τῶν εἰλημμένων
5 προτάσεων. πρῶτον δὲ λεκτέον ὅτι εἰ τοῦ Α ὄντος
ἀνάγκη τὸ Β εἶναι, καὶ δυνατοῦ ὄντος τοῦ Α δυνατὸν ἔσται
καὶ τὸ Β ἐξ ἀνάγκης. ἔστω γὰρ οὕτως ἐχόντων τὸ μὲν ἐφ' ᾧ τὸ
Α δυνατόν, τὸ δ' ἐφ' ᾧ τὸ Β ἀδύνατον. εἰ οὖν τὸ μὲν δυνατόν,
ὅτε δυνατὸν εἶναι, γένοιτ' ἄν, τὸ δ' ἀδύνατον, ὅτ' ἀδύνατον,
10 οὐκ ἂν γένοιτο, ἅμα δ' εἴη τὸ Α δυνατὸν καὶ τὸ Β
ἀδύνατον, ἐνδέχοιτ' ἂν τὸ Α γενέσθαι ἄνευ τοῦ Β, εἰ δὲ γενέσθαι,
καὶ εἶναι· τὸ γὰρ γεγονός, ὅτε γέγονεν, ἔστιν. δεῖ δὲ
λαμβάνειν μὴ μόνον ἐν τῇ γενέσει τὸ ἀδύνατον καὶ δυνατόν,
ἀλλὰ καὶ ἐν τῷ ἀληθεύεσθαι καὶ ἐν τῷ ὑπάρχειν, καὶ ὁσαχῶς
15 ἄλλως λέγεται τὸ δυνατόν· ἐν ἅπασι γὰρ ὁμοίως ἕξει.
ἔτι τὸ ὄντος τοῦ Α τὸ Β εἶναι, οὐχ ὡς ἑνός τινος ὄντος τοῦ Α τὸ
Β ἔσται δεῖ ὑπολαβεῖν· οὐ γὰρ ἔστιν οὐδὲν ἐξ ἀνάγκης ἑνός
τινος ὄντος, ἀλλὰ δυοῖν ἐλαχίστοιν, οἷον ὅταν αἱ προτάσεις
οὕτως ἔχωσιν ὡς ἐλέχθη κατὰ τὸν συλλογισμόν. εἰ γὰρ τὸ
20 Γ κατὰ τοῦ Δ, τὸ δὲ Δ κατὰ τοῦ Ζ, καὶ τὸ Γ κατὰ τοῦ Ζ
ἐξ ἀνάγκης· καὶ εἰ δυνατὸν ἑκάτερον, καὶ τὸ συμπέρασμα
δυνατόν. ὥσπερ οὖν εἴ τις θείη τὸ μὲν Α τὰς προτάσεις, τὸ δὲ
Β τὸ συμπέρασμα, συμβαίνοι ἂν οὐ μόνον ἀναγκαίου τοῦ Α
ὄντος ἅμα καὶ τὸ Β εἶναι ἀναγκαῖον, ἀλλὰ καὶ δυνατοῦ δυνατόν.
25 Τούτου δὲ δειχθέντος, φανερὸν ὅτι ψεύδους ὑποτεθέντος
καὶ μὴ ἀδυνάτου καὶ τὸ συμβαῖνον διὰ τὴν ὑπόθεσιν
ψεῦδος ἔσται καὶ οὐκ ἀδύνατον. οἷον εἰ τὸ Α ψεῦδος μέν ἐστι
μὴ μέντοι ἀδύνατον, ὄντος δὲ τοῦ Α τὸ Β ἔστι, καὶ τὸ Β ἔσται
ψεῦδος μὲν οὐ μέντοι ἀδύνατον. ἐπεὶ γὰρ δέδεικται ὅτι εἰ
30 τοῦ Α ὄντος τὸ Β ἔστι, καὶ δυνατοῦ ὄντος τοῦ Α ἔσται τὸ Β δυνατόν,
ὑπόκειται δὲ τὸ Α δυνατὸν εἶναι, καὶ τὸ Β ἔσται δυνατόν·
εἰ γὰρ ἀδύνατον, ἅμα δυνατὸν ἔσται τὸ αὐτὸ καὶ
ἀδύνατον.
Διωρισμένων δὴ τούτων ὑπαρχέτω τὸ Α παντὶ τῷ Β,
35 τὸ δὲ Β παντὶ τῷ Γ ἐνδεχέσθω· ἀνάγκη οὖν τὸ Α παντὶ τῷ
Γ ἐνδέχεσθαι ὑπάρχειν. μὴ γὰρ ἐνδεχέσθω, τὸ δὲ Β παντὶ
τῷ Γ κείσθω ὡς ὑπάρχον· τοῦτο δὲ ψεῦδος μέν, οὐ μέντοι
ἀδύνατον. εἰ οὖν τὸ μὲν Α μὴ ἐνδέχεται παντὶ τῷ Γ, τὸ δὲ Β
παντὶ ὑπάρχει τῷ Γ, τὸ Α οὐ παντὶ τῷ Β ἐνδέχεται· γίνεται
40 γὰρ συλλογισμὸς διὰ τοῦ τρίτου σχήματος. ἀλλ' ὑπέκειτο
παντὶ ἐνδέχεσθαι ὑπάρχειν. ἀνάγκη ἄρα τὸ Α παντὶ
1At the same time it will be evident that they are imperfect: for the proof proceeds not from the premisses assumed. 5First we must state that if B's being follows necessarily from A's being, B's possibility will follow necessarily from A's possibility. Suppose, the terms being so related, that A is possible, and B is impossible. If then that which is possible, when it is possible for it to be, might happen, and if that which is impossible, when it is impossible, 10could not happen, and if at the same time A is possible and B impossible, it would be possible for A to happen without B, and if to happen, then to be. For that which has happened, when it has happened, is. But we must take the impossible and the possible not only in the sphere of becoming, but also in the spheres of truth and predicability, and 15the various other spheres in which we speak of the possible: for it will be alike in all. Further we must understand the statement that B's being depends on A's being, not as meaning that if some single thing A is, B will be: for nothing follows of necessity from the being of some one thing, but from two at least, i.e. when the premisses are related in the manner stated to be that of the syllogism. 20For if C is predicated of D, and D of F, then C is necessarily predicated of F. And if each is possible, the conclusion also is possible. If then, for example, one should indicate the premisses by A, and the conclusion by B, it would not only result that if A is necessary B is necessary, but also that if A is possible, B is possible.
25Since this is proved it is evident that if a false and not impossible assumption is made, the consequence of the assumption will also be false and not impossible: e.g. if A is false, but not impossible, and if B is the consequence of A, B also will be false but not impossible. For since it has been proved that 30if B's being is the consequence of A's being, then B's possibility will follow from A's possibility (and A is assumed to be possible), consequently B will be possible: for if it were impossible, the same thing would at the same time be possible and impossible.
Since we have defined these points, 35let A belong to all B, and B be possible for all C: it is necessary then that should be a possible attribute for all C. Suppose that it is not possible, but assume that B belongs to all C: this is false but not impossible. If then A is not possible for C but B belongs to all C, then A is not possible for all B: 40for a syllogism is formed in the third degree. But it was assumed that A is a possible attribute for all B.
25Since this is proved it is evident that if a false and not impossible assumption is made, the consequence of the assumption will also be false and not impossible: e.g. if A is false, but not impossible, and if B is the consequence of A, B also will be false but not impossible. For since it has been proved that 30if B's being is the consequence of A's being, then B's possibility will follow from A's possibility (and A is assumed to be possible), consequently B will be possible: for if it were impossible, the same thing would at the same time be possible and impossible.
Since we have defined these points, 35let A belong to all B, and B be possible for all C: it is necessary then that should be a possible attribute for all C. Suppose that it is not possible, but assume that B belongs to all C: this is false but not impossible. If then A is not possible for C but B belongs to all C, then A is not possible for all B: 40for a syllogism is formed in the third degree. But it was assumed that A is a possible attribute for all B.
34b
1 τῷ Γ ἐνδέχεσθαι· ψεύδους γὰρ τεθέντος καὶ οὐκ ἀδυνάτου τὸ
συμβαῖνόν ἐστιν ἀδύνατον. [ἐγχωρεῖ δὲ καὶ διὰ τοῦ πρώτου
σχήματος ποιῆσαι τὸ ἀδύνατον, θέντας τῷ Γ τὸ Β ὑπάρχειν.
εἰ γὰρ τὸ Β παντὶ τῷ Γ ὑπάρχει, τὸ δὲ Α παντὶ τῷ
5 Β ἐνδέχεται, κἂν τῷ Γ παντὶ ἐνδέχοιτο τὸ Α. ἀλλ' ὑπέκειτο
μὴ παντὶ ἐγχωρεῖν.]
Δεῖ δὲ λαμβάνειν τὸ παντὶ ὑπάρχον μὴ κατὰ χρόνον
ὁρίσαντας, οἷον νῦν ἢ ἐν τῷδε τῷ χρόνῳ, ἀλλ' ἁπλῶς· διὰ
τοιούτων γὰρ προτάσεων καὶ τοὺς συλλογισμοὺς ποιοῦμεν,
10 ἐπεὶ κατά γε τὸ νῦν λαμβανομένης τῆς προτάσεως οὐκ ἔσται
συλλογισμός· οὐδὲν γὰρ ἴσως κωλύει ποτὲ καὶ παντὶ κινουμένῳ
ἄνθρωπον ὑπάρχειν, οἷον εἰ μηδὲν ἄλλο κινοῖτο· τὸ δὲ
κινούμενον ἐνδέχεται παντὶ ἵππῳ· ἀλλ' ἄνθρωπον οὐδενὶ ἵππῳ
ἐνδέχεται. ἔτι ἔστω τὸ μὲν πρῶτον ζῷον, τὸ δὲ μέσον κινούμενον,
15 τὸ δ' ἔσχατον ἄνθρωπος. αἱ μὲν οὖν προτάσεις ὁμοίως
ἕξουσι, τὸ δὲ συμπέρασμα ἀναγκαῖον, οὐκ ἐνδεχόμενον· ἐξ
ἀνάγκης γὰρ ὁ ἄνθρωπος ζῷον. φανερὸν οὖν ὅτι τὸ καθόλου
ληπτέον ἁπλῶς, καὶ οὐ χρόνῳ διορίζοντας.
Πάλιν ἔστω στερητικὴ πρότασις καθόλου ἡ Α Β, καὶ
20 εἰλήφθω τὸ μὲν Α μηδενὶ τῷ Β ὑπάρχειν, τὸ δὲ Β παντὶ
ἐνδεχέσθω ὑπάρχειν τῷ Γ. τούτων οὖν τεθέντων ἀνάγκη τὸ Α
ἐνδέχεσθαι μηδενὶ τῷ Γ ὑπάρχειν. μὴ γὰρ ἐνδεχέσθω, τὸ
δὲ Β τῷ Γ κείσθω ὑπάρχον, καθάπερ πρότερον. ἀνάγκη δὴ
τὸ Α τινὶ τῷ Β ὑπάρχειν· γίνεται γὰρ συλλογισμὸς διὰ
25 τοῦ τρίτου σχήματος· τοῦτο δὲ ἀδύνατον. ὥστ' ἐνδέχοιτ' ἂν τὸ
Α μηδενὶ τῷ Γ· ψεύδους γὰρ τεθέντος ἀδύνατον τὸ συμβαῖνον.
οὗτος οὖν ὁ συλλογισμὸς οὐκ ἔστι τοῦ κατὰ τὸν διορισμὸν
ἐνδεχομένου, ἀλλὰ τοῦ μηδενὶ ἐξ ἀνάγκης (αὕτη γάρ ἐστιν ἡ
ἀντίφασις τῆς γενομένης ὑποθέσεως· ἐτέθη γὰρ ἐξ ἀνάγκης
30 τὸ Α τινὶ τῷ Γ ὑπάρχειν, ὁ δὲ διὰ τοῦ ἀδυνάτου συλλογισμὸς
τῆς ἀντικειμένης ἐστὶν φάσεως). ἔτι δὲ καὶ ἐκ τῶν
ὅρων φανερὸν ὅτι οὐκ ἔσται τὸ συμπέρασμα ἐνδεχόμενον. ἔστω
γὰρ τὸ μὲν Α κόραξ, τὸ δ' ἐφ' ᾧ Β διανοούμενον, ἐφ'
ᾧ δὲ Γ ἄνθρωπος. οὐδενὶ δὴ τῷ Β τὸ Α ὑπάρχει· οὐδὲν γὰρ
35 διανοούμενον κόραξ. τὸ δὲ Β παντὶ ἐνδέχεται τῷ Γ· παντὶ
γὰρ ἀνθρώπῳ τὸ διανοεῖσθαι. ἀλλὰ τὸ Α ἐξ ἀνάγκης οὐδενὶ
τῷ Γ· οὐκ ἄρα τὸ συμπέρασμα ἐνδεχόμενον. ἀλλ' οὐδ' ἀναγκαῖον
ἀεί. ἔστω γὰρ τὸ μὲν Α κινούμενον, τὸ δὲ Β ἐπιστήμη,
τὸ δ' ἐφ' ᾧ Γ ἄνθρωπος. τὸ μὲν οὖν Α οὐδενὶ τῷ Β ὑπάρξει,
40 τὸ δὲ Β παντὶ τῷ Γ ἐνδέχεται, καὶ οὐκ ἔσται τὸ συμπέρασμα
ἀναγκαῖον· οὐ γὰρ ἀνάγκη μηδένα κινεῖσθαι ἄνθρωπον, ἀλλ'
1It is necessary then that A is possible for all C. For though the assumption we made is false and not impossible, the conclusion is impossible. It is possible also in the first figure to bring about the impossibility, by assuming that B belongs to C. For if B belongs to all C, and A is possible for all B, 5then A would be possible for all C. But the assumption was made that A is not possible for all C.
We must understand 'that which belongs to all' with no limitation in respect of time, e.g. to the present or to a particular period, but simply without qualification. For it is by the help of such premisses that we make syllogisms, 10since if the premiss is understood with reference to the present moment, there cannot be a syllogism. For nothing perhaps prevents 'man' belonging at a particular time to everything that is moving, i.e. if nothing else were moving: but 'moving' is possible for every horse; yet 'man' is possible for no horse. Further let the major term be 'animal', the middle 'moving', the 15the minor 'man'. The premisses then will be as before, but the conclusion necessary, not possible. For man is necessarily animal. It is clear then that the universal must be understood simply, without limitation in respect of time.
Again let the premiss AB be universal and negative, and 20assume that A belongs to no B, but B possibly belongs to all C. These propositions being laid down, it is necessary that A possibly belongs to no C. Suppose that it cannot belong, and that B belongs to C, as above. It is necessary then that A belongs to some B: 25for we have a syllogism in the third figure: but this is impossible. Thus it will be possible for A to belong to no C; for if at is supposed false, the consequence is an impossible one. This syllogism then does not establish that which is possible according to the definition, but that which does not necessarily belong to any part of the subject (for this is the contradictory of the assumption which was made: 30for it was supposed that A necessarily belongs to some C, but the syllogism per impossibile establishes the contradictory which is opposed to this). Further, it is clear also from an example that the conclusion will not establish possibility. Let A be 'raven', B 'intelligent', and C 'man'. A then belongs to no B: for 35no intelligent thing is a raven. But B is possible for all C: for every man may possibly be intelligent. But A necessarily belongs to no C: so the conclusion does not establish possibility. But neither is it always necessary. Let A be 'moving', B 'science', C 'man'. 40A then will belong to no B; but B is possible for all C. And the conclusion will not be necessary.
We must understand 'that which belongs to all' with no limitation in respect of time, e.g. to the present or to a particular period, but simply without qualification. For it is by the help of such premisses that we make syllogisms, 10since if the premiss is understood with reference to the present moment, there cannot be a syllogism. For nothing perhaps prevents 'man' belonging at a particular time to everything that is moving, i.e. if nothing else were moving: but 'moving' is possible for every horse; yet 'man' is possible for no horse. Further let the major term be 'animal', the middle 'moving', the 15the minor 'man'. The premisses then will be as before, but the conclusion necessary, not possible. For man is necessarily animal. It is clear then that the universal must be understood simply, without limitation in respect of time.
Again let the premiss AB be universal and negative, and 20assume that A belongs to no B, but B possibly belongs to all C. These propositions being laid down, it is necessary that A possibly belongs to no C. Suppose that it cannot belong, and that B belongs to C, as above. It is necessary then that A belongs to some B: 25for we have a syllogism in the third figure: but this is impossible. Thus it will be possible for A to belong to no C; for if at is supposed false, the consequence is an impossible one. This syllogism then does not establish that which is possible according to the definition, but that which does not necessarily belong to any part of the subject (for this is the contradictory of the assumption which was made: 30for it was supposed that A necessarily belongs to some C, but the syllogism per impossibile establishes the contradictory which is opposed to this). Further, it is clear also from an example that the conclusion will not establish possibility. Let A be 'raven', B 'intelligent', and C 'man'. A then belongs to no B: for 35no intelligent thing is a raven. But B is possible for all C: for every man may possibly be intelligent. But A necessarily belongs to no C: so the conclusion does not establish possibility. But neither is it always necessary. Let A be 'moving', B 'science', C 'man'. 40A then will belong to no B; but B is possible for all C. And the conclusion will not be necessary.
35a
1 οὐκ ἀνάγκη τινά. δῆλον οὖν ὅτι τὸ συμπέρασμά ἐστι τοῦ μηδενὶ
ἐξ ἀνάγκης ὑπάρχειν. ληπτέον δὲ βέλτιον τοὺς ὅρους.
Ἐὰν δὲ τὸ στερητικὸν τεθῇ πρὸς τὸ ἔλαττον ἄκρον ἐνδέχεσθαι
σημαῖνον, ἐξ αὐτῶν μὲν τῶν εἰλημμένων προτάσεων
5 οὐδεὶς ἔσται συλλογισμός, ἀντιστραφείσης δὲ τῆς κατὰ τὸ
ἐνδέχεσθαι προτάσεως ἔσται, καθάπερ ἐν τοῖς πρότερον. ὑπαρχέτω
γὰρ τὸ Α παντὶ τῷ Β, τὸ δὲ Β ἐνδεχέσθω μηδενὶ
τῷ Γ. οὕτω μὲν οὖν ἐχόντων τῶν ὅρων οὐδὲν ἔσται ἀναγκαῖον·
ἐὰν δ' ἀντιστραφῇ τὸ Β Γ καὶ ληφθῇ τὸ Β παντὶ τῷ Γ ἐνδέχεσθαι,
10 γίνεται συλλογισμὸς ὥσπερ πρότερον· ὁμοίως γὰρ
ἔχουσιν οἱ ὅροι τῇ θέσει. τὸν αὐτὸν δὲ τρόπον καὶ στερητικῶν
ὄντων ἀμφοτέρων τῶν διαστημάτων, ἐὰν τὸ μὲν Α Β μὴ
ὑπάρχειν, τὸ δὲ Β Γ μηδενὶ ἐνδέχεσθαι σημαίνῃ· δι' αὐτῶν
μὲν γὰρ τῶν εἰλημμένων οὐδαμῶς γίνεται τὸ ἀναγκαῖον, ἀντιστραφείσης
15 δὲ τῆς κατὰ τὸ ἐνδέχεσθαι προτάσεως ἔσται
συλλογισμός. εἰλήφθω γὰρ τὸ μὲν Α μηδενὶ τῷ Β ὑπάρχειν,
τὸ δὲ Β ἐνδέχεσθαι μηδενὶ τῷ Γ. διὰ μὲν οὖν τούτων
οὐδὲν ἀναγκαῖον· ἐὰν δὲ ληφθῇ τὸ Β παντὶ τῷ Γ ἐνδέχεσθαι,
ὅπερ ἐστὶν ἀληθές, ἡ δὲ Α Β πρότασις ὁμοίως ἔχῃ, πάλιν
20 ὁ αὐτὸς ἔσται συλλογισμός. ἐὰν δὲ μὴ ὑπάρχειν τεθῇ τὸ Β
παντὶ τῷ Γ καὶ μὴ ἐνδέχεσθαι μὴ ὑπάρχειν, οὐκ ἔσται συλλογισμὸς
οὐδαμῶς, οὔτε στερητικῆς οὔσης οὔτε καταφατικῆς τῆς
Α Β προτάσεως. ὅροι δὲ κοινοὶ τοῦ μὲν ἐξ ἀνάγκης ὑπάρχειν
λευκόν—ζῷον—χιών, τοῦ δὲ μὴ ἐνδέχεσθαι λευκόν—ζῷον—πίττα.
25 Φανερὸν οὖν ὅτι καθόλου τῶν ὅρων ὄντων, καὶ τῆς μὲν
ὑπάρχειν τῆς δ' ἐνδέχεσθαι λαμβανομένης τῶν προτάσεων,
ὅταν ἡ πρὸς τὸ ἔλαττον ἄκρον ἐνδέχεσθαι λαμβάνηται πρότασις,
ἀεὶ γίνεται συλλογισμός, πλὴν ὁτὲ μὲν ἐξ αὐτῶν
ὁτὲ δ' ἀντιστραφείσης τῆς προτάσεως. πότε δὲ τούτων ἑκάτερος
30 καὶ διὰ τίν' αἰτίαν, εἰρήκαμεν. Ἐὰν δὲ τὸ μὲν καθόλου
τὸ δ' ἐν μέρει ληφθῇ τῶν διαστημάτων, ὅταν μὲν τὸ πρὸς
τὸ μεῖζον ἄκρον καθόλου τεθῇ καὶ ἐνδεχόμενον, εἴτ' ἀποφατικὸν
εἴτε καταφατικόν, τὸ δ' ἐν μέρει καταφατικὸν καὶ
ὑπάρχον, ἔσται συλλογισμὸς τέλειος, καθάπερ καὶ καθόλου
35 τῶν ὅρων ὄντων. ἀπόδειξις δ' ἡ αὐτὴ ἣ καὶ πρότερον. ὅταν
δὲ καθόλου μὲν ᾖ τὸ πρὸς τὸ μεῖζον ἄκρον, ὑπάρχον δὲ καὶ
μὴ ἐνδεχόμενον, θάτερον δ' ἐν μέρει καὶ ἐνδεχόμενον, ἐάν τ'
ἀποφατικαὶ ἐάν τε καταφατικαὶ τεθῶσιν ἀμφότεραι, ἐάν
τε ἡ μὲν ἀποφατικὴ ἡ δὲ καταφατική, πάντως ἔσται συλλογισμὸς
40 ἀτελής. πλὴν οἱ μὲν διὰ τοῦ ἀδυνάτου δειχθήσονται,
1For it is not necessary that no man should move; rather it is not necessary that any man should move. Clearly then the conclusion establishes that one term does not necessarily belong to any instance of another term. But we must take our terms better.
If the minor premiss is negative and indicates possibility, 5from the actual premisses taken there can be no syllogism, but if the problematic premiss is converted, a syllogism will be possible, as before. Let A belong to all B, and let B possibly belong to no C. If the terms are arranged thus, nothing necessarily follows: but if the proposition BC is converted and it is assumed that B is possible for all C, 10a syllogism results as before: for the terms are in the same relative positions. Likewise if both the relations are negative, if the major premiss states that A does not belong to B, and the minor premiss indicates that B may possibly belong to no C. Through the premisses actually taken nothing necessary results in any way; 15but if the problematic premiss is converted, we shall have a syllogism. Suppose that A belongs to no B, and B may possibly belong to no C. Through these comes nothing necessary. But if B is assumed to be possible for all C (and this is true) and if the premiss AB remains as before, 20we shall again have the same syllogism. But if it be assumed that B does not belong to any C, instead of possibly not belonging, there cannot be a syllogism anyhow, whether the premiss AB is negative or affirmative. As common instances of a necessary and positive relation we may take the terms white-animal-snow: of a necessary and negative relation, white-animal-pitch. 25Clearly then if the terms are universal, and one of the premisses is assertoric, the other problematic, whenever the minor premiss is problematic a syllogism always results, only sometimes it results from the premisses that are taken, sometimes it requires the conversion of one premiss. 30We have stated when each of these happens and the reason why. But if one of the relations is universal, the other particular, then whenever the major premiss is universal and problematic, whether affirmative or negative, and the particular is affirmative and assertoric, there will be a perfect syllogism, 35just as when the terms are universal. The demonstration is the same as before. But whenever the major premiss is universal, but assertoric, not problematic, and the minor is particular and problematic, whether both premisses are negative or affirmative, or one is negative, the other affirmative, in all cases 40there will be an imperfect syllogism.
If the minor premiss is negative and indicates possibility, 5from the actual premisses taken there can be no syllogism, but if the problematic premiss is converted, a syllogism will be possible, as before. Let A belong to all B, and let B possibly belong to no C. If the terms are arranged thus, nothing necessarily follows: but if the proposition BC is converted and it is assumed that B is possible for all C, 10a syllogism results as before: for the terms are in the same relative positions. Likewise if both the relations are negative, if the major premiss states that A does not belong to B, and the minor premiss indicates that B may possibly belong to no C. Through the premisses actually taken nothing necessary results in any way; 15but if the problematic premiss is converted, we shall have a syllogism. Suppose that A belongs to no B, and B may possibly belong to no C. Through these comes nothing necessary. But if B is assumed to be possible for all C (and this is true) and if the premiss AB remains as before, 20we shall again have the same syllogism. But if it be assumed that B does not belong to any C, instead of possibly not belonging, there cannot be a syllogism anyhow, whether the premiss AB is negative or affirmative. As common instances of a necessary and positive relation we may take the terms white-animal-snow: of a necessary and negative relation, white-animal-pitch. 25Clearly then if the terms are universal, and one of the premisses is assertoric, the other problematic, whenever the minor premiss is problematic a syllogism always results, only sometimes it results from the premisses that are taken, sometimes it requires the conversion of one premiss. 30We have stated when each of these happens and the reason why. But if one of the relations is universal, the other particular, then whenever the major premiss is universal and problematic, whether affirmative or negative, and the particular is affirmative and assertoric, there will be a perfect syllogism, 35just as when the terms are universal. The demonstration is the same as before. But whenever the major premiss is universal, but assertoric, not problematic, and the minor is particular and problematic, whether both premisses are negative or affirmative, or one is negative, the other affirmative, in all cases 40there will be an imperfect syllogism.
35b
1 οἱ δὲ καὶ διὰ τῆς ἀντιστροφῆς τῆς τοῦ ἐνδέχεσθαι, καθάπερ ἐν
τοῖς πρότερον. ἔσται δὲ συλλογισμὸς διὰ τῆς ἀντιστροφῆς [καὶ]
ὅταν ἡ μὲν καθόλου πρὸς τὸ μεῖζον ἄκρον τεθεῖσα σημαίνῃ
τὸ ὑπάρχειν [ἢ μὴ ὑπάρχειν], ἡ δ' ἐν μέρει στερητικὴ οὖσα
5 τὸ ἐνδέχεσθαι λαμβάνῃ, οἷον εἰ τὸ μὲν Α παντὶ τῷ Β ὑπάρχει
ἢ μὴ ὑπάρχει, τὸ δὲ Β τινὶ τῷ Γ ἐνδέχεται μὴ ὑπάρχειν·
ἀντιστραφέντος γὰρ τοῦ Β Γ κατὰ τὸ ἐνδέχεσθαι γίνεται
συλλογισμός. ὅταν δὲ τὸ μὴ ὑπάρχειν λαμβάνῃ ἡ κατὰ
μέρος τεθεῖσα, οὐκ ἔσται συλλογισμός. ὅροι τοῦ μὲν ὑπάρχειν
10 λευκόν—ζῷον—χιών, τοῦ δὲ μὴ ὑπάρχειν λευκόν—ζῷον—πίττα·
διὰ γὰρ τοῦ ἀδιορίστου ληπτέον τὴν ἀπόδειξιν. ἐὰν δὲ τὸ καθόλου
τεθῇ πρὸς τὸ ἔλαττον ἄκρον, τὸ δ' ἐν μέρει πρὸς τὸ μεῖζον,
ἐάν τε στερητικὸν ἐάν τε καταφατικόν, ἐάν τ' ἐνδεχόμενον ἐάν
θ' ὑπάρχον ὁποτερονοῦν, οὐδαμῶς ἔσται συλλογισμός. Οὐδ'
15 ὅταν ἐν μέρει ἢ ἀδιόριστοι τεθῶσιν αἱ προτάσεις, εἴτ' ἐνδέχεσθαι
λαμβάνουσαι εἴθ' ὑπάρχειν εἴτ' ἐναλλάξ, οὐδ' οὕτως
ἔσται συλλογισμός. ἀπόδειξις δ' ἡ αὐτὴ ἥπερ κἀπὶ τῶν πρότερον.
ὅροι δὲ κοινοὶ τοῦ μὲν ὑπάρχειν ἐξ ἀνάγκης ζῷον—λευκόν—ἄνθρωπος,
τοῦ δὲ μὴ ἐνδέχεσθαι ζῷον—λευκόν—ἱμάτιον.
20 φανερὸν οὖν ὅτι τοῦ μὲν πρὸς τὸ μεῖζον ἄκρον καθόλου τεθέντος
ἀεὶ γίνεται συλλογισμός, τοῦ δὲ πρὸς τὸ ἔλαττον οὐδέποτ'
οὐδενός.
1Only some of them will be proved per impossibile, others by the conversion of the problematic premiss, as has been shown above. And a syllogism will be possible by means of conversion when the major premiss is universal and assertoric, whether positive or negative, 5and the minor particular, negative, and problematic, e.g. if A belongs to all B or to no B, and B may possibly not belong to some C. For if the premiss BC is converted in respect of possibility, a syllogism results. But whenever the particular premiss is assertoric and negative, there cannot be a syllogism. As instances of the positive relation 10we may take the terms white-animal-snow; of the negative, white-animal-pitch. For the demonstration must be made through the indefinite nature of the particular premiss. But if the minor premiss is universal, and the major particular, whether either premiss is negative or affirmative, problematic or assertoric, nohow is a syllogism possible. 15Nor is a syllogism possible when the premisses are particular or indefinite, whether problematic or assertoric, or the one problematic, the other assertoric. The demonstration is the same as above. As instances of the necessary and positive relation we may take the terms animal-white-man; of the necessary and negative relation, animal-white-garment. 20It is evident then that if the major premiss is universal, a syllogism always results, but if the minor is universal nothing at all can ever be proved.
Book 1,Chapter 16 (35b23–36b25)
Ὅταν δ' ἡ μὲν ἐξ ἀνάγκης ὑπάρχειν ἡ δ' ἐνδέχεσθαι
σημαίνῃ τῶν προτάσεων, ὁ μὲν συλλογισμὸς ἔσται τὸν αὐτὸν
25 τρόπον ἐχόντων τῶν ὅρων, καὶ τέλειος ὅταν πρὸς τῷ ἐλάττονι
ἄκρῳ τεθῇ τὸ ἀναγκαῖον· τὸ δὲ συμπέρασμα κατηγορικῶν
μὲν ὄντων τῶν ὅρων τοῦ ἐνδέχεσθαι καὶ οὐ τοῦ ὑπάρχειν
ἔσται, καὶ καθόλου καὶ μὴ καθόλου τιθεμένων, ἐὰν δ' ᾖ τὸ μὲν
καταφατικὸν τὸ δὲ στερητικόν, ὅταν μὲν ᾖ τὸ καταφατικὸν
30 ἀναγκαῖον, τοῦ ἐνδέχεσθαι καὶ οὐ τοῦ μὴ ὑπάρχειν, ὅταν δὲ
τὸ στερητικόν, καὶ τοῦ ἐνδέχεσθαι μὴ ὑπάρχειν καὶ τοῦ μὴ
ὑπάρχειν, καὶ καθόλου καὶ μὴ καθόλου τῶν ὅρων ὄντων· τὸ
δ' ἐνδέχεσθαι ἐν τῷ συμπεράσματι τὸν αὐτὸν τρόπον ληπτέον
ὅνπερ καὶ ἐν τοῖς πρότερον. τοῦ δ' ἐξ ἀνάγκης μὴ ὑπάρχειν οὐκ
35 ἔσται συλλογισμός· ἕτερον γὰρ τὸ μὴ ἐξ ἀνάγκης ὑπάρχειν
καὶ τὸ ἐξ ἀνάγκης μὴ ὑπάρχειν.
Ὅτι μὲν οὖν καταφατικῶν ὄντων τῶν ὅρων οὐ γίνεται τὸ
συμπέρασμα ἀναγκαῖον, φανερόν. ὑπαρχέτω γὰρ τὸ μὲν Α
παντὶ τῷ Β ἐξ ἀνάγκης, τὸ δὲ Β ἐνδεχέσθω παντὶ τῷ Γ.
40 ἔσται δὴ συλλογισμὸς ἀτελὴς ὅτι ἐνδέχεται τὸ Α παντὶ τῷ Γ
23Whenever one premiss is necessary, the other problematic, there will be a syllogism when 25the terms are related as before; and a perfect syllogism when the minor premiss is necessary. If the premisses are affirmative the conclusion will be problematic, not assertoric, whether the premisses are universal or not: but if one is affirmative, the other negative, when 30the affirmative is necessary the conclusion will be problematic, not negative assertoric; but when the negative is necessary the conclusion will be problematic negative, and assertoric negative, whether the premisses are universal or not. Possibility in the conclusion must be understood in the same manner as before. There cannot be an inference to the necessary negative proposition: 35for 'not necessarily to belong' is different from 'necessarily not to belong'.
If the premisses are affirmative, clearly the conclusion which follows is not necessary. Suppose A necessarily belongs to all B, and let B be possible for all C. 40We shall have an imperfect syllogism to prove that A may belong to all C. That it is imperfect is clear from the proof: for it will be proved in the same manner as above.
If the premisses are affirmative, clearly the conclusion which follows is not necessary. Suppose A necessarily belongs to all B, and let B be possible for all C. 40We shall have an imperfect syllogism to prove that A may belong to all C. That it is imperfect is clear from the proof: for it will be proved in the same manner as above.
36a
1 ὑπάρχειν. ὅτι δ' ἀτελής, ἐκ τῆς ἀποδείξεως δῆλον· τὸν αὐτὸν
γὰρ τρόπον δειχθήσεται ὅνπερ κἀπὶ τῶν πρότερον. πάλιν
τὸ μὲν Α ἐνδεχέσθω παντὶ τῷ Β, τὸ δὲ Β παντὶ τῷ Γ ὑπαρχέτω
ἐξ ἀνάγκης. ἔσται δὴ συλλογισμὸς ὅτι τὸ Α παντὶ
5 τῷ Γ ἐνδέχεται ὑπάρχειν, ἀλλ' οὐχ ὅτι ὑπάρχει, καὶ τέλειος,
ἀλλ' οὐκ ἀτελής· εὐθὺς γὰρ ἐπιτελεῖται διὰ τῶν ἐξ
ἀρχῆς προτάσεων. Εἰ δὲ μὴ ὁμοιοσχήμονες αἱ προτάσεις,
ἔστω πρῶτον ἡ στερητικὴ ἀναγκαία, καὶ τὸ μὲν Α μηδενὶ
ἐνδεχέσθω τῷ Β, τὸ δὲ Β παντὶ τῷ Γ ἐνδεχέσθω.
10 ἀνάγκη δὴ τὸ Α μηδενὶ τῷ Γ ὑπάρχειν. κείσθω γὰρ
ὑπάρχειν ἢ παντὶ ἢ τινί· τῷ δὲ Β ὑπέκειτο μηδενὶ ἐνδέχεσθαι.
ἐπεὶ οὖν ἀντιστρέφει τὸ στερητικόν, οὐδὲ τὸ Β τῷ Α οὐδενὶ
ἐνδέχεται· τὸ δὲ Α τῷ Γ ἢ παντὶ ἢ τινὶ κεῖται ὑπάρχειν·
ὥστ' οὐδενὶ ἢ οὐ παντὶ τῷ Γ τὸ Β ἐνδέχοιτ' ἂν ὑπάρχειν·
15 ὑπέκειτο δὲ παντὶ ἐξ ἀρχῆς. φανερὸν δ' ὅτι καὶ τοῦ ἐνδέχεσθαι
μὴ ὑπάρχειν γίγνεται συλλογισμός, εἴπερ καὶ τοῦ μὴ
ὑπάρχειν. πάλιν ἔστω ἡ καταφατικὴ πρότασις ἀναγκαία,
καὶ τὸ μὲν Α ἐνδεχέσθω μηδενὶ τῷ Β ὑπάρχειν, τὸ δὲ Β
παντὶ τῷ Γ ὑπαρχέτω ἐξ ἀνάγκης. ὁ μὲν οὖν συλλογισμὸς
20 ἔσται τέλειος, ἀλλ' οὐ τοῦ μὴ ὑπάρχειν ἀλλὰ τοῦ ἐνδέχεσθαι
μὴ ὑπάρχειν· ἥ τε γὰρ πρότασις οὕτως ἐλήφθη ἡ ἀπὸ τοῦ
μείζονος ἄκρου, καὶ εἰς τὸ ἀδύνατον οὐκ ἔστιν ἀγαγεῖν· εἰ γὰρ
ὑποτεθείη τὸ Α τῷ Γ τινὶ ὑπάρχειν, κεῖται δὲ καὶ τῷ Β ἐνδέχεσθαι
μηδενὶ ὑπάρχειν, οὐδὲν συμβαίνει διὰ τούτων ἀδύνατον.
25 ἐὰν δὲ πρὸς τῷ ἐλάττονι ἄκρῳ τεθῇ τὸ στερητικόν,
ὅταν μὲν ἐνδέχεσθαι σημαίνῃ, συλλογισμὸς ἔσται διὰ τῆς
ἀντιστροφῆς, καθάπερ ἐν τοῖς πρότερον, ὅταν δὲ μὴ ἐνδέχεσθαι,
οὐκ ἔσται. οὐδ' ὅταν ἄμφω μὲν τεθῇ στερητικά, μὴ ᾖ δ'
ἐνδεχόμενον τὸ πρὸς τὸ ἔλαττον. ὅροι δ' οἱ αὐτοί, τοῦ μὲν
30 ὑπάρχειν λευκόν—ζῷον—χιών, τοῦ δὲ μὴ ὑπάρχειν λευκόν—
ζῷον—πίττα.
Τὸν αὐτὸν δὲ τρόπον ἕξει κἀπὶ τῶν ἐν μέρει συλλογισμῶν.
ὅταν μὲν γὰρ ᾖ τὸ στερητικὸν ἀναγκαῖον, καὶ τὸ συμπέρασμα ἔσται
τοῦ μὴ ὑπάρχειν. οἷον εἰ τὸ μὲν Α μηδενὶ τῷ Β ἐνδέχεται ὑπάρχειν,
35 τὸ δὲ Β τινὶ τῷ Γ ἐνδέχεται ὑπάρχειν, ἀνάγκη τὸ Α τινὶ
τῷ Γ μὴ ὑπάρχειν. εἰ γὰρ παντὶ ὑπάρχει, τῷ δὲ Β μηδενὶ
ἐνδέχεται, οὐδὲ τὸ Β οὐδενὶ τῷ Α ἐνδέχεται ὑπάρχειν. ὥστ' εἰ τὸ
Α παντὶ τῷ Γ ὑπάρχει, οὐδενὶ τῷ Γ τὸ Β ἐνδέχεται. ἀλλ' ὑπέκειτό
τινι ἐνδέχεσθαι. ὅταν δὲ τὸ ἐν μέρει καταφατικὸν ἀναγκαῖον
40 ᾖ, τὸ ἐν τῷ στερητικῷ συλλογισμῷ, οἷον τὸ Β Γ, ἢ τὸ καθόλου
1Again, let A be possible for all B, and let B necessarily belong to all C. We shall then have a syllogism to prove that 5A may belong to all C, not that A does belong to all C: and it is perfect, not imperfect: for it is completed directly through the original premisses.
But if the premisses are not similar in quality, suppose first that the negative premiss is necessary, and let necessarily A not be possible for any B, but let B be possible for all C. 10It is necessary then that A belongs to no C. For suppose A to belong to all C or to some C. Now we assumed that A is not possible for any B. Since then the negative proposition is convertible, B is not possible for any A. But A is supposed to belong to all C or to some C. Consequently B will not be possible for any C or for all C. 15But it was originally laid down that B is possible for all C. And it is clear that the possibility of belonging can be inferred, since the fact of not belonging is inferred. Again, let the affirmative premiss be necessary, and let A possibly not belong to any B, and let B necessarily belong to all C. 20The syllogism will be perfect, but it will establish a problematic negative, not an assertoric negative. For the major premiss was problematic, and further it is not possible to prove the assertoric conclusion per impossibile. For if it were supposed that A belongs to some C, and it is laid down that A possibly does not belong to any B, no impossible relation between B and C follows from these premisses. 25But if the minor premiss is negative, when it is problematic a syllogism is possible by conversion, as above; but when it is necessary no syllogism can be formed. Nor again when both premisses are negative, and the minor is necessary. The same terms as before serve both for the 30positive relation-white-animal-snow, and for the negative relation-white-animal-pitch.
The same relation will obtain in particular syllogisms. Whenever the negative proposition is necessary, the conclusion will be negative assertoric: e.g. if it is not possible that A should belong to any B, but 35B may belong to some of the Cs, it is necessary that A should not belong to some of the Cs. For if A belongs to all C, but cannot belong to any B, neither can B belong to any A. So if A belongs to all C, to none of the Cs can B belong. But it was laid down that B may belong to some C. But when 40the particular affirmative in the negative syllogism, e.g. BC the minor premiss, or the universal proposition in the affirmative syllogism, e.g. AB the major premiss, is necessary, there will not be an assertoric conclusion. The demonstration is the same as before.
But if the premisses are not similar in quality, suppose first that the negative premiss is necessary, and let necessarily A not be possible for any B, but let B be possible for all C. 10It is necessary then that A belongs to no C. For suppose A to belong to all C or to some C. Now we assumed that A is not possible for any B. Since then the negative proposition is convertible, B is not possible for any A. But A is supposed to belong to all C or to some C. Consequently B will not be possible for any C or for all C. 15But it was originally laid down that B is possible for all C. And it is clear that the possibility of belonging can be inferred, since the fact of not belonging is inferred. Again, let the affirmative premiss be necessary, and let A possibly not belong to any B, and let B necessarily belong to all C. 20The syllogism will be perfect, but it will establish a problematic negative, not an assertoric negative. For the major premiss was problematic, and further it is not possible to prove the assertoric conclusion per impossibile. For if it were supposed that A belongs to some C, and it is laid down that A possibly does not belong to any B, no impossible relation between B and C follows from these premisses. 25But if the minor premiss is negative, when it is problematic a syllogism is possible by conversion, as above; but when it is necessary no syllogism can be formed. Nor again when both premisses are negative, and the minor is necessary. The same terms as before serve both for the 30positive relation-white-animal-snow, and for the negative relation-white-animal-pitch.
The same relation will obtain in particular syllogisms. Whenever the negative proposition is necessary, the conclusion will be negative assertoric: e.g. if it is not possible that A should belong to any B, but 35B may belong to some of the Cs, it is necessary that A should not belong to some of the Cs. For if A belongs to all C, but cannot belong to any B, neither can B belong to any A. So if A belongs to all C, to none of the Cs can B belong. But it was laid down that B may belong to some C. But when 40the particular affirmative in the negative syllogism, e.g. BC the minor premiss, or the universal proposition in the affirmative syllogism, e.g. AB the major premiss, is necessary, there will not be an assertoric conclusion. The demonstration is the same as before.
36b
1 τὸ ἐν τῷ κατηγορικῷ, οἷον τὸ Α Β, οὐκ ἔσται τοῦ ὑπάρχειν
συλλογισμός. ἀπόδειξις δ' ἡ αὐτὴ ἣ καὶ ἐπὶ τῶν πρότερον.
ἐὰν δὲ τὸ μὲν καθόλου τεθῇ πρὸς τὸ ἔλαττον ἄκρον, ἢ καταφατικὸν
ἢ στερητικόν, ἐνδεχόμενον, τὸ δ' ἐν μέρει ἀναγκαῖον
5 [πρὸς τῷ μείζονι ἄκρῳ], οὐκ ἔσται συλλογισμός (ὅροι δὲ
τοῦ μὲν ὑπάρχειν ἐξ ἀνάγκης ζῷον—λευκόν—ἄνθρωπος, τοῦ δὲ
μὴ ἐνδέχεσθαι ζῷον—λευκόν—ἱμάτιον)· ὅταν δ' ἀναγκαῖον ᾖ
τὸ καθόλου, τὸ δ' ἐν μέρει ἐνδεχόμενον, στερητικοῦ μὲν ὄντος
τοῦ καθόλου τοῦ μὲν ὑπάρχειν ὅροι ζῷον—λευκόν—κόραξ, τοῦ
10 δὲ μὴ ὑπάρχειν ζῷον—λευκόν—πίττα, καταφατικοῦ δὲ τοῦ
μὲν ὑπάρχειν ζῷον—λευκόν—κύκνος, τοῦ δὲ μὴ ἐνδέχεσθαι
ζῷον—λευκόν—χιών. οὐδ' ὅταν ἀδιόριστοι ληφθῶσιν αἱ προτάσεις
ἢ ἀμφότεραι κατὰ μέρος, οὐδ' οὕτως ἔσται συλλογισμός.
ὅροι δὲ κοινοὶ τοῦ μὲν ὑπάρχειν ζῷον—λευκόν—ἄνθρωπος, τοῦ
15 δὲ μὴ ὑπάρχειν ζῷον—λευκόν—ἄψυχον. καὶ γὰρ τὸ ζῷον
τινὶ λευκῷ καὶ τὸ λευκὸν ἀψύχῳ τινὶ καὶ ἀναγκαῖον ὑπάρχειν
καὶ οὐκ ἐνδέχεται ὑπάρχειν. κἀπὶ τοῦ ἐνδέχεσθαι ὁμοίως,
ὥστε πρὸς ἅπαντα χρήσιμοι οἱ ὅροι.
Φανερὸν οὖν ἐκ τῶν εἰρημένων ὅτι ὁμοίως ἐχόντων τῶν
20 ὅρων ἔν τε τῷ ὑπάρχειν καὶ ἐν τοῖς ἀναγκαίοις γίνεταί τε καὶ
οὐ γίνεται συλλογισμός, πλὴν κατὰ μὲν τὸ ὑπάρχειν τιθεμένης
τῆς στερητικῆς προτάσεως τοῦ ἐνδέχεσθαι ἦν ὁ συλλογισμός,
κατὰ δὲ τὸ ἀναγκαῖον τῆς στερητικῆς καὶ τοῦ ἐνδέχεσθαι
καὶ τοῦ μὴ ὑπάρχειν. [δῆλον δὲ καὶ ὅτι πάντες ἀτελεῖς οἱ συλλογισμοὶ
25 καὶ ὅτι τελειοῦνται διὰ τῶν προειρημένων σχημάτων.]
1But if the minor premiss is universal, and problematic, whether affirmative or negative, 5and the major premiss is particular and necessary, there cannot be a syllogism. Premisses of this kind are possible both where the relation is positive and necessary, e.g. animal-white-man, and where it is necessary and negative, e.g. animal-white-garment. But when the universal is necessary, the particular problematic, if the universal is negative we may take the terms animal-white-raven to illustrate the positive relation, or animal-white-pitch to illustrate 10the negative; and if the universal is affirmative we may take the terms animal-white-swan to illustrate the positive relation, and animal-white-snow to illustrate the negative and necessary relation. Nor again is a syllogism possible when the premisses are indefinite, or both particular. Terms applicable in either case to illustrate the positive relation are animal-white-man: 15to illustrate the negative, animal-white-inanimate. For the relation of animal to some white, and of white to some inanimate, is both necessary and positive and necessary and negative. Similarly if the relation is problematic: so the terms may be used for all cases.
Clearly then from what has been said 20a syllogism results or not from similar relations of the terms whether we are dealing with simple existence or necessity, with this exception, that if the negative premiss is assertoric the conclusion is problematic, but if the negative premiss is necessary the conclusion is both problematic and negative assertoric. [It is clear also that all the syllogisms are imperfect 25and are perfected by means of the figures above mentioned.]
Clearly then from what has been said 20a syllogism results or not from similar relations of the terms whether we are dealing with simple existence or necessity, with this exception, that if the negative premiss is assertoric the conclusion is problematic, but if the negative premiss is necessary the conclusion is both problematic and negative assertoric. [It is clear also that all the syllogisms are imperfect 25and are perfected by means of the figures above mentioned.]
Book 1,Chapter 17 (36b26–37b18)
Ἐν δὲ τῷ δευτέρῳ σχήματι ὅταν μὲν ἐνδέχεσθαι λαμβάνωσιν
ἀμφότεραι αἱ προτάσεις, οὐδεὶς ἔσται συλλογισμός,
οὔτε κατηγορικῶν οὔτε στερητικῶν τιθεμένων, οὔτε καθόλου οὔτε
κατὰ μέρος· ὅταν δὲ ἡ μὲν ὑπάρχειν ἡ δ' ἐνδέχεσθαι σημαίνῃ,
30 τῆς μὲν καταφατικῆς ὑπάρχειν σημαινούσης οὐδέποτ' ἔσται,
τῆς δὲ στερητικῆς τῆς καθόλου ἀεί. τὸν αὐτὸν δὲ τρόπον καὶ
ὅταν ἡ μὲν ἐξ ἀνάγκης ἡ δ' ἐνδέχεσθαι λαμβάνηται τῶν
προτάσεων. δεῖ δὲ καὶ ἐν τούτοις λαμβάνειν τὸ ἐν τοῖς συμπεράσμασιν
ἐνδεχόμενον ὥσπερ ἐν τοῖς πρότερον.
35 Πρῶτον οὖν δεικτέον ὅτι οὐκ ἀντιστρέφει τὸ ἐν τῷ ἐνδέχεσθαι
στερητικόν, οἷον εἰ τὸ Α ἐνδέχεται μηδενὶ τῷ Β, οὐκ ἀνάγκη καὶ
τὸ Β ἐνδέχεσθαι μηδενὶ τῷ Α. κείσθω γὰρ τοῦτο, καὶ ἐνδεχέσθω
τὸ Β μηδενὶ τῷ Α ὑπάρχειν. οὐκοῦν ἐπεὶ ἀντιστρέφουσιν αἱ ἐν
τῷ ἐνδέχεσθαι καταφάσεις ταῖς ἀποφάσεσι, καὶ αἱ ἐναντίαι
40 καὶ αἱ ἀντικείμεναι, τὸ δὲ Β τῷ Α ἐνδέχεται μηδενὶ ὑπάρχειν,
26In the second figure whenever both premisses are problematic, no syllogism is possible, whether the premisses are affirmative or negative, universal or particular. But when one premiss is assertoric, the other problematic, 30if the affirmative is assertoric no syllogism is possible, but if the universal negative is assertoric a conclusion can always be drawn. Similarly when one premiss is necessary, the other problematic. Here also we must understand the term 'possible' in the conclusion, in the same sense as before.
35First we must point out that the negative problematic proposition is not convertible, e.g. if A may belong to no B, it does not follow that B may belong to no A. For suppose it to follow and assume that B may belong to no A. Since then problematic affirmations are convertible with negations, 40whether they are contraries or contradictories, and since B may belong to no A, it is clear that B may belong to all A. But this is false: for if all this can be that, it does not follow that all that can be this: consequently the negative proposition is not convertible.
35First we must point out that the negative problematic proposition is not convertible, e.g. if A may belong to no B, it does not follow that B may belong to no A. For suppose it to follow and assume that B may belong to no A. Since then problematic affirmations are convertible with negations, 40whether they are contraries or contradictories, and since B may belong to no A, it is clear that B may belong to all A. But this is false: for if all this can be that, it does not follow that all that can be this: consequently the negative proposition is not convertible.
37a
1 φανερὸν ὅτι καὶ παντὶ ἂν ἐνδέχοιτο τῷ Α ὑπάρχειν.
τοῦτο δὲ ψεῦδος· οὐ γὰρ εἰ τόδε τῷδε παντὶ ἐνδέχεται, καὶ
τόδε τῷδε ἀναγκαῖον· ὥστ' οὐκ ἀντιστρέφει τὸ στερητικόν.
ἔτι δ' οὐδὲν κωλύει τὸ μὲν Α τῷ Β ἐνδέχεσθαι μηδενί, τὸ δὲ
5 Β τινὶ τῶν Α ἐξ ἀνάγκης μὴ ὑπάρχειν, οἷον τὸ μὲν λευκὸν
παντὶ ἀνθρώπῳ ἐνδέχεται μὴ ὑπάρχειν (καὶ γὰρ ὑπάρχειν),
ἄνθρωπον δ' οὐκ ἀληθὲς εἰπεῖν ὡς ἐνδέχεται μηδενὶ λευκῷ·
πολλοῖς γὰρ ἐξ ἀνάγκης οὐχ ὑπάρχει, τὸ δ' ἀναγκαῖον
οὐκ ἦν ἐνδεχόμενον. Ἀλλὰ μὴν οὐδ' ἐκ τοῦ ἀδυνάτου δειχθήσεται
10 ἀντιστρέφον, οἷον εἴ τις ἀξιώσειεν, ἐπεὶ ψεῦδος τὸ ἐνδέχεσθαι
τὸ Β τῷ Α μηδενὶ ὑπάρχειν, ἀληθὲς τὸ μὴ ἐνδέχεσθαι
μηδενί (φάσις γὰρ καὶ ἀπόφασις), εἰ δὲ τοῦτ', ἀληθὲς
ἐξ ἀνάγκης τινὶ τῷ Α ὑπάρχειν· ὥστε καὶ τὸ Α τινὶ
τῷ Β· τοῦτο δ' ἀδύνατον. οὐ γὰρ εἰ μὴ ἐνδέχεται μηδενὶ
15 τὸ Β τῷ Α, ἀνάγκη τινὶ ὑπάρχειν. τὸ γὰρ μὴ ἐνδέχεσθαι
μηδενὶ διχῶς λέγεται, τὸ μὲν εἰ ἐξ ἀνάγκης τινὶ ὑπάρχει,
τὸ δ' εἰ ἐξ ἀνάγκης τινὶ μὴ ὑπάρχει· τὸ γὰρ ἐξ ἀνάγκης
τινὶ τῶν Α μὴ ὑπάρχον οὐκ ἀληθὲς εἰπεῖν ὡς παντὶ ἐνδέχεται
μὴ ὑπάρχειν, ὥσπερ οὐδὲ τὸ τινὶ ὑπάρχον ἐξ ἀνάγκης ὅτι
20 παντὶ ἐνδέχεται ὑπάρχειν. εἰ οὖν τις ἀξιοίη, ἐπεὶ οὐκ ἐνδέχεται
τὸ Γ τῷ Δ παντὶ ὑπάρχειν, ἐξ ἀνάγκης τινὶ μὴ ὑπάρχειν
αὐτό, ψεῦδος ἂν λαμβάνοι· παντὶ γὰρ ὑπάρχει, ἀλλ' ὅτι
ἐνίοις ἐξ ἀνάγκης ὑπάρχει, διὰ τοῦτό φαμεν οὐ παντὶ ἐνδέχεσθαι.
ὥστε τῷ ἐνδέχεσθαι παντὶ ὑπάρχειν τό τ' ἐξ ἀνάγκης
25 τινὶ ὑπάρχειν ἀντίκειται καὶ τὸ ἐξ ἀνάγκης τινὶ μὴ ὑπάρχειν.
ὁμοίως δὲ καὶ τῷ ἐνδέχεσθαι μηδενί. δῆλον οὖν ὅτι πρὸς
τὸ οὕτως ἐνδεχόμενον καὶ μὴ ἐνδεχόμενον ὡς ἐν ἀρχῇ διωρίσαμεν
οὐ τὸ ἐξ ἀνάγκης τινὶ ὑπάρχειν ἀλλὰ τὸ ἐξ ἀνάγκης
τινὶ μὴ ὑπάρχειν ληπτέον. τούτου δὲ ληφθέντος οὐδὲν συμβαίνει
30 ἀδύνατον, ὥστ' οὐ γίνεται συλλογισμός. φανερὸν οὖν ἐκ τῶν εἰρημένων
ὅτι οὐκ ἀντιστρέφει τὸ στερητικόν.
Τούτου δὲ δειχθέντος κείσθω τὸ Α τῷ μὲν Β ἐνδέχεσθαι
μηδενί, τῷ δὲ Γ παντί. διὰ μὲν οὖν τῆς ἀντιστροφῆς οὐκ ἔσται
συλλογισμός· εἴρηται γὰρ ὅτι οὐκ ἀντιστρέφει ἡ τοιαύτη πρότασις.
35 ἀλλ' οὐδὲ διὰ τοῦ ἀδυνάτου· τεθέντος γὰρ τοῦ Β <μὴ> παντὶ
τῷ Γ ἐνδέχεσθαι <μὴ> ὑπάρχειν οὐδὲν συμβαίνει ψεῦδος· ἐνδέχοιτο
γὰρ ἂν τὸ Α τῷ Γ καὶ παντὶ καὶ μηδενὶ ὑπάρχειν.
ὅλως δ' εἰ ἔστι συλλογισμός, δῆλον ὅτι τοῦ ἐνδέχεσθαι ἂν
εἴη διὰ τὸ μηδετέραν τῶν προτάσεων εἰλῆφθαι ἐν τῷ ὑπάρχειν,
40 καὶ οὗτος ἢ καταφατικὸς ἢ στερητικός· οὐδετέρως δ' ἐγχωρεῖ.
1Further, these propositions are not incompatible, 'A may belong to no B', 5'B necessarily does not belong to some of the As'; e.g. it is possible that no man should be white (for it is also possible that every man should be white), but it is not true to say that it is possible that no white thing should be a man: for many white things are necessarily not men, and the necessary (as we saw) other than the possible.
Moreover it is not possible to prove the convertibility of these propositions by a reductio ad absurdum, i.e. 10by claiming assent to the following argument: 'since it is false that B may belong to no A, it is true that it cannot belong to no A, for the one statement is the contradictory of the other. But if this is so, 15it is true that B necessarily belongs to some of the As: consequently A necessarily belongs to some of the Bs. But this is impossible.' The argument cannot be admitted, for it does not follow that some A is necessarily B, if it is not possible that no A should be B. For the latter expression is used in two senses, one if A some is necessarily B, another if some A is necessarily not B. For it is not true to say that that which necessarily does not belong to some of the As may possibly not belong to any A, just as it is not true to say that what necessarily belongs to some A 20may possibly belong to all A. If any one then should claim that because it is not possible for C to belong to all D, it necessarily does not belong to some D, he would make a false assumption: for it does belong to all D, but because in some cases it belongs necessarily, therefore we say that it is not possible for it to belong to all. Hence both the propositions 'A necessarily belongs to some B' and 25'A necessarily does not belong to some B' are opposed to the proposition 'A belongs to all B'. Similarly also they are opposed to the proposition 'A may belong to no B'. It is clear then that in relation to what is possible and not possible, in the sense originally defined, we must assume, not that A necessarily belongs to some B, but that A necessarily does not belong to some B. But if this is assumed, 30no absurdity results: consequently no syllogism. It is clear from what has been said that the negative proposition is not convertible.
This being proved, suppose it possible that A may belong to no B and to all C. By means of conversion no syllogism will result: for the major premiss, as has been said, is not convertible. 35Nor can a proof be obtained by a reductio ad absurdum: for if it is assumed that B can belong to all C, no false consequence results: for A may belong both to all C and to no C.
Moreover it is not possible to prove the convertibility of these propositions by a reductio ad absurdum, i.e. 10by claiming assent to the following argument: 'since it is false that B may belong to no A, it is true that it cannot belong to no A, for the one statement is the contradictory of the other. But if this is so, 15it is true that B necessarily belongs to some of the As: consequently A necessarily belongs to some of the Bs. But this is impossible.' The argument cannot be admitted, for it does not follow that some A is necessarily B, if it is not possible that no A should be B. For the latter expression is used in two senses, one if A some is necessarily B, another if some A is necessarily not B. For it is not true to say that that which necessarily does not belong to some of the As may possibly not belong to any A, just as it is not true to say that what necessarily belongs to some A 20may possibly belong to all A. If any one then should claim that because it is not possible for C to belong to all D, it necessarily does not belong to some D, he would make a false assumption: for it does belong to all D, but because in some cases it belongs necessarily, therefore we say that it is not possible for it to belong to all. Hence both the propositions 'A necessarily belongs to some B' and 25'A necessarily does not belong to some B' are opposed to the proposition 'A belongs to all B'. Similarly also they are opposed to the proposition 'A may belong to no B'. It is clear then that in relation to what is possible and not possible, in the sense originally defined, we must assume, not that A necessarily belongs to some B, but that A necessarily does not belong to some B. But if this is assumed, 30no absurdity results: consequently no syllogism. It is clear from what has been said that the negative proposition is not convertible.
This being proved, suppose it possible that A may belong to no B and to all C. By means of conversion no syllogism will result: for the major premiss, as has been said, is not convertible. 35Nor can a proof be obtained by a reductio ad absurdum: for if it is assumed that B can belong to all C, no false consequence results: for A may belong both to all C and to no C.
37b
1 καταφατικοῦ μὲν γὰρ τεθέντος δειχθήσεται διὰ τῶν
ὅρων ὅτι οὐκ ἐνδέχεται ὑπάρχειν, στερητικοῦ δέ, ὅτι τὸ συμπέρασμα
οὐκ ἐνδεχόμενον ἀλλ' ἀναγκαῖόν ἐστιν. ἔστω γὰρ τὸ
μὲν Α λευκόν, τὸ δὲ Β ἄνθρωπος, ἐφ' ᾧ δὲ Γ ἵππος. τὸ
5 δὴ Α, τὸ λευκόν, ἐνδέχεται τῷ μὲν παντὶ τῷ δὲ μηδενὶ
ὑπάρχειν. ἀλλὰ τὸ Β τῷ Γ οὔτε ὑπάρχειν ἐνδέχεται οὔτε μὴ
ὑπάρχειν. ὅτι μὲν οὖν ὑπάρχειν οὐκ ἐγχωρεῖ, φανερόν· οὐδεὶς
γὰρ ἵππος ἄνθρωπος. ἀλλ' οὐδ' ἐνδέχεσθαι μὴ ὑπάρχειν·
ἀνάγκη γὰρ μηδένα ἵππον ἄνθρωπον εἶναι, τὸ δ' ἀναγκαῖον
10 οὐκ ἦν ἐνδεχόμενον. οὐκ ἄρα γίνεται συλλογισμός. ὁμοίως
δὲ δειχθήσεται καὶ ἂν ἀνάπαλιν τεθῇ τὸ στερητικόν, κἂν ἀμφότεραι
καταφατικαὶ ληφθῶσιν ἢ στερητικαί (διὰ γὰρ
τῶν αὐτῶν ὅρων ἔσται ἡ ἀπόδειξις)· καὶ ὅταν ἡ μὲν καθόλου
ἡ δ' ἐν μέρει, ἢ ἀμφότεραι κατὰ μέρος ἢ ἀδιόριστοι, ἢ ὁσαχῶς
15 ἄλλως ἐνδέχεται μεταλαβεῖν τὰς προτάσεις· ἀεὶ γὰρ
ἔσται διὰ τῶν αὐτῶν ὅρων ἡ ἀπόδειξις. φανερὸν οὖν ὅτι ἀμφοτέρων
τῶν προτάσεων κατὰ τὸ ἐνδέχεσθαι τιθεμένων οὐδεὶς
γίνεται συλλογισμός.
1In general, if there is a syllogism, it is clear that its conclusion will be problematic because neither of the premisses is assertoric; and this must be either affirmative or negative. But neither is possible. Suppose the conclusion is affirmative: it will be proved by an example that the predicate cannot belong to the subject. Suppose the conclusion is negative: it will be proved that it is not problematic but necessary. Let A be white, B man, C horse. 5It is possible then for A to belong to all of the one and to none of the other. But it is not possible for B to belong nor not to belong to C. That it is not possible for it to belong, is clear. For no horse is a man. Neither is it possible for it not to belong. For it is necessary that no horse should be a man, but the necessary we found to be different from the possible. 10No syllogism then results. A similar proof can be given if the major premiss is negative, the minor affirmative, or if both are affirmative or negative. The demonstration can be made by means of the same terms. And whenever one premiss is universal, the other particular, or both are particular or indefinite, 15or in whatever other way the premisses can be altered, the proof will always proceed through the same terms. Clearly then, if both the premisses are problematic, no syllogism results.
Book 1,Chapter 18 (37b19–38a12)
Εἰ δ' ἡ μὲν ὑπάρχειν ἡ δ' ἐνδέχεσθαι σημαίνει, τῆς
20 μὲν κατηγορικῆς ὑπάρχειν τεθείσης τῆς δὲ στερητικῆς ἐνδέχεσθαι
οὐδέποτ' ἔσται συλλογισμός, οὔτε καθόλου τῶν ὅρων
οὔτ' ἐν μέρει λαμβανομένων (ἀπόδειξις δ' ἡ αὐτὴ καὶ διὰ
τῶν αὐτῶν ὅρων)· ὅταν δ' ἡ μὲν καταφατικὴ ἐνδέχεσθαι ἡ
δὲ στερητικὴ ὑπάρχειν, ἔσται συλλογισμός. εἰλήφθω γὰρ τὸ
25 Α τῷ μὲν Β μηδενὶ ὑπάρχειν, τῷ δὲ Γ παντὶ ἐνδέχεσθαι.
ἀντιστραφέντος οὖν τοῦ στερητικοῦ τὸ Β τῷ Α οὐδενὶ ὑπάρξει·
τὸ δὲ Α παντὶ τῷ Γ ἐνεδέχετο· γίνεται δὴ συλλογισμὸς
ὅτι ἐνδέχεται τὸ Β μηδενὶ τῷ Γ διὰ τοῦ πρώτου σχήματος.
ὁμοίως δὲ καὶ εἰ πρὸς τῷ Γ τεθείη τὸ στερητικόν. ἐὰν δ' ἀμφότεραι
30 μὲν ὦσι στερητικαί, σημαίνῃ δ' ἡ μὲν μὴ ὑπάρχειν
ἡ δ' ἐνδέχεσθαι, δι' αὐτῶν μὲν τῶν εἰλημμένων
οὐδὲν συμβαίνει ἀναγκαῖον, ἀντιστραφείσης δὲ τῆς κατὰ τὸ
ἐνδέχεσθαι προτάσεως γίγνεται συλλογισμὸς ὅτι τὸ Β τῷ
Γ ἐνδέχεται μηδενὶ ὑπάρχειν, καθάπερ ἐν τοῖς πρότερον·
35 ἔσται γὰρ πάλιν τὸ πρῶτον σχῆμα. ἐὰν δ' ἀμφότεραι τεθῶσι
κατηγορικαί, οὐκ ἔσται συλλογισμός. ὅροι τοῦ μὲν ὑπάρχειν
ὑγίεια—ζῷον—ἄνθρωπος, τοῦ δὲ μὴ ὑπάρχειν ὑγίεια—
ἵππος—ἄνθρωπος.
Τὸν αὐτὸν δὲ τρόπον ἕξει κἀπὶ τῶν ἐν μέρει συλλογισμῶν.
40 ὅταν μὲν γὰρ ᾖ τὸ καταφατικὸν ὑπάρχον, εἴτε καθόλου
19But if one premiss is assertoric, the other problematic, if the affirmative is assertoric and the negative problematic no syllogism will be possible, whether the premisses are universal or particular. The proof is the same as above, and by means of the same terms. But when the affirmative premiss is problematic, and the negative assertoric, we shall have a syllogism. 25Suppose A belongs to no B, but can belong to all C. If the negative proposition is converted, B will belong to no A. But ex hypothesi can belong to all C: so a syllogism is made, proving by means of the first figure that B may belong to no C. Similarly also if the minor premiss is negative. 30But if both premisses are negative, one being assertoric, the other problematic, nothing follows necessarily from these premisses as they stand, but if the problematic premiss is converted into its complementary affirmative a syllogism is formed to prove that B may belong to no C, as before: 35for we shall again have the first figure. But if both premisses are affirmative, no syllogism will be possible. This arrangement of terms is possible both when the relation is positive, e.g. health, animal, man, and when it is negative, e.g. health, horse, man.
40The same will hold good if the syllogisms are particular.
40The same will hold good if the syllogisms are particular.
38a
1 εἴτ' ἐν μέρει ληφθέν, οὐδεὶς ἔσται συλλογισμός (τοῦτο
δ' ὁμοίως καὶ διὰ τῶν αὐτῶν ὅρων δείκνυται τοῖς πρότερον),
ὅταν δὲ τὸ στερητικόν, ἔσται διὰ τῆς ἀντιστροφῆς, καθάπερ
ἐν τοῖς πρότερον. πάλιν ἐὰν ἄμφω μὲν τὰ διαστήματα στερητικὰ
5 ληφθῇ, καθόλου δὲ τὸ μὴ ὑπάρχειν, ἐξ αὐτῶν μὲν
τῶν προτάσεων οὐκ ἔσται τὸ ἀναγκαῖον, ἀντιστραφέντος δὲ τοῦ
ἐνδέχεσθαι καθάπερ ἐν τοῖς πρότερον ἔσται συλλογισμός.
ἐὰν δὲ ὑπάρχον μὲν ᾖ τὸ στερητικόν, ἐν μέρει δὲ ληφθῇ, οὐκ
ἔσται συλλογισμός, οὔτε καταφατικῆς οὔτε στερητικῆς οὔσης
10 τῆς ἑτέρας προτάσεως. οὐδ' ὅταν ἀμφότεραι ληφθῶσιν ἀδιόριστοι—ἢ
καταφατικαὶ ἢ ἀποφατικαί—ἢ κατὰ μέρος. ἀπόδειξις
δ' ἡ αὐτὴ καὶ διὰ τῶν αὐτῶν ὅρων.
1Whenever the affirmative proposition is assertoric, whether universal or particular, no syllogism is possible (this is proved similarly and by the same examples as above), but when the negative proposition is assertoric, a conclusion can be drawn by means of conversion, as before. Again if both the relations are negative, 5and the assertoric proposition is universal, although no conclusion follows from the actual premisses, a syllogism can be obtained by converting the problematic premiss into its complementary affirmative as before. But if the negative proposition is assertoric, but particular, no syllogism is possible, whether the other premiss is affirmative or negative. 10Nor can a conclusion be drawn when both premisses are indefinite, whether affirmative or negative, or particular. The proof is the same and by the same terms.
Book 1,Chapter 19 (38a13–39a3)
Ἐὰν δ' ἡ μὲν ἐξ ἀνάγκης ἡ δ' ἐνδέχεσθαι σημαίνῃ
τῶν προτάσεων, τῆς μὲν στερητικῆς ἀναγκαίας οὔσης ἔσται
15 συλλογισμός, οὐ μόνον ὅτι ἐνδέχεται μὴ ὑπάρχειν, ἀλλὰ
καὶ ὅτι οὐχ ὑπάρχει, τῆς δὲ καταφατικῆς οὐκ ἔσται. κείσθω
γὰρ τὸ Α τῷ μὲν Β ἐξ ἀνάγκης μηδενὶ ὑπάρχειν, τῷ δὲ
Γ παντὶ ἐνδέχεσθαι. ἀντιστραφείσης οὖν τῆς στερητικῆς οὐδὲ
τὸ Β τῷ Α οὐδενὶ ὑπάρξει· τὸ δὲ Α παντὶ τῷ Γ ἐνεδέχετο·
20 γίνεται δὴ πάλιν διὰ τοῦ πρώτου σχήματος ὁ συλλογισμὸς
ὅτι τὸ Β τῷ Γ ἐνδέχεται μηδενὶ ὑπάρχειν. ἅμα δὲ δῆλον
ὅτι οὐδ' ὑπάρξει τὸ Β οὐδενὶ τῷ Γ. κείσθω γὰρ ὑπάρχειν·
οὐκοῦν εἰ τὸ Α τῷ Β μηδενὶ ἐνδέχεται, τὸ δὲ Β ὑπάρχει
τινὶ τῷ Γ, τὸ Α τῷ Γ τινὶ οὐκ ἐνδέχεται· ἀλλὰ παντὶ ὑπέκειτο
25 ἐνδέχεσθαι. τὸν αὐτὸν δὲ τρόπον δειχθήσεται καὶ εἰ
πρὸς τῷ Γ τεθείη τὸ στερητικόν. Πάλιν ἔστω τὸ κατηγορικὸν
ἀναγκαῖον, θάτερον δ' ἐνδεχόμενον, καὶ τὸ Α τῷ μὲν Β ἐνδεχέσθω
μηδενί, τῷ δὲ Γ παντὶ ὑπαρχέτω ἐξ ἀνάγκης. οὕτως
οὖν ἐχόντων τῶν ὅρων οὐδεὶς ἔσται συλλογισμός. συμβαίνει
30 γὰρ τὸ Β τῷ Γ ἐξ ἀνάγκης μὴ ὑπάρχειν. ἔστω γὰρ
τὸ μὲν Α λευκόν, ἐφ' ᾧ δὲ τὸ Β ἄνθρωπος, ἐφ' ᾧ δὲ
τὸ Γ κύκνος. τὸ δὴ λευκὸν κύκνῳ μὲν ἐξ ἀνάγκης ὑπάρχει,
ἀνθρώπῳ δ' ἐνδέχεται μηδενί· καὶ ἄνθρωπος οὐδενὶ
κύκνῳ ἐξ ἀνάγκης. ὅτι μὲν οὖν τοῦ ἐνδέχεσθαι οὐκ ἔστι
35 συλλογισμός, φανερόν· τὸ γὰρ ἐξ ἀνάγκης οὐκ ἦν ἐνδεχόμενον.
ἀλλὰ μὴν οὐδὲ τοῦ ἀναγκαίου· τὸ γὰρ ἀναγκαῖον
ἢ ἐξ ἀμφοτέρων ἀναγκαίων ἢ ἐκ τῆς στερητικῆς συνέβαινεν.
ἔτι δὲ καὶ ἐγχωρεῖ τούτων κειμένων τὸ Β τῷ Γ ὑπάρχειν·
οὐδὲν γὰρ κωλύει τὸ μὲν Γ ὑπὸ τὸ Β εἶναι, τὸ δὲ
40 Α τῷ μὲν Β παντὶ ἐνδέχεσθαι, τῷ δὲ Γ ἐξ ἀνάγκης
ὑπάρχειν, οἷον εἰ τὸ μὲν Γ εἴη ἐγρηγορός, τὸ δὲ Β ζῷον,
τὸ δ' ἐφ' ᾧ τὸ Α κίνησις. τῷ μὲν γὰρ ἐγρηγορότι ἐξ ἀνάγκης
13If one of the premisses is necessary, the other problematic, then if the negative is necessary 15a syllogistic conclusion can be drawn, not merely a negative problematic but also a negative assertoric conclusion; but if the affirmative premiss is necessary, no conclusion is possible. Suppose that A necessarily belongs to no B, but may belong to all C. If the negative premiss is converted B will belong to no A: but A ex hypothesi is capable of belonging to all C: 20so once more a conclusion is drawn by the first figure that B may belong to no C. But at the same time it is clear that B will not belong to any C. For assume that it does: then if A cannot belong to any B, and B belongs to some of the Cs, A cannot belong to some of the Cs: but ex hypothesi it may belong to all. 25A similar proof can be given if the minor premiss is negative. Again let the affirmative proposition be necessary, and the other problematic; i.e. suppose that A may belong to no B, but necessarily belongs to all C. When the terms are arranged in this way, no syllogism is possible. For (1) it sometimes turns out 30that B necessarily does not belong to C. Let A be white, B man, C swan. White then necessarily belongs to swan, but may belong to no man; and man necessarily belongs to no swan; Clearly then we cannot draw a problematic conclusion; 35for that which is necessary is admittedly distinct from that which is possible. (2) Nor again can we draw a necessary conclusion: for that presupposes that both premisses are necessary, or at any rate the negative premiss. (3) Further it is possible also, when the terms are so arranged, that B should belong to C: for nothing prevents C falling under B, 40A being possible for all B, and necessarily belonging to C; e.g. if C stands for 'awake', B for 'animal', A for 'motion'. For motion necessarily belongs to what is awake, and is possible for every animal: and everything that is awake is animal.
38b
1 κίνησις, ζῴῳ δὲ παντὶ ἐνδέχεται· καὶ πᾶν τὸ ἐγρηγορὸς
ζῷον. φανερὸν οὖν ὅτι οὐδὲ τοῦ μὴ ὑπάρχειν, εἴπερ
οὕτως ἐχόντων ἀνάγκη ὑπάρχειν. οὐδὲ δὴ τῶν ἀντικειμένων
καταφάσεων, ὥστ' οὐδεὶς ἔσται συλλογισμός. ὁμοίως
5 δὲ δειχθήσεται καὶ ἀνάπαλιν τεθείσης τῆς καταφατικῆς.
Ἐὰν δ' ὁμοιοσχήμονες ὦσιν αἱ προτάσεις, στερητικῶν μὲν
οὐσῶν ἀεὶ γίνεται συλλογισμὸς ἀντιστραφείσης τῆς κατὰ
τὸ ἐνδέχεσθαι προτάσεως καθάπερ ἐν τοῖς πρότερον. εἰλήφθω
γὰρ τὸ Α τῷ μὲν Β ἐξ ἀνάγκης μὴ ὑπάρχειν, τῷ
10 δὲ Γ ἐνδέχεσθαι μὴ ὑπάρχειν· ἀντιστραφεισῶν οὖν τῶν προτάσεων
τὸ μὲν Β τῷ Α οὐδενὶ ὑπάρχει, τὸ δὲ Α παντὶ
τῷ Γ ἐνδέχεται· γίνεται δὴ τὸ πρῶτον σχῆμα. κἂν εἰ
πρὸς τῷ Γ τεθείη τὸ στερητικόν, ὡσαύτως. ἐὰν δὲ κατηγορικαὶ
τεθῶσιν, οὐκ ἔσται συλλογισμός. τοῦ μὲν γὰρ μὴ
15 ὑπάρχειν ἢ τοῦ ἐξ ἀνάγκης μὴ ὑπάρχειν φανερὸν ὅτι οὐκ
ἔσται διὰ τὸ μὴ εἰλῆφθαι στερητικὴν πρότασιν μήτ' ἐν τῷ
ὑπάρχειν μήτ' ἐν τῷ ἐξ ἀνάγκης ὑπάρχειν. ἀλλὰ μὴν
οὐδὲ τοῦ ἐνδέχεσθαι μὴ ὑπάρχειν· ἐξ ἀνάγκης γὰρ οὕτως
ἐχόντων τὸ Β τῷ Γ οὐχ ὑπάρξει, οἷον εἰ τὸ μὲν Α τεθείη
20 λευκόν, ἐφ' ᾧ δὲ τὸ Β κύκνος, τὸ δὲ Γ ἄνθρωπος.
οὐδέ γε τῶν ἀντικειμένων καταφάσεων, ἐπεὶ δέδεικται τὸ
Β τῷ Γ ἐξ ἀνάγκης οὐχ ὑπάρχον. οὐκ ἄρα γίνεται συλλογισμὸς
ὅλως.
Ὁμοίως δ' ἕξει κἀπὶ τῶν ἐν μέρει συλλογισμῶν·
25 ὅταν μὲν γὰρ ᾖ τὸ στερητικὸν καθόλου τε καὶ ἀναγκαῖον,
ἀεὶ συλλογισμὸς ἔσται καὶ τοῦ ἐνδέχεσθαι καὶ τοῦ μὴ
ὑπάρχειν (ἀπόδειξις δὲ διὰ τῆς ἀντιστροφῆς), ὅταν δὲ τὸ
καταφατικόν, οὐδέποτε· τὸν αὐτὸν γὰρ τρόπον δειχθήσεται
ὃν καὶ ἐν τοῖς καθόλου, καὶ διὰ τῶν αὐτῶν ὅρων. οὐδ' ὅταν
30 ἀμφότεραι ληφθῶσι καταφατικαί· καὶ γὰρ τούτου ἡ αὐτὴ
ἀπόδειξις ἣ καὶ πρότερον. ὅταν δὲ ἀμφότεραι μὲν στερητικαί,
καθόλου δὲ καὶ ἀναγκαία ἡ τὸ μὴ ὑπάρχειν σημαίνουσα,
δι' αὐτῶν μὲν τῶν εἰλημμένων οὐκ ἔσται τὸ ἀναγκαῖον,
ἀντιστραφείσης δὲ τῆς κατὰ τὸ ἐνδέχεσθαι προτάσεως
35 ἔσται συλλογισμός, καθάπερ ἐν τοῖς πρότερον. ἐὰν
δ' ἀμφότεραι ἀδιόριστοι ἢ ἐν μέρει τεθῶσιν, οὐκ ἔσται συλλογισμός.
ἀπόδειξις δ' ἡ αὐτὴ καὶ διὰ τῶν αὐτῶν ὅρων.
Φανερὸν οὖν ἐκ τῶν εἰρημένων ὅτι τῆς μὲν στερητικῆς
τῆς καθόλου τιθεμένης ἀναγκαίας ἀεὶ γίνεται συλλογισμὸς
40 οὐ μόνον τοῦ ἐνδέχεσθαι μὴ ὑπάρχειν, ἀλλὰ καὶ
τοῦ μὴ ὑπάρχειν, τῆς δὲ καταφατικῆς οὐδέποτε. καὶ ὅτι
τὸν αὐτὸν τρόπον ἐχόντων ἔν τε τοῖς ἀναγκαίοις καὶ ἐν τοῖς
1Clearly then the conclusion cannot be the negative assertion, if the relation must be positive when the terms are related as above. Nor can the opposite affirmations be established: consequently no syllogism is possible. 5A similar proof is possible if the major premiss is affirmative.
But if the premisses are similar in quality, when they are negative a syllogism can always be formed by converting the problematic premiss into its complementary affirmative as before. Suppose A necessarily does not belong to B, 10and possibly may not belong to C: if the premisses are converted B belongs to no A, and A may possibly belong to all C: thus we have the first figure. Similarly if the minor premiss is negative. But if the premisses are affirmative there cannot be a syllogism. Clearly the conclusion cannot be 15a negative assertoric or a negative necessary proposition because no negative premiss has been laid down either in the assertoric or in the necessary mode. Nor can the conclusion be a problematic negative proposition. For if the terms are so related, there are cases in which B necessarily will not belong to C; e.g. suppose 20that A is white, B swan, C man. Nor can the opposite affirmations be established, since we have shown a case in which B necessarily does not belong to C. A syllogism then is not possible at all.
Similar relations will obtain in particular syllogisms. 25For whenever the negative proposition is universal and necessary, a syllogism will always be possible to prove both a problematic and a negative assertoric proposition (the proof proceeds by conversion); but when the affirmative proposition is universal and necessary, no syllogistic conclusion can be drawn. This can be proved in the same way as for universal propositions, and by the same terms. Nor is a syllogistic conclusion possible 30when both premisses are affirmative: this also may be proved as above. But when both premisses are negative, and the premiss that definitely disconnects two terms is universal and necessary, though nothing follows necessarily from the premisses as they are stated, 35a conclusion can be drawn as above if the problematic premiss is converted into its complementary affirmative. But if both are indefinite or particular, no syllogism can be formed. The same proof will serve, and the same terms.
It is clear then from what has been said that if the universal and negative premiss is necessary, a syllogism is always possible, 40proving not merely a negative problematic, but also a negative assertoric proposition; but if the affirmative premiss is necessary no conclusion can be drawn.
But if the premisses are similar in quality, when they are negative a syllogism can always be formed by converting the problematic premiss into its complementary affirmative as before. Suppose A necessarily does not belong to B, 10and possibly may not belong to C: if the premisses are converted B belongs to no A, and A may possibly belong to all C: thus we have the first figure. Similarly if the minor premiss is negative. But if the premisses are affirmative there cannot be a syllogism. Clearly the conclusion cannot be 15a negative assertoric or a negative necessary proposition because no negative premiss has been laid down either in the assertoric or in the necessary mode. Nor can the conclusion be a problematic negative proposition. For if the terms are so related, there are cases in which B necessarily will not belong to C; e.g. suppose 20that A is white, B swan, C man. Nor can the opposite affirmations be established, since we have shown a case in which B necessarily does not belong to C. A syllogism then is not possible at all.
Similar relations will obtain in particular syllogisms. 25For whenever the negative proposition is universal and necessary, a syllogism will always be possible to prove both a problematic and a negative assertoric proposition (the proof proceeds by conversion); but when the affirmative proposition is universal and necessary, no syllogistic conclusion can be drawn. This can be proved in the same way as for universal propositions, and by the same terms. Nor is a syllogistic conclusion possible 30when both premisses are affirmative: this also may be proved as above. But when both premisses are negative, and the premiss that definitely disconnects two terms is universal and necessary, though nothing follows necessarily from the premisses as they are stated, 35a conclusion can be drawn as above if the problematic premiss is converted into its complementary affirmative. But if both are indefinite or particular, no syllogism can be formed. The same proof will serve, and the same terms.
It is clear then from what has been said that if the universal and negative premiss is necessary, a syllogism is always possible, 40proving not merely a negative problematic, but also a negative assertoric proposition; but if the affirmative premiss is necessary no conclusion can be drawn.
39a
1 ὑπάρχουσι γίνεταί τε καὶ οὐ γίνεται συλλογισμός. δῆλον
δὲ καὶ ὅτι πάντες ἀτελεῖς οἱ συλλογισμοί, καὶ ὅτι τελειοῦνται
διὰ τῶν προειρημένων σχημάτων.
1It is clear too that a syllogism is possible or not under the same conditions whether the mode of the premisses is assertoric or necessary. And it is clear that all the syllogisms are imperfect, and are completed by means of the figures mentioned.
Book 1,Chapter 20 (39a4–39b6)
Ἐν δὲ τῷ τελευταίῳ σχήματι καὶ ἀμφοτέρων ἐνδεχομένων
5 καὶ τῆς ἑτέρας ἔσται συλλογισμός. ὅταν μὲν
οὖν ἐνδέχεσθαι σημαίνωσιν αἱ προτάσεις, καὶ τὸ συμπέρασμα
ἔσται ἐνδεχόμενον· καὶ ὅταν ἡ μὲν ἐνδέχεσθαι ἡ δ'
ὑπάρχειν. ὅταν δ' ἡ ἑτέρα τεθῇ ἀναγκαία, ἐὰν μὲν ᾖ καταφατική,
οὐκ ἔσται τὸ συμπέρασμα οὔτε ἀναγκαῖον
10 οὔθ' ὑπάρχον, ἐὰν δ' ᾖ στερητική, τοῦ μὴ ὑπάρχειν ἔσται
συλλογισμός, καθάπερ καὶ ἐν τοῖς πρότερον· ληπτέον δὲ
καὶ ἐν τούτοις ὁμοίως τὸ ἐν τοῖς συμπεράσμασιν ἐνδεχόμενον.
Ἔστωσαν δὴ πρῶτον ἐνδεχόμεναι, καὶ τὸ Α καὶ τὸ
15 Β παντὶ τῷ Γ ἐνδεχέσθω ὑπάρχειν. ἐπεὶ οὖν ἀντιστρέφει
τὸ καταφατικὸν ἐπὶ μέρους, τὸ δὲ Β παντὶ τῷ Γ ἐνδέχεται,
καὶ τὸ Γ τινὶ τῷ Β ἐνδέχοιτ' ἄν. ὥστ' εἰ τὸ μὲν
Α παντὶ τῷ Γ ἐνδέχεται, τὸ δὲ Γ τινὶ τῷ Β, ἀνάγκη καὶ τὸ Α
τινὶ τῷ Β ἐνδέχεσθαι· γίγνεται γὰρ τὸ πρῶτον σχῆμα. καὶ
20 εἰ τὸ μὲν Α ἐνδέχεται μηδενὶ τῷ Γ ὑπάρχειν, τὸ δὲ Β
παντὶ τῷ Γ, ἀνάγκη τὸ Α τινὶ τῷ Β ἐνδέχεσθαι μὴ ὑπάρχειν·
ἔσται γὰρ πάλιν τὸ πρῶτον σχῆμα διὰ τῆς ἀντιστροφῆς.
εἰ δ' ἀμφότεραι στερητικαὶ τεθείησαν, ἐξ αὐτῶν
μὲν τῶν εἰλημμένων οὐκ ἔσται τὸ ἀναγκαῖον, ἀντιστραφεισῶν
25 δὲ τῶν προτάσεων ἔσται συλλογισμός, καθάπερ ἐν
τοῖς πρότερον. εἰ γὰρ τὸ Α καὶ τὸ Β τῷ Γ ἐνδέχεται μὴ
ὑπάρχειν, ἐὰν μεταληφθῇ τὸ ἐνδέχεσθαι ὑπάρχειν, πάλιν
ἔσται τὸ πρῶτον σχῆμα διὰ τῆς ἀντιστροφῆς. εἰ δ' ὁ μέν
ἐστι καθόλου τῶν ὅρων ὁ δ' ἐν μέρει, τὸν αὐτὸν τρόπον
30 ἐχόντων τῶν ὅρων ὅνπερ ἐπὶ τοῦ ὑπάρχειν, ἔσται τε καὶ
οὐκ ἔσται συλλογισμός. ἐνδεχέσθω γὰρ τὸ μὲν Α παντὶ
τῷ Γ, τὸ δὲ Β τινὶ τῷ Γ ὑπάρχειν. ἔσται δὴ πάλιν τὸ
πρῶτον σχῆμα τῆς ἐν μέρει προτάσεως ἀντιστραφείσης· εἰ
γὰρ τὸ Α παντὶ τῷ Γ, τὸ δὲ Γ τινὶ τῷ Β, τὸ Α τινὶ
35 τῷ Β ἐνδέχεται. καὶ εἰ πρὸς τῷ Β Γ τεθείη τὸ καθόλου,
ὡσαύτως. ὁμοίως δὲ καὶ εἰ τὸ μὲν Α Γ στερητικὸν εἴη, τὸ
δὲ Β Γ καταφατικόν· ἔσται γὰρ πάλιν τὸ πρῶτον σχῆμα
διὰ τῆς ἀντιστροφῆς. εἰ δ' ἀμφότεραι στερητικαὶ τεθείησαν,
ἡ μὲν καθόλου ἡ δ' ἐν μέρει, δι' αὐτῶν μὲν τῶν εἰλημμένων
4In the last figure a syllogism is possible whether both or only one of the premisses is problematic. When the premisses are problematic the conclusion will be problematic; 5and also when one premiss is problematic, the other assertoric. But when the other premiss is necessary, if it is affirmative the conclusion will be neither necessary 10or assertoric; but if it is negative the syllogism will result in a negative assertoric proposition, as above. In these also we must understand the expression 'possible' in the conclusion in the same way as before.
First let the premisses be problematic and suppose that both A and B may possibly belong to every C. 15Since then the affirmative proposition is convertible into a particular, and B may possibly belong to every C, it follows that C may possibly belong to some B. So, if A is possible for every C, and C is possible for some of the Bs, then A is possible for some of the Bs. For we have got the first figure. And A if 20may possibly belong to no C, but B may possibly belong to all C, it follows that A may possibly not belong to some B: for we shall have the first figure again by conversion. But if both premisses should be negative no necessary consequence will follow from them as they are stated, but if the premisses 25are converted into their corresponding affirmatives there will be a syllogism as before. For if A and B may possibly not belong to C, if 'may possibly belong' is substituted we shall again have the first figure by means of conversion. But if one of the premisses is universal, the other particular, a syllogism will be possible, or not, 30under the arrangement of the terms as in the case of assertoric propositions. Suppose that A may possibly belong to all C, and B to some C. We shall have the first figure again if the particular premiss is converted. For if A is possible for all C, and C for some of the Bs, then A is possible for some of the Bs. 35Similarly if the proposition BC is universal. Likewise also if the proposition AC is negative, and the proposition BC affirmative: for we shall again have the first figure by conversion. But if both premisses should be negative-the one universal and the other particular-although no syllogistic conclusion will follow from the premisses as they are put, it will follow if they are converted, as above.
First let the premisses be problematic and suppose that both A and B may possibly belong to every C. 15Since then the affirmative proposition is convertible into a particular, and B may possibly belong to every C, it follows that C may possibly belong to some B. So, if A is possible for every C, and C is possible for some of the Bs, then A is possible for some of the Bs. For we have got the first figure. And A if 20may possibly belong to no C, but B may possibly belong to all C, it follows that A may possibly not belong to some B: for we shall have the first figure again by conversion. But if both premisses should be negative no necessary consequence will follow from them as they are stated, but if the premisses 25are converted into their corresponding affirmatives there will be a syllogism as before. For if A and B may possibly not belong to C, if 'may possibly belong' is substituted we shall again have the first figure by means of conversion. But if one of the premisses is universal, the other particular, a syllogism will be possible, or not, 30under the arrangement of the terms as in the case of assertoric propositions. Suppose that A may possibly belong to all C, and B to some C. We shall have the first figure again if the particular premiss is converted. For if A is possible for all C, and C for some of the Bs, then A is possible for some of the Bs. 35Similarly if the proposition BC is universal. Likewise also if the proposition AC is negative, and the proposition BC affirmative: for we shall again have the first figure by conversion. But if both premisses should be negative-the one universal and the other particular-although no syllogistic conclusion will follow from the premisses as they are put, it will follow if they are converted, as above.
39b
1 οὐκ ἔσται συλλογισμός, ἀντιστραφεισῶν δ' ἔσται, καθάπερ
ἐν τοῖς πρότερον. ὅταν δὲ ἀμφότεραι ἀδιόριστοι ἢ
ἐν μέρει ληφθῶσιν, οὐκ ἔσται συλλογισμός· καὶ γὰρ παντὶ
ἀνάγκη τὸ Α τῷ Β καὶ μηδενὶ ὑπάρχειν. ὅροι τοῦ ὑπάρχειν
5 ζῷον—ἄνθρωπος—λευκόν, τοῦ μὴ ὑπάρχειν ἵππος—ἄνθρωπος—λευκόν,
μέσον λευκόν.
1But when both premisses are indefinite or particular, no syllogism can be formed: for A must belong sometimes to all B and sometimes to no B. To illustrate the affirmative relation take the terms 5animal-man-white; to illustrate the negative, take the terms horse-man-white--white being the middle term.
Book 1,Chapter 21 (39b7–40a3)
Ἐὰν δὲ ἡ μὲν ὑπάρχειν ἡ δ' ἐνδέχεσθαι σημαίνῃ
τῶν προτάσεων, τὸ μὲν συμπέρασμα ἔσται ὅτι ἐνδέχεται
καὶ οὐχ ὅτι ὑπάρχει, συλλογισμὸς δ' ἔσται τὸν αὐτὸν τρόπον
10 ἐχόντων τῶν ὅρων ὃν καὶ ἐν τοῖς πρότερον. ἔστωσαν γὰρ
πρῶτον κατηγορικοί, καὶ τὸ μὲν Α παντὶ τῷ Γ ὑπαρχέτω,
τὸ δὲ Β παντὶ ἐνδεχέσθω ὑπάρχειν. ἀντιστραφέντος οὖν τοῦ
Β Γ τὸ πρῶτον ἔσται σχῆμα, καὶ τὸ συμπέρασμα ὅτι ἐνδέχεται
τὸ Α τινὶ τῷ Β ὑπάρχειν· ὅτε γὰρ ἡ ἑτέρα τῶν
15 προτάσεων ἐν τῷ πρώτῳ σχήματι σημαίνοι ἐνδέχεσθαι, καὶ
τὸ συμπέρασμα ἦν ἐνδεχόμενον. ὁμοίως δὲ καὶ εἰ τὸ μὲν
Β Γ ὑπάρχειν τὸ δὲ Α Γ ἐνδέχεσθαι, καὶ εἰ τὸ μὲν Α Γ
στερητικὸν τὸ δὲ Β Γ κατηγορικόν, ὑπάρχοι δ' ὁποτερονοῦν,
ἀμφοτέρως ἐνδεχόμενον ἔσται τὸ συμπέρασμα· γίνεται γὰρ
20 πάλιν τὸ πρῶτον σχῆμα, δέδεικται δ' ὅτι τῆς ἑτέρας προτάσεως
ἐνδέχεσθαι σημαινούσης ἐν αὐτῷ καὶ τὸ συμπέρασμα
ἔσται ἐνδεχόμενον. εἰ δὲ τὸ στερητικὸν τεθείη πρὸς
τὸ ἔλαττον ἄκρον, ἢ καὶ ἄμφω ληφθείη στερητικά, δι'
αὐτῶν μὲν τῶν κειμένων οὐκ ἔσται συλλογισμός, ἀντιστραφέντων
25 δ' ἔσται, καθάπερ ἐν τοῖς πρότερον.
Εἰ δ' ἡ μὲν καθόλου τῶν προτάσεων ἡ δ' ἐν μέρει,
κατηγορικῶν μὲν οὐσῶν ἀμφοτέρων, ἢ τῆς μὲν καθόλου
στερητικῆς τῆς δ' ἐν μέρει καταφατικῆς, ὁ αὐτὸς τρόπος
ἔσται τῶν συλλογισμῶν· πάντες γὰρ περαίνονται διὰ τοῦ
30 πρώτου σχήματος. ὥστε φανερὸν ὅτι τοῦ ἐνδέχεσθαι καὶ οὐ
τοῦ ὑπάρχειν ἔσται ὁ συλλογισμός. εἰ δ' ἡ μὲν καταφατικὴ
καθόλου ἡ δὲ στερητικὴ ἐν μέρει, διὰ τοῦ ἀδυνάτου ἔσται
ἡ ἀπόδειξις. ὑπαρχέτω γὰρ τὸ μὲν Β παντὶ τῷ Γ, τὸ δὲ
Α ἐνδεχέσθω τινὶ τῷ Γ μὴ ὑπάρχειν· ἀνάγκη δὴ τὸ Α ἐνδέχεσθαι
35 τινὶ τῷ Β μὴ ὑπάρχειν. εἰ γὰρ παντὶ τῷ Β τὸ
Α ὑπάρχει ἐξ ἀνάγκης, τὸ δὲ Β παντὶ τῷ Γ κεῖται ὑπάρχειν,
τὸ Α παντὶ τῷ Γ ἐξ ἀνάγκης ὑπάρξει· τοῦτο γὰρ
δέδεικται πρότερον. ἀλλ' ὑπέκειτο τινὶ ἐνδέχεσθαι μὴ
ὑπάρχειν.
7If one premiss is pure, the other problematic, the conclusion will be problematic, not pure; and a syllogism will be possible 10under the same arrangement of the terms as before. First let the premisses be affirmative: suppose that A belongs to all C, and B may possibly belong to all C. If the proposition BC is converted, we shall have the first figure, and the conclusion that A may possibly belong to some of the Bs. For when one 15of the premisses in the first figure is problematic, the conclusion also (as we saw) is problematic. Similarly if the proposition BC is pure, AC problematic; or if AC is negative, Bc affirmative, no matter which of the two is pure; in both cases the conclusion will be problematic: for 20the first figure is obtained once more, and it has been proved that if one premiss is problematic in that figure the conclusion also will be problematic. But if the minor premiss BC is negative, or if both premisses are negative, no syllogistic conclusion can be drawn from the premisses as they stand, but if they are converted 25a syllogism is obtained as before.
If one of the premisses is universal, the other particular, then when both are affirmative, or when the universal is negative, the particular affirmative, we shall have the same sort of syllogisms: for all are completed by means of 30the first figure. So it is clear that we shall have not a pure but a problematic syllogistic conclusion. But if the affirmative premiss is universal, the negative particular, the proof will proceed by a reductio ad impossibile. Suppose that B belongs to all C, and A may possibly not belong to some C: it follows that may possibly not belong to some B. 35For if A necessarily belongs to all B, and B (as has been assumed) belongs to all C, A will necessarily belong to all C: for this has been proved before. But it was assumed at the outset that A may possibly not belong to some C.
If one of the premisses is universal, the other particular, then when both are affirmative, or when the universal is negative, the particular affirmative, we shall have the same sort of syllogisms: for all are completed by means of 30the first figure. So it is clear that we shall have not a pure but a problematic syllogistic conclusion. But if the affirmative premiss is universal, the negative particular, the proof will proceed by a reductio ad impossibile. Suppose that B belongs to all C, and A may possibly not belong to some C: it follows that may possibly not belong to some B. 35For if A necessarily belongs to all B, and B (as has been assumed) belongs to all C, A will necessarily belong to all C: for this has been proved before. But it was assumed at the outset that A may possibly not belong to some C.
40a
1 Ὅταν δ' ἀδιόριστοι ἢ ἐν μέρει ληφθῶσιν ἀμφότεραι,
οὐκ ἔσται συλλογισμός. ἀπόδειξις δ' ἡ αὐτὴ ἣ καὶ ἐν τοῖς
πρότερον, καὶ διὰ τῶν αὐτῶν ὅρων.
1Whenever both premisses are indefinite or particular, no syllogism will be possible. The demonstration is the same as was given in the case of universal premisses, and proceeds by means of the same terms.
Book 1,Chapter 22 (40a4–40b16)
Εἰ δ' ἐστὶν ἡ μὲν ἀναγκαία τῶν προτάσεων ἡ δ' ἐνδεχομένη,
5 κατηγορικῶν μὲν ὄντων τῶν ὅρων ἀεὶ τοῦ ἐνδέχεσθαι
ἔσται συλλογισμός, ὅταν δ' ᾖ τὸ μὲν κατηγορικὸν τὸ
δὲ στερητικόν, ἐὰν μὲν ᾖ τὸ καταφατικὸν ἀναγκαῖον, τοῦ ἐνδέχεσθαι
μὴ ὑπάρχειν, ἐὰν δὲ τὸ στερητικόν, καὶ τοῦ ἐνδέχεσθαι
καὶ τοῦ μὴ ὑπάρχειν. τοῦ δ' ἐξ ἀνάγκης
10 μὴ ὑπάρχειν οὐκ ἔσται συλλογισμός, ὥσπερ οὐδ' ἐν τοῖς
ἑτέροις σχήμασιν. Ἔστωσαν δὴ κατηγορικοὶ πρῶτον οἱ ὅροι,
καὶ τὸ μὲν Α παντὶ τῷ Γ ὑπαρχέτω ἐξ ἀνάγκης, τὸ δὲ
Β παντὶ ἐνδεχέσθω ὑπάρχειν. ἐπεὶ οὖν τὸ μὲν Α παντὶ
τῷ Γ ἀνάγκη, τὸ δὲ Γ τινὶ τῷ Β ἐνδέχεται, καὶ τὸ Α
15 τινὶ τῷ Β ἐνδεχόμενον ἔσται καὶ οὐχ ὑπάρχον· οὕτω γὰρ
συνέπιπτεν ἐπὶ τοῦ πρώτου σχήματος. ὁμοίως δὲ δειχθήσεται
καὶ εἰ τὸ μὲν Β Γ τεθείη ἀναγκαῖον, τὸ δὲ Α Γ ἐνδεχόμενον.
πάλιν ἔστω τὸ μὲν κατηγορικὸν τὸ δὲ στερητικόν,
ἀναγκαῖον δὲ τὸ κατηγορικόν· καὶ τὸ μὲν Α ἐνδεχέσθω μηδενὶ
20 τῷ Γ ὑπάρχειν, τὸ δὲ Β παντὶ ὑπαρχέτω ἐξ ἀνάγκης.
ἔσται δὴ πάλιν τὸ πρῶτον σχῆμα· καὶ γὰρ ἡ στερητικὴ
πρότασις ἐνδέχεσθαι σημαίνει· φανερὸν οὖν ὅτι τὸ συμπέρασμα
ἔσται ἐνδεχόμενον· ὅτε γὰρ οὕτως ἔχοιεν αἱ προτάσεις
ἐν τῷ πρώτῳ σχήματι, καὶ τὸ συμπέρασμα ἦν
25 ἐνδεχόμενον. εἰ δ' ἡ στερητικὴ πρότασις ἀναγκαία, τὸ συμπέρασμα
ἔσται καὶ ὅτι ἐνδέχεται τινὶ μὴ ὑπάρχειν καὶ ὅτι
οὐχ ὑπάρχει. κείσθω γὰρ τὸ Α τῷ Γ μὴ ὑπάρχειν ἐξ ἀνάγκης,
τὸ δὲ Β παντὶ ἐνδέχεσθαι. ἀντιστραφέντος οὖν τοῦ Β
Γ καταφατικοῦ τὸ πρῶτον ἔσται σχῆμα, καὶ ἀναγκαία ἡ
30 στερητικὴ πρότασις. ὅτε δ' οὕτως ἔχοιεν αἱ προτάσεις, συνέβαινε
τὸ Α τῷ Γ καὶ ἐνδέχεσθαι τινὶ μὴ ὑπάρχειν καὶ μὴ
ὑπάρχειν, ὥστε καὶ τὸ Α τῷ Β ἀνάγκη τινὶ μὴ ὑπάρχειν.
ὅταν δὲ τὸ στερητικὸν τεθῇ πρὸς τὸ ἔλαττον ἄκρον, ἐὰν μὲν
ἐνδεχόμενον, ἔσται συλλογισμὸς μεταληφθείσης τῆς προτάσεως,
35 καθάπερ ἐν τοῖς πρότερον, ἐὰν δ' ἀναγκαῖον, οὐκ ἔσται·
καὶ γὰρ παντὶ ἀνάγκη καὶ οὐδενὶ ἐνδέχεται ὑπάρχειν. ὅροι
τοῦ παντὶ ὑπάρχειν ὕπνος—ἵππος καθεύδων—ἄνθρωπος, τοῦ
μηδενὶ ὕπνος—ἵππος ἐγρηγορώς—ἄνθρωπος.
Ὁμοίως δ' ἕξει καὶ εἰ ὁ μὲν καθόλου τῶν ὅρων ὁ δ'
40 ἐν μέρει πρὸς τὸ μέσον· κατηγορικῶν μὲν γὰρ ὄντων ἀμφοτέρων
4If one of the premisses is necessary, the other problematic, 5when the premisses are affirmative a problematic affirmative conclusion can always be drawn; when one proposition is affirmative, the other negative, if the affirmative is necessary a problematic negative can be inferred; but if the negative proposition is necessary both a problematic and a pure negative conclusion are possible. But a necessary negative conclusion 10will not be possible, any more than in the other figures. Suppose first that the premisses are affirmative, i.e. that A necessarily belongs to all C, and B may possibly belong to all C. Since then A must belong to all C, and C may belong to some B, 15it follows that A may (not does) belong to some B: for so it resulted in the first figure. A similar proof may be given if the proposition BC is necessary, and AC is problematic. Again suppose one proposition is affirmative, the other negative, the affirmative being necessary: i.e. suppose A may possibly belong to no C, 20but B necessarily belongs to all C. We shall have the first figure once more: and-since the negative premiss is problematic-it is clear that the conclusion will be problematic: for when the premisses stand thus in the first figure, the conclusion (as we found) is problematic. 25But if the negative premiss is necessary, the conclusion will be not only that A may possibly not belong to some B but also that it does not belong to some B. For suppose that A necessarily does not belong to C, but B may belong to all C. If the affirmative proposition BC is converted, we shall have the first figure, 30and the negative premiss is necessary. But when the premisses stood thus, it resulted that A might possibly not belong to some C, and that it did not belong to some C; consequently here it follows that A does not belong to some B. But when the minor premiss is negative, if it is problematic we shall have a syllogism by altering the premiss into its complementary affirmative, 35as before; but if it is necessary no syllogism can be formed. For A sometimes necessarily belongs to all B, and sometimes cannot possibly belong to any B. To illustrate the former take the terms sleep-sleeping horse-man; to illustrate the latter take the terms sleep-waking horse-man.
Similar results will obtain if one of the terms is related universally to the middle, 40the other in part.
Similar results will obtain if one of the terms is related universally to the middle, 40the other in part.
40b
1 τοῦ ἐνδέχεσθαι καὶ οὐ τοῦ ὑπάρχειν ἔσται συλλογισμός,
καὶ ὅταν τὸ μὲν στερητικὸν ληφθῇ τὸ δὲ καταφατικόν,
ἀναγκαῖον δὲ τὸ καταφατικόν. ὅταν δὲ τὸ στερητικὸν
ἀναγκαῖον, καὶ τὸ συμπέρασμα ἔσται τοῦ μὴ ὑπάρχειν· ὁ γὰρ
5 αὐτὸς τρόπος ἔσται τῆς δείξεως καὶ καθόλου καὶ μὴ καθόλου
τῶν ὅρων ὄντων. ἀνάγκη γὰρ διὰ τοῦ πρώτου σχήματος τελειοῦσθαι
τοὺς συλλογισμούς, ὥστε καθάπερ ἐν ἐκείνοις, καὶ
ἐπὶ τούτων ἀναγκαῖον συμπίπτειν. ὅταν δὲ τὸ στερητικὸν
καθόλου ληφθὲν τεθῇ πρὸς τὸ ἔλαττον ἄκρον, ἐὰν μὲν ἐνδεχόμενον,
10 ἔσται συλλογισμὸς διὰ τῆς ἀντιστροφῆς, ἐὰν δ'
ἀναγκαῖον, οὐκ ἔσται. δειχθήσεται δὲ τὸν αὐτὸν τρόπον ὃν
καὶ ἐν τοῖς καθόλου, καὶ διὰ τῶν αὐτῶν ὅρων. φανερὸν
οὖν καὶ ἐν τούτῳ τῷ σχήματι πότε καὶ πῶς ἔσται συλλογισμός,
καὶ πότε τοῦ ἐνδέχεσθαι καὶ πότε τοῦ ὑπάρχειν.
15 δῆλον δὲ καὶ ὅτι πάντες ἀτελεῖς, καὶ ὅτι τελειοῦνται διὰ
τοῦ πρώτου σχήματος.
1If both premisses are affirmative, the conclusion will be problematic, not pure; and also when one premiss is negative, the other affirmative, the latter being necessary. But when the negative premiss is necessary, the conclusion also will be a pure negative proposition; 5for the same kind of proof can be given whether the terms are universal or not. For the syllogisms must be made perfect by means of the first figure, so that a result which follows in the first figure follows also in the third. But when the minor premiss is negative and universal, if it is problematic 10a syllogism can be formed by means of conversion; but if it is necessary a syllogism is not possible. The proof will follow the same course as where the premisses are universal; and the same terms may be used.
It is clear then in this figure also when and how a syllogism can be formed, and when the conclusion is problematic, and when it is pure. 15It is evident also that all syllogisms in this figure are imperfect, and that they are made perfect by means of the first figure.
It is clear then in this figure also when and how a syllogism can be formed, and when the conclusion is problematic, and when it is pure. 15It is evident also that all syllogisms in this figure are imperfect, and that they are made perfect by means of the first figure.
Book 1,Chapter 23 (40b17–41b5)
Ὅτι μὲν οὖν οἱ ἐν τούτοις τοῖς σχήμασι συλλογισμοὶ
τελειοῦνταί τε διὰ τῶν ἐν τῷ πρώτῳ σχήματι καθόλου
συλλογισμῶν καὶ εἰς τούτους ἀνάγονται, δῆλον ἐκ τῶν εἰρημένων·
20 ὅτι δ' ἁπλῶς πᾶς συλλογισμὸς οὕτως ἕξει, νῦν
ἔσται φανερόν, ὅταν δειχθῇ πᾶς γινόμενος διὰ τούτων τινὸς
τῶν σχημάτων.
Ἀνάγκη δὴ πᾶσαν ἀπόδειξεν καὶ πάντα συλλογισμὸν
ἢ ὑπάρχον τι ἢ μὴ ὑπάρχον δεικνύναι, καὶ τοῦτο ἢ καθόλου
25 ἢ κατὰ μέρος, ἔτι ἢ δεικτικῶς ἢ ἐξ ὑποθέσεως. τοῦ δ' ἐξ
ὑποθέσεως μέρος τὸ διὰ τοῦ ἀδυνάτου. πρῶτον οὖν εἴπωμεν
περὶ τῶν δεικτικῶν· τούτων γὰρ δειχθέντων φανερὸν
ἔσται καὶ ἐπὶ τῶν εἰς τὸ ἀδύνατον καὶ ὅλως τῶν ἐξ ὑποθέσεως.
30 Εἰ δὴ δέοι τὸ Α κατὰ τοῦ Β συλλογίσασθαι ἢ ὑπάρχον
ἢ μὴ ὑπάρχον, ἀνάγκη λαβεῖν τι κατά τινος. εἰ μὲν
οὖν τὸ Α κατὰ τοῦ Β ληφθείη, τὸ ἐξ ἀρχῆς ἔσται εἰλημμένον.
εἰ δὲ κατὰ τοῦ Γ, τὸ δὲ Γ κατὰ μηδενός, μηδ'
ἄλλο κατ' ἐκείνου, μηδὲ κατὰ τοῦ Α ἕτερον, οὐδεὶς ἔσται
35 συλλογισμός· τῷ γὰρ ἓν καθ' ἑνὸς ληφθῆναι οὐδὲν συμβαίνει
ἐξ ἀνάγκης. ὥστε προσληπτέον καὶ ἑτέραν πρότασιν.
ἐὰν μὲν οὖν ληφθῇ τὸ Α κατ' ἄλλου ἢ ἄλλο κατὰ
τοῦ Α, ἢ κατὰ τοῦ Γ ἕτερον, εἶναι μὲν συλλογισμὸν οὐδὲν
κωλύει, πρὸς μέντοι τὸ Β οὐκ ἔσται διὰ τῶν εἰλημμένων.
40 οὐδ' ὅταν τὸ Γ ἑτέρῳ, κἀκεῖνο ἄλλῳ, καὶ τοῦτο ἑτέρῳ, μὴ
17It is clear from what has been said that the syllogisms in these figures are made perfect by means of universal syllogisms in the first figure and are reduced to them. 20That every syllogism without qualification can be so treated, will be clear presently, when it has been proved that every syllogism is formed through one or other of these figures.
It is necessary that every demonstration and every syllogism should prove either that something belongs or that it does not, and this either universally 25or in part, and further either ostensively or hypothetically. One sort of hypothetical proof is the reductio ad impossibile. Let us speak first of ostensive syllogisms: for after these have been pointed out the truth of our contention will be clear with regard to those which are proved per impossibile, and in general hypothetically.
30If then one wants to prove syllogistically A of B, either as an attribute of it or as not an attribute of it, one must assert something of something else. If now A should be asserted of B, the proposition originally in question will have been assumed. But if A should be asserted of C, but C should not be asserted of anything, nor anything of it, nor anything else of A, 35no syllogism will be possible. For nothing necessarily follows from the assertion of some one thing concerning some other single thing. Thus we must take another premiss as well. 40If then A be asserted of something else, or something else of A, or something different of C, nothing prevents a syllogism being formed, but it will not be in relation to B through the premisses taken.
It is necessary that every demonstration and every syllogism should prove either that something belongs or that it does not, and this either universally 25or in part, and further either ostensively or hypothetically. One sort of hypothetical proof is the reductio ad impossibile. Let us speak first of ostensive syllogisms: for after these have been pointed out the truth of our contention will be clear with regard to those which are proved per impossibile, and in general hypothetically.
30If then one wants to prove syllogistically A of B, either as an attribute of it or as not an attribute of it, one must assert something of something else. If now A should be asserted of B, the proposition originally in question will have been assumed. But if A should be asserted of C, but C should not be asserted of anything, nor anything of it, nor anything else of A, 35no syllogism will be possible. For nothing necessarily follows from the assertion of some one thing concerning some other single thing. Thus we must take another premiss as well. 40If then A be asserted of something else, or something else of A, or something different of C, nothing prevents a syllogism being formed, but it will not be in relation to B through the premisses taken.
41a
1 συνάπτῃ δὲ πρὸς τὸ Β, οὐδ' οὕτως ἔσται πρὸς τὸ Β συλλογισμός.
ὅλως γὰρ εἴπομεν ὅτι οὐδεὶς οὐδέποτε ἔσται
συλλογισμὸς ἄλλου κατ' ἄλλου μὴ ληφθέντος τινὸς μέσου,
ὃ πρὸς ἑκάτερον ἔχει πως ταῖς κατηγορίαις· ὁ μὲν
5 γὰρ συλλογισμὸς ἁπλῶς ἐκ προτάσεών ἐστιν, ὁ δὲ πρὸς
τόδε συλλογισμὸς ἐκ τῶν πρὸς τόδε προτάσεων, ὁ δὲ τοῦδε
πρὸς τόδε διὰ τῶν τοῦδε πρὸς τόδε προτάσεων. ἀδύνατον δὲ
πρὸς τὸ Β λαβεῖν πρότασιν μηδὲν μήτε κατηγοροῦντας
αὐτοῦ μήτ' ἀπαρνουμένους, ἢ πάλιν τοῦ Α πρὸς τὸ Β μηδὲν
10 κοινὸν λαμβάνοντας ἀλλ' ἑκατέρου ἴδια ἄττα κατηγοροῦντας
ἢ ἀπαρνουμένους. ὥστε ληπτέον τι μέσον ἀμφοῖν,
ὃ συνάψει τὰς κατηγορίας, εἴπερ ἔσται τοῦδε πρὸς τόδε συλλογισμός.
εἰ οὖν ἀνάγκη μέν τι λαβεῖν πρὸς ἄμφω κοινόν,
τοῦτο δ' ἐνδέχεται τριχῶς (ἢ γὰρ τὸ Α τοῦ Γ καὶ τὸ Γ
15 τοῦ Β κατηγορήσαντας, ἢ τὸ Γ κατ' ἀμφοῖν, ἢ ἄμφω
κατὰ τοῦ Γ), ταῦτα δ' ἐστὶ τὰ εἰρημένα σχήματα, φανερὸν
ὅτι πάντα συλλογισμὸν ἀνάγκη γίνεσθαι διὰ τούτων
τινὸς τῶν σχημάτων. ὁ γὰρ αὐτὸς λόγος καὶ εἰ διὰ πλειόνων
συνάπτοι πρὸς τὸ Β· ταὐτὸ γὰρ ἔσται σχῆμα καὶ
20 ἐπὶ τῶν πολλῶν.
Ὅτι μὲν οὖν οἱ δεικτικοὶ περαίνονται διὰ τῶν προειρημένων
σχημάτων, φανερόν· ὅτι δὲ καὶ οἱ εἰς τὸ ἀδύνατον, δῆλον
ἔσται διὰ τούτων. πάντες γὰρ οἱ διὰ τοῦ ἀδυνάτου περαίνοντες
τὸ μὲν ψεῦδος συλλογίζονται, τὸ δ' ἐξ ἀρχῆς ἐξ
25 ὑποθέσεως δεικνύουσιν, ὅταν ἀδύνατόν τι συμβαίνῃ τῆς ἀντιφάσεως
τεθείσης, οἷον ὅτι ἀσύμμετρος ἡ διάμετρος διὰ τὸ γίνεσθαι
τὰ περιττὰ ἴσα τοῖς ἀρτίοις συμμέτρου τεθείσης. τὸ μὲν
οὖν ἴσα γίνεσθαι τὰ περιττὰ τοῖς ἀρτίοις συλλογίζεται, τὸ
δ' ἀσύμμετρον εἶναι τὴν διάμετρον ἐξ ὑποθέσεως δείκνυσιν,
30 ἐπεὶ ψεῦδος συμβαίνει διὰ τὴν ἀντίφασιν. τοῦτο γὰρ ἦν
τὸ διὰ τοῦ ἀδυνάτου συλλογίσασθαι, τὸ δεῖξαί τι ἀδύνατον
διὰ τὴν ἐξ ἀρχῆς ὑπόθεσιν. ὥστ' ἐπεὶ τοῦ ψεύδους γίνεται
συλλογισμὸς δεικτικὸς ἐν τοῖς εἰς τὸ ἀδύνατον ἀπαγομένοις,
τὸ δ' ἐξ ἀρχῆς ἐξ ὑποθέσεως δείκνυται, τοὺς δὲ
35 δεικτικοὺς πρότερον εἴπομεν ὅτι διὰ τούτων περαίνονται τῶν
σχημάτων, φανερὸν ὅτι καὶ οἱ διὰ τοῦ ἀδυνάτου συλλογισμοὶ
διὰ τούτων ἔσονται τῶν σχημάτων. ὡσαύτως δὲ
καὶ οἱ ἄλλοι πάντες οἱ ἐξ ὑποθέσεως· ἐν ἅπασι γὰρ ὁ
μὲν συλλογισμὸς γίνεται πρὸς τὸ μεταλαμβανόμενον, τὸ
40 δ' ἐξ ἀρχῆς περαίνεται δι' ὁμολογίας ἤ τινος ἄλλης ὑποθέσεως.
1Nor when C belongs to something else, and that to something else and so on, no connexion however being made with B, will a syllogism be possible concerning A in its relation to B. For in general we stated that no syllogism can establish the attribution of one thing to another, unless some middle term is taken, which is somehow related to each by way of predication. 5For the syllogism in general is made out of premisses, and a syllogism referring to this out of premisses with the same reference, and a syllogism relating this to that proceeds through premisses which relate this to that. But it is impossible to take a premiss in reference to B, if we neither affirm nor deny anything of it; or again to take a premiss relating A to B, if we take nothing common, 10but affirm or deny peculiar attributes of each. So we must take something midway between the two, which will connect the predications, if we are to have a syllogism relating this to that. If then we must take something common in relation to both, and this is possible in three ways (either by predicating A of C, 15and C of B, or C of both, or both of C), and these are the figures of which we have spoken, it is clear that every syllogism must be made in one or other of these figures. The argument is the same if several middle terms should be necessary to establish the relation to B; for the figure will be the same 20whether there is one middle term or many.
It is clear then that the ostensive syllogisms are effected by means of the aforesaid figures; these considerations will show that reductiones ad also are effected in the same way. For all who effect an argument per impossibile infer syllogistically what is false, 25and prove the original conclusion hypothetically when something impossible results from the assumption of its contradictory; e.g. that the diagonal of the square is incommensurate with the side, because odd numbers are equal to evens if it is supposed to be commensurate. One infers syllogistically that odd numbers come out equal to evens, and one proves hypothetically the incommensurability of the diagonal, 30since a falsehood results through contradicting this. For this we found to be reasoning per impossibile, viz. proving something impossible by means of an hypothesis conceded at the beginning. Consequently, since the falsehood is established in reductions ad impossibile by an ostensive syllogism, and the original conclusion is proved hypothetically, and 35we have already stated that ostensive syllogisms are effected by means of these figures, it is evident that syllogisms per impossibile also will be made through these figures. Likewise all the other hypothetical syllogisms: for in every case the syllogism leads up to the proposition that is substituted for the original thesis; 40but the original thesis is reached by means of a concession or some other hypothesis.
It is clear then that the ostensive syllogisms are effected by means of the aforesaid figures; these considerations will show that reductiones ad also are effected in the same way. For all who effect an argument per impossibile infer syllogistically what is false, 25and prove the original conclusion hypothetically when something impossible results from the assumption of its contradictory; e.g. that the diagonal of the square is incommensurate with the side, because odd numbers are equal to evens if it is supposed to be commensurate. One infers syllogistically that odd numbers come out equal to evens, and one proves hypothetically the incommensurability of the diagonal, 30since a falsehood results through contradicting this. For this we found to be reasoning per impossibile, viz. proving something impossible by means of an hypothesis conceded at the beginning. Consequently, since the falsehood is established in reductions ad impossibile by an ostensive syllogism, and the original conclusion is proved hypothetically, and 35we have already stated that ostensive syllogisms are effected by means of these figures, it is evident that syllogisms per impossibile also will be made through these figures. Likewise all the other hypothetical syllogisms: for in every case the syllogism leads up to the proposition that is substituted for the original thesis; 40but the original thesis is reached by means of a concession or some other hypothesis.
41b
1 εἰ δὲ τοῦτ' ἀληθές, πᾶσαν ἀπόδειξιν καὶ πάντα
συλλογισμὸν ἀνάγκη γίνεσθαι διὰ τριῶν τῶν προειρημένων
σχημάτων. τούτου δὲ δειχθέντος δῆλον ὡς ἅπας τε συλλογισμὸς
ἐπιτελεῖται διὰ τοῦ πρώτου σχήματος καὶ ἀνάγεται
5 εἰς τοὺς ἐν τούτῳ καθόλου συλλογισμούς.
1But if this is true, every demonstration and every syllogism must be formed by means of the three figures mentioned above. But when this has been shown it is clear that every syllogism is perfected by means of the first figure and 5is reducible to the universal syllogisms in this figure.
Book 1,Chapter 24 (41b6–35)
Ἔτι τε ἐν ἅπαντι δεῖ κατηγορικόν τινα τῶν ὅρων εἶναι
καὶ τὸ καθόλου ὑπάρχειν· ἄνευ γὰρ τοῦ καθόλου ἢ
οὐκ ἔσται συλλογισμὸς ἢ οὐ πρὸς τὸ κείμενον, ἢ τὸ ἐξ ἀρχῆς
αἰτήσεται. κείσθω γὰρ τὴν μουσικὴν ἡδονὴν εἶναι σπουδαίαν.
10 εἰ μὲν οὖν ἀξιώσειεν ἡδονὴν εἶναι σπουδαίαν μὴ προςθεὶς
τὸ πᾶσαν, οὐκ ἔσται συλλογισμός· εἰ δὲ τινὰ ἡδονήν,
εἰ μὲν ἄλλην, οὐδὲν πρὸς τὸ κείμενον, εἰ δ' αὐτὴν
ταύτην, τὸ ἐξ ἀρχῆς λαμβάνει. μᾶλλον δὲ γίνεται φανερὸν
ἐν τοῖς διαγράμμασιν, οἷον ὅτι τοῦ ἰσοσκελοῦς ἴσαι
15 αἱ πρὸς τῇ βάσει. ἔστωσαν εἰς τὸ κέντρον ἠγμέναι αἱ Α Β.
εἰ οὖν ἴσην λαμβάνοι τὴν Α Γ γωνίαν τῇ Β Δ μὴ ὅλως
ἀξιώσας ἴσας τὰς τῶν ἡμικυκλίων, καὶ πάλιν τὴν Γ
τῇ Δ μὴ πᾶσαν προσλαβὼν τὴν τοῦ τμήματος, ἔτι δ'
ἀπ' ἴσων οὐσῶν τῶν ὅλων γωνιῶν καὶ ἴσων ἀφῃρημένων
20 ἴσας εἶναι τὰς λοιπὰς τὰς Ε Ζ, τὸ ἐξ ἀρχῆς αἰτήσεται,
ἐὰν μὴ λάβῃ ἀπὸ τῶν ἴσων ἴσων ἀφαιρουμένων
ἴσα λείπεσθαι. φανερὸν οὖν ὅτι ἐν ἅπαντι δεῖ τὸ καθόλου
ὑπάρχειν, καὶ ὅτι τὸ μὲν καθόλου ἐξ ἁπάντων τῶν ὅρων
καθόλου δείκνυται, τὸ δ' ἐν μέρει καὶ οὕτως κἀκείνως, ὥστ'
25 ἐὰν μὲν ᾖ τὸ συμπέρασμα καθόλου, καὶ τοὺς ὅρους ἀνάγκη
καθόλου εἶναι, ἐὰν δ' οἱ ὅροι καθόλου, ἐνδέχεται τὸ συμπέρασμα
μὴ εἶναι καθόλου. δῆλον δὲ καὶ ὅτι ἐν ἅπαντι συλλογισμῷ
ἢ ἀμφοτέρας ἢ τὴν ἑτέραν πρότασιν ὁμοίαν ἀνάγκη γίνεσθαι
τῷ συμπεράσματι. λέγω δ' οὐ μόνον τῷ καταφατικὴν
30 εἶναι ἢ στερητικήν, ἀλλὰ καὶ τῷ ἀναγκαίαν ἢ ὑπάρχουσαν ἢ ἐνδεχομένην.
ἐπισκέψασθαι δὲ δεῖ καὶ τὰς ἄλλας κατηγορίας.
Φανερὸν δὲ καὶ ἁπλῶς πότ' ἔσται καὶ πότ' οὐκ ἔσται
συλλογισμός, καὶ πότε δυνατὸς καὶ πότε τέλειος, καὶ ὅτι
συλλογισμοῦ ὄντος ἀναγκαῖον ἔχειν τοὺς ὅρους κατά τινα
35 τῶν εἰρημένων τρόπων.
6Further in every syllogism one of the premisses must be affirmative, and universality must be present: unless one of the premisses is universal either a syllogism will not be possible, or it will not refer to the subject proposed, or the original position will be begged. Suppose we have to prove that pleasure in music is good. 10If one should claim as a premiss that pleasure is good without adding 'all', no syllogism will be possible; if one should claim that some pleasure is good, then if it is different from pleasure in music, it is not relevant to the subject proposed; if it is this very pleasure, one is assuming that which was proposed at the outset to be proved. This is more obvious in geometrical proofs, e.g. that the angles at the base of an isosceles triangle are equal. Suppose 15the lines A and B have been drawn to the centre. If then one should assume that the angle AC is equal to the angle BD, without claiming generally that angles of semicircles are equal; and again if one should assume that the angle C is equal to the angle D, without the additional assumption that every angle of a segment is equal to every other angle of the same segment; and further if one should assume that when equal angles are taken from the whole angles, which are themselves equal, 20the remainders E and F are equal, he will beg the thing to be proved, unless he also states that when equals are taken from equals the remainders are equal.
It is clear then that in every syllogism there must be a universal premiss, and that a universal statement is proved only when all the premisses are universal, while a particular statement is proved both from two universal premisses and from one only: consequently 25if the conclusion is universal, the premisses also must be universal, but if the premisses are universal it is possible that the conclusion may not be universal. And it is clear also that in every syllogism either both or one of the premisses must be like the conclusion. I mean not only in being affirmative 30or negative, but also in being necessary, pure, problematic. We must consider also the other forms of predication.
It is clear also when a syllogism in general can be made and when it cannot; and when a valid, when a perfect syllogism can be formed; and that if a syllogism is formed the terms must be arranged 35in one of the ways that have been mentioned.
It is clear then that in every syllogism there must be a universal premiss, and that a universal statement is proved only when all the premisses are universal, while a particular statement is proved both from two universal premisses and from one only: consequently 25if the conclusion is universal, the premisses also must be universal, but if the premisses are universal it is possible that the conclusion may not be universal. And it is clear also that in every syllogism either both or one of the premisses must be like the conclusion. I mean not only in being affirmative 30or negative, but also in being necessary, pure, problematic. We must consider also the other forms of predication.
It is clear also when a syllogism in general can be made and when it cannot; and when a valid, when a perfect syllogism can be formed; and that if a syllogism is formed the terms must be arranged 35in one of the ways that have been mentioned.
Book 1,Chapter 25 (41b36–42b26)
Δῆλον δὲ καὶ ὅτι πᾶσα ἀπόδειξις ἔσται διὰ τριῶν ὅρων
καὶ οὐ πλειόνων, ἐὰν μὴ δι' ἄλλων καὶ ἄλλων τὸ αὐτὸ
συμπέρασμα γίνηται, οἷον τὸ Ε διά τε τῶν Α Β καὶ διὰ
τῶν Γ Δ, ἢ διὰ τῶν Α Β καὶ Α Γ Δ· πλείω γὰρ μέσα τῶν
40 αὐτῶν οὐδὲν εἶναι κωλύει. τούτων δ' ὄντων οὐχ εἷς ἀλλὰ
36It is clear too that every demonstration will proceed through three terms and no more, unless the same conclusion is established by different pairs of propositions; e.g. 40the conclusion E may be established through the propositions A and B, and through the propositions C and D, or through the propositions A and B, or A and C, or B and C.
42a
1 πλείους εἰσὶν οἱ συλλογισμοί. ἢ πάλιν ὅταν ἑκάτερον τῶν Α Β
διὰ συλλογισμοῦ ληφθῇ (οἷον τὸ Α διὰ τῶν Δ Ε καὶ πάλιν
τὸ Β διὰ τῶν Ζ Θ), ἢ τὸ μὲν ἐπαγωγῇ, τὸ δὲ συλλογισμῷ.
ἀλλὰ καὶ οὕτως πλείους οἱ συλλογισμοί· πλείω γὰρ
5 τὰ συμπεράσματα ἐστιν, οἷον τό τε Α καὶ τὸ Β καὶ τὸ Γ.
Εἰ δ' οὖν μὴ πλείους ἀλλ' εἷς, οὕτω μὲν ἐνδέχεται γενέσθαι
διὰ πλειόνων τὸ αὐτὸ συμπέρασμα, ὡς δὲ τὸ Γ διὰ τῶν
Α Β, ἀδύνατον. ἔστω γὰρ τὸ Ε συμπεπερασμένον ἐκ τῶν
Α Β Γ Δ. οὐκοῦν ἀνάγκη τι αὐτῶν ἄλλο πρὸς ἄλλο εἰλῆφθαι,
10 τὸ μὲν ὡς ὅλον τὸ δ' ὡς μέρος· τοῦτο γὰρ δέδεικται πρότερον,
ὅτι ὄντος συλλογισμοῦ ἀναγκαῖον οὕτως τινὰς ἔχειν
τῶν ὅρων. ἐχέτω οὖν τὸ Α οὕτως πρὸς τὸ Β. ἔστιν ἄρα τι ἐξ
αὐτῶν συμπέρασμα. οὐκοῦν ἤτοι τὸ Ε ἢ τῶν Γ Δ θάτερον ἢ
ἄλλο τι παρὰ ταῦτα. καὶ εἰ μὲν τὸ Ε, ἐκ τῶν Α Β μόνον
15 ἂν εἴη ὁ συλλογισμός. τὰ δὲ Γ Δ εἰ μὲν ἔχει οὕτως ὥστ'
εἶναι τὸ μὲν ὡς ὅλον τὸ δ' ὡς μέρος, ἔσται τι καὶ ἐξ ἐκείνων,
καὶ ἤτοι τὸ Ε ἢ τῶν Α Β θάτερον ἢ ἄλλο τι παρὰ
ταῦτα. καὶ εἰ μὲν τὸ Ε ἢ τῶν Α Β θάτερον, ἢ πλείους ἔσονται
οἱ συλλογισμοί, ἢ ὡς ἐνεδέχετο ταὐτὸ διὰ πλειόνων
20 ὅρων περαίνεσθαι συμβαίνει· εἰ δ' ἄλλο τι παρὰ ταῦτα,
πλείους ἔσονται καὶ ἀσύναπτοι οἱ συλλογισμοὶ πρὸς ἀλλήλους.
εἰ δὲ μὴ οὕτως ἔχοι τὸ Γ πρὸς τὸ Δ ὥστε ποιεῖν συλλογισμόν,
μάτην ἔσται εἰλημμένα, εἰ μὴ ἐπαγωγῆς ἢ κρύψεως
ἤ τινος ἄλλου τῶν τοιούτων χάριν. Εἰ δ' ἐκ τῶν Α Β
25 μὴ τὸ Ε ἀλλ' ἄλλο τι γίγνεται συμπέρασμα, ἐκ δὲ τῶν
Γ Δ ἢ τούτων θάτερον ἢ ἄλλο παρὰ ταῦτα, πλείους τε οἱ
συλλογισμοὶ γίνονται καὶ οὐ τοῦ ὑποκειμένου· ὑπέκειτο γὰρ
εἶναι τοῦ Ε τὸν συλλογισμόν. εἰ δὲ μὴ γίνεται ἐκ τῶν Γ Δ μηδὲν
συμπέρασμα, μάτην τε εἰλῆφθαι αὐτὰ συμβαίνει καὶ μὴ
30 τοῦ ἐξ ἀρχῆς εἶναι τὸν συλλογισμόν. ὥστε φανερὸν ὅτι πᾶσα
ἀπόδειξις καὶ πᾶς συλλογισμὸς ἔσται διὰ τριῶν ὅρων μόνον.
Τούτου δ' ὄντος φανεροῦ, δῆλον ὡς καὶ ἐκ δύο προτάσεων
καὶ οὐ πλειόνων (οἱ γὰρ τρεῖς ὅροι δύο προτάσεις), εἰ
μὴ προσλαμβάνοιτό τι, καθάπερ ἐν τοῖς ἐξ ἀρχῆς ἐλέχθη,
35 πρὸς τὴν τελείωσιν τῶν συλλογισμῶν. φανερὸν οὖν ὡς ἐν ᾧ
λόγῳ συλλογιστικῷ μὴ ἄρτιαί εἰσιν αἱ προτάσεις δι' ὧν γίνεται
τὸ συμπέρασμα τὸ κύριον (ἔνια γὰρ τῶν ἄνωθεν συμπερασμάτων
ἀναγκαῖον εἶναι προτάσεις), οὗτος ὁ λόγος ἢ
οὐ συλλελόγισται ἢ πλείω τῶν ἀναγκαίων ἠρώτηκε πρὸς τὴν
40 θέσιν.
1For nothing prevents there being several middles for the same terms. But in that case there is not one but several syllogisms. Or again when each of the propositions A and B is obtained by syllogistic inference, e.g. by means of D and E, and again B by means of F and G. Or one may be obtained by syllogistic, the other by inductive inference. But thus also the syllogisms are many; 5for the conclusions are many, e.g. A and B and C. But if this can be called one syllogism, not many, the same conclusion may be reached by more than three terms in this way, but it cannot be reached as C is established by means of A and B. Suppose that the proposition E is inferred from the premisses A, B, C, and D. It is necessary then that of these 10one should be related to another as whole to part: for it has already been proved that if a syllogism is formed some of its terms must be related in this way. Suppose then that A stands in this relation to B. Some conclusion then follows from them. It must either be E or one or other of C and D, or something other than these.
(1) If it is E the syllogism will have A and B for its sole premisses. 15But if C and D are so related that one is whole, the other part, some conclusion will follow from them also; and it must be either E, or one or other of the propositions A and B, or something other than these. And if it is (i) E, or (ii) A or B, either (i) the syllogisms will be more than one, or (ii) the same thing happens to be inferred by means of several terms only in the sense which we saw to be possible. 20But if (iii) the conclusion is other than E or A or B, the syllogisms will be many, and unconnected with one another. But if C is not so related to D as to make a syllogism, the propositions will have been assumed to no purpose, unless for the sake of induction or of obscuring the argument or something of the sort.
(2) But if from the propositions A and B 25there follows not E but some other conclusion, and if from C and D either A or B follows or something else, then there are several syllogisms, and they do not establish the conclusion proposed: for we assumed that the syllogism proved E. And if no conclusion follows from C and D, it turns out that these propositions have been assumed to no purpose, and 30the syllogism does not prove the original proposition.
So it is clear that every demonstration and every syllogism will proceed through three terms only.
This being evident, it is clear that a syllogistic conclusion follows from two premisses and not from more than two. For the three terms make two premisses, unless a new premiss is assumed, as was said at the beginning, 35to perfect the syllogisms. It is clear therefore that in whatever syllogistic argument the premisses through which the main conclusion follows (for some of the preceding conclusions must be premisses) are not even in number, this argument either has not been drawn syllogistically or it has assumed more than was necessary 40to establish its thesis.
(1) If it is E the syllogism will have A and B for its sole premisses. 15But if C and D are so related that one is whole, the other part, some conclusion will follow from them also; and it must be either E, or one or other of the propositions A and B, or something other than these. And if it is (i) E, or (ii) A or B, either (i) the syllogisms will be more than one, or (ii) the same thing happens to be inferred by means of several terms only in the sense which we saw to be possible. 20But if (iii) the conclusion is other than E or A or B, the syllogisms will be many, and unconnected with one another. But if C is not so related to D as to make a syllogism, the propositions will have been assumed to no purpose, unless for the sake of induction or of obscuring the argument or something of the sort.
(2) But if from the propositions A and B 25there follows not E but some other conclusion, and if from C and D either A or B follows or something else, then there are several syllogisms, and they do not establish the conclusion proposed: for we assumed that the syllogism proved E. And if no conclusion follows from C and D, it turns out that these propositions have been assumed to no purpose, and 30the syllogism does not prove the original proposition.
So it is clear that every demonstration and every syllogism will proceed through three terms only.
This being evident, it is clear that a syllogistic conclusion follows from two premisses and not from more than two. For the three terms make two premisses, unless a new premiss is assumed, as was said at the beginning, 35to perfect the syllogisms. It is clear therefore that in whatever syllogistic argument the premisses through which the main conclusion follows (for some of the preceding conclusions must be premisses) are not even in number, this argument either has not been drawn syllogistically or it has assumed more than was necessary 40to establish its thesis.
42b
1 Κατὰ μὲν οὖν τὰς κυρίας προτάσεις λαμβανομένων
τῶν συλλογισμῶν, ἅπας ἔσται συλλογισμὸς ἐκ προτάσεων
μὲν ἀρτίων ἐξ ὅρων δὲ περιττῶν· ἑνὶ γὰρ πλείους οἱ ὅροι τῶν
προτάσεων. ἔσται δὲ καὶ τὰ συμπεράσματα ἡμίση τῶν προτάσεων.
5 ὅταν δὲ διὰ προσυλλογισμῶν περαίνηται ἢ διὰ
πλειόνων μέσων συνεχῶν, οἷον τὸ Α Β διὰ τῶν Γ Δ, τὸ
μὲν πλῆθος τῶν ὅρων ὡσαύτως ἑνὶ ὑπερέξει τὰς προτάσεις
(ἢ γὰρ ἔξωθεν ἢ εἰς τὸ μέσον τεθήσεται ὁ παρεμπίπτων ὅρος·
ἀμφοτέρως δὲ συμβαίνει ἑνὶ ἐλάττω εἶναι τὰ διαστήματα
10 τῶν ὅρων), αἱ δὲ προτάσεις ἴσαι τοῖς διαστήμασιν· οὐ μέντοι
αἰεὶ αἱ μὲν ἄρτιαι ἔσονται οἱ δὲ περιττοί, ἀλλ' ἐναλλάξ,
ὅταν μὲν αἱ προτάσεις ἄρτιαι, περιττοὶ οἱ ὅροι, ὅταν δ' οἱ
ὅροι ἄρτιοι, περιτταὶ αἱ προτάσεις· ἅμα γὰρ τῷ ὅρῳ μία
προστίθεται πρότασις, ἂν ὁποθενοῦν προστεθῇ ὁ ὅρος, ὥστ' ἐπεὶ
15 αἱ μὲν ἄρτιαι οἱ δὲ περιττοὶ ἦσαν, ἀνάγκη παραλλάττειν
τῆς αὐτῆς προσθέσεως γινομένης. τὰ δὲ συμπεράσματα οὐκέτι
τὴν αὐτὴν ἕξει τάξιν οὔτε πρὸς τοὺς ὅρους οὔτε πρὸς τὰς προτάσεις·
ἑνὸς γὰρ ὅρου προστιθεμένου συμπεράσματα προςτεθήσεται
ἑνὶ ἐλάττω τῶν προϋπαρχόντων ὅρων· πρὸς μόνον
20 γὰρ τὸν ἔσχατον οὐ ποιεῖ συμπέρασμα, πρὸς δὲ τοὺς ἄλλους
πάντας, οἷον εἰ τῷ Α Β Γ πρόσκειται τὸ Δ, εὐθὺς καὶ
συμπεράσματα δύο πρόσκειται, τό τε πρὸς τὸ Α καὶ τὸ πρὸς
τὸ Β. ὁμοίως δὲ κἀπὶ τῶν ἄλλων. κἂν εἰς τὸ μέσον δὲ παρεμπίπτῃ,
τὸν αὐτὸν τρόπον· πρὸς ἕνα γὰρ μόνον οὐ ποιήσει
25 συλλογισμόν. ὥστε πολὺ πλείω τὰ συμπεράσματα καὶ τῶν
ὅρων ἔσται καὶ τῶν προτάσεων.
1If then syllogisms are taken with respect to their main premisses, every syllogism will consist of an even number of premisses and an odd number of terms (for the terms exceed the premisses by one), and the conclusions will be half the number of the premisses. 5But whenever a conclusion is reached by means of prosyllogisms or by means of several continuous middle terms, e.g. the proposition AB by means of the middle terms C and D, the number of the terms will similarly exceed that of the premisses by one (for the extra term must either be added outside or inserted: but in either case it follows that the relations of predication are one fewer than the terms related), and 10the premisses will be equal in number to the relations of predication. The premisses however will not always be even, the terms odd; but they will alternate-when the premisses are even, the terms must be odd; when the terms are even, the premisses must be odd: for along with one term one premiss is added, if a term is added from any quarter. Consequently 15since the premisses were (as we saw) even, and the terms odd, we must make them alternately even and odd at each addition. But the conclusions will not follow the same arrangement either in respect to the terms or to the premisses. For if one term is added, conclusions will be added less by one than the pre-existing terms: for 20the conclusion is drawn not in relation to the single term last added, but in relation to all the rest, e.g. if to ABC the term D is added, two conclusions are thereby added, one in relation to A, the other in relation to B. Similarly with any further additions. And similarly too if the term is inserted in the middle: for in relation to one term only, 25a syllogism will not be constructed. Consequently the conclusions will be much more numerous than the terms or the premisses.
Book 1,Chapter 26 (42b27–43a19)
Ἐπεὶ δ' ἔχομεν περὶ ὧν οἱ συλλογισμοί, καὶ ποῖον ἐν
ἑκάστῳ σχήματι καὶ ποσαχῶς δείκνυται, φανερὸν ἡμῖν ἐστὶ
καὶ ποῖον πρόβλημα χαλεπὸν καὶ ποῖον εὐεπιχείρητον· τὸ
30 μὲν γὰρ ἐν πλείοσι σχήμασι καὶ διὰ πλειόνων πτώσεων περαινόμενον
ῥᾷον, τὸ δ' ἐν ἐλάττοσι καὶ δι' ἐλαττόνων δυςεπιχειρητότερον.
τὸ μὲν οὖν καταφατικὸν τὸ καθόλου διὰ τοῦ
πρώτου σχήματος δείκνυται μόνου, καὶ διὰ τούτου μοναχῶς·
τὸ δὲ στερητικὸν διά τε τοῦ πρώτου καὶ διὰ τοῦ μέσου, καὶ
35 διὰ μὲν τοῦ πρώτου μοναχῶς, διὰ δὲ τοῦ μέσου διχῶς· τὸ
δ' ἐν μέρει καταφατικὸν διὰ τοῦ πρώτου καὶ διὰ τοῦ ἐσχάτου,
μοναχῶς μὲν διὰ τοῦ πρώτου, τριχῶς δὲ διὰ τοῦ ἐσχάτου.
τὸ δὲ στερητικὸν τὸ κατὰ μέρος ἐν ἅπασι τοῖς σχήμασι
δείκνυται, πλὴν ἐν μὲν τῷ πρώτῳ μοναχῶς, ἐν δὲ τῷ μέσῳ
40 καὶ τῷ ἐσχάτῳ ἐν τῷ μὲν διχῶς ἐν τῷ δὲ τριχῶς. φανερὸν
27Since we understand the subjects with which syllogisms are concerned, what sort of conclusion is established in each figure, and in how many moods this is done, it is evident to us both what sort of problem is difficult and what sort is easy to prove. 30For that which is concluded in many figures and through many moods is easier; that which is concluded in few figures and through few moods is more difficult to attempt. The universal affirmative is proved by means of the first figure only and by this in only one mood; the universal negative is proved both through the first figure and through the second, 35through the first in one mood, through the second in two. The particular affirmative is proved through the first and through the last figure, in one mood through the first, in three moods through the last. The particular negative is proved in all the figures, but once in the first, in two moods in the second, 40in three moods in the third. It is clear then that the universal affirmative is most difficult to establish, most easy to overthrow.
43a
1 οὖν ὅτι τὸ καθόλου κατηγορικὸν κατασκευάσαι μὲν χαλεπώτατον,
ἀνασκευάσαι δὲ ῥᾷστον. ὅλως δ' ἐστὶν ἀναιροῦντι
μὲν τὰ καθόλου τῶν ἐν μέρει ῥᾴω· καὶ γὰρ ἢν μηδενὶ καὶ
ἢν τινὶ μὴ ὑπάρχῃ, ἀνῄρηται· τούτων δὲ τὸ μὲν τινὶ μὴ ἐν
5 ἅπασι τοῖς σχήμασι δείκνυται, τὸ δὲ μηδενὶ ἐν τοῖς δυσίν.
τὸν αὐτὸν δὲ τρόπον κἀπὶ τῶν στερητικῶν· καὶ γὰρ εἰ παντὶ
καὶ εἰ τινί, ἀνῄρηται τὸ ἐξ ἀρχῆς· τοῦτο δ' ἦν ἐν δύο σχήμασιν.
ἐπὶ δὲ τῶν ἐν μέρει μοναχῶς, ἢ παντὶ ἢ μηδενὶ δείξαντα
ὑπάρχειν. κατασκευάζοντι δὲ ῥᾴω τὰ ἐν μέρει· καὶ
10 γὰρ ἐν πλείοσι σχήμασι καὶ διὰ πλειόνων τρόπων. ὅλως τε
οὐ δεῖ λανθάνειν ὅτι ἀνασκευάσαι μὲν δι' ἀλλήλων ἔστι καὶ
τὰ καθόλου διὰ τῶν ἐν μέρει καὶ ταῦτα διὰ τῶν καθόλου,
κατασκευάσαι δ' οὐκ ἔστι διὰ τῶν κατὰ μέρος τὰ καθόλου,
δι' ἐκείνων δὲ ταῦτ' ἔστιν. ἅμα δὲ δῆλον ὅτι καὶ τὸ ἀνασκευάζειν
15 ἐστὶ τοῦ κατασκευάζειν ῥᾷον.
Πῶς μὲν οὖν γίνεται πᾶς συλλογισμὸς καὶ διὰ πόσων
ὅρων καὶ προτάσεων, καὶ πῶς ἐχουσῶν πρὸς ἀλλήλας, ἔτι
δὲ ποῖον πρόβλημα ἐν ἑκάστῳ σχήματι καὶ ποῖον ἐν πλείοσι
καὶ ποῖον ἐν ἐλάττοσι δείκνυται, δῆλον ἐκ τῶν εἰρημένων.
1In general, universals are easier game for the destroyer than particulars: for whether the predicate belongs to none or not to some, they are destroyed: and 5the particular negative is proved in all the figures, the universal negative in two. Similarly with universal negatives: the original statement is destroyed, whether the predicate belongs to all or to some: and this we found possible in two figures. But particular statements can be refuted in one way only-by proving that the predicate belongs either to all or to none. But particular statements are easier to establish: 10for proof is possible in more figures and through more moods. And in general we must not forget that it is possible to refute statements by means of one another, I mean, universal statements by means of particular, and particular statements by means of universal: but it is not possible to establish universal statements by means of particular, though it is possible to establish particular statements by means of universal. 15At the same time it is evident that it is easier to refute than to establish.
The manner in which every syllogism is produced, the number of the terms and premisses through which it proceeds, the relation of the premisses to one another, the character of the problem proved in each figure, and the number of the figures appropriate to each problem, all these matters are clear from what has been said.
The manner in which every syllogism is produced, the number of the terms and premisses through which it proceeds, the relation of the premisses to one another, the character of the problem proved in each figure, and the number of the figures appropriate to each problem, all these matters are clear from what has been said.
Book 1,Chapter 27 (43a20–43b38)
20 πῶς δ' εὐπορήσομεν αὐτοὶ πρὸς τὸ τιθέμενον ἀεὶ συλλογισμῶν,
καὶ διὰ ποίας ὁδοῦ ληψόμεθα τὰς περὶ ἕκαστον ἀρχάς,
νῦν ἤδη λεκτέον· οὐ γὰρ μόνον ἴσως δεῖ τὴν γένεσιν
θεωρεῖν τῶν συλλογισμῶν, ἀλλὰ καὶ τὴν δύναμιν ἔχειν τοῦ
ποιεῖν.
25 Ἁπάντων δὴ τῶν ὄντων τὰ μέν ἐστι τοιαῦτα ὥστε κατὰ
μηδενὸς ἄλλου κατηγορεῖσθαι ἀληθῶς καθόλου (οἷον Κλέων
καὶ Καλλίας καὶ τὸ καθ' ἕκαστον καὶ αἰσθητόν), κατὰ δὲ
τούτων ἄλλα (καὶ γὰρ ἄνθρωπος καὶ ζῷον ἑκάτερος τούτων
ἐστί)· τὰ δ' αὐτὰ μὲν κατ' ἄλλων κατηγορεῖται, κατὰ δὲ
30 τούτων ἄλλα πρότερον οὐ κατηγορεῖται· τὰ δὲ καὶ αὐτὰ ἄλλων
καὶ αὐτῶν ἕτερα, οἷον ἄνθρωπος Καλλίου καὶ ἀνθρώπου
ζῷον. ὅτι μὲν οὖν ἔνια τῶν ὄντων κατ' οὐδενὸς πέφυκε λέγεσθαι,
δῆλον· τῶν γὰρ αἰσθητῶν σχεδὸν ἕκαστόν ἐστι τοιοῦτον
ὥστε μὴ κατηγορεῖσθαι κατὰ μηδενός, πλὴν ὡς κατὰ συμβεβηκός·
35 φαμὲν γάρ ποτε τὸ λευκὸν ἐκεῖνο Σωκράτην εἶναι
καὶ τὸ προσιὸν Καλλίαν. ὅτι δὲ καὶ ἐπὶ τὸ ἄνω πορευομένοις
ἵσταταί ποτε, πάλιν ἐροῦμεν· νῦν δ' ἔστω τοῦτο κείμενον. κατὰ
μὲν οὖν τούτων οὐκ ἔστιν ἀποδεῖξαι κατηγορούμενον ἕτερον,
πλὴν εἰ μὴ κατὰ δόξαν, ἀλλὰ ταῦτα κατ' ἄλλων· οὐδὲ τὰ
40 καθ' ἕκαστα κατ' ἄλλων, ἀλλ' ἕτερα κατ' ἐκείνων. τὰ δὲ
μεταξὺ δῆλον ὡς ἀμφοτέρως ἐνδέχεται (καὶ γὰρ αὐτὰ κατ'
ἄλλων καὶ ἄλλα κατὰ τούτων λεχθήσεται)· καὶ σχεδὸν οἱ
λόγοι καὶ αἱ σκέψεις εἰσὶ μάλιστα περὶ τούτων.
20We must now state how we may ourselves always have a supply of syllogisms in reference to the problem proposed and by what road we may reach the principles relative to the problem: for perhaps we ought not only to investigate the construction of syllogisms, but also to have the power of making them.
25Of all the things which exist some are such that they cannot be predicated of anything else truly and universally, e.g. Cleon and Callias, i.e. the individual and sensible, but other things may be predicated of them (for each of these is both man and animal); 30and some things are themselves predicated of others, but nothing prior is predicated of them; and some are predicated of others, and yet others of them, e.g. man of Callias and animal of man. It is clear then that some things are naturally not stated of anything: for as a rule each sensible thing is such that it cannot be predicated of anything, save incidentally: 35for we sometimes say that that white object is Socrates, or that that which approaches is Callias. We shall explain in another place that there is an upward limit also to the process of predicating: for the present we must assume this. Of these ultimate predicates it is not possible to demonstrate another predicate, save as a matter of opinion, but these may be predicated of other things. 40Neither can individuals be predicated of other things, though other things can be predicated of them. Whatever lies between these limits can be spoken of in both ways: they may be stated of others, and others stated of them. And as a rule arguments and inquiries are concerned with these things. We must select the premisses suitable to each problem in this manner: first we must lay down the subject and the definitions and the properties of the thing; next we must lay down those attributes which follow the thing, and again those which the thing follows, and those which cannot belong to it.
25Of all the things which exist some are such that they cannot be predicated of anything else truly and universally, e.g. Cleon and Callias, i.e. the individual and sensible, but other things may be predicated of them (for each of these is both man and animal); 30and some things are themselves predicated of others, but nothing prior is predicated of them; and some are predicated of others, and yet others of them, e.g. man of Callias and animal of man. It is clear then that some things are naturally not stated of anything: for as a rule each sensible thing is such that it cannot be predicated of anything, save incidentally: 35for we sometimes say that that white object is Socrates, or that that which approaches is Callias. We shall explain in another place that there is an upward limit also to the process of predicating: for the present we must assume this. Of these ultimate predicates it is not possible to demonstrate another predicate, save as a matter of opinion, but these may be predicated of other things. 40Neither can individuals be predicated of other things, though other things can be predicated of them. Whatever lies between these limits can be spoken of in both ways: they may be stated of others, and others stated of them. And as a rule arguments and inquiries are concerned with these things. We must select the premisses suitable to each problem in this manner: first we must lay down the subject and the definitions and the properties of the thing; next we must lay down those attributes which follow the thing, and again those which the thing follows, and those which cannot belong to it.
43b
1 Δεῖ δὴ τὰς προτάσεις περὶ ἕκαστον οὕτως ἐκλαμβάνειν,
ὑποθέμενον αὐτὸ πρῶτον καὶ τοὺς ὁρισμούς τε καὶ ὅσα ἴδια
τοῦ πράγματός ἐστιν, εἶτα μετὰ τοῦτο ὅσα ἕπεται τῷ πράγματι,
καὶ πάλιν οἷς τὸ πρᾶγμα ἀκολουθεῖ, καὶ ὅσα μὴ
5 ἐνδέχεται αὐτῷ ὑπάρχειν. οἷς δ' αὐτὸ μὴ ἐνδέχεται, οὐκ
ἐκληπτέον διὰ τὸ ἀντιστρέφειν τὸ στερητικόν. διαιρετέον δὲ καὶ
τῶν ἑπομένων ὅσα τε ἐν τῷ τί ἐστι καὶ ὅσα ἴδια καὶ ὅσα
ὡς συμβεβηκότα κατηγορεῖται, καὶ τούτων ποῖα δοξαστικῶς
καὶ ποῖα κατ' ἀλήθειαν· ὅσῳ μὲν γὰρ ἂν πλειόνων τοιούτων
10 εὐπορῇ τις, θᾶττον ἐντεύξεται συμπεράσματι, ὅσῳ δ' ἂν
ἀληθεστέρων, μᾶλλον ἀποδείξει. Δεῖ δ' ἐκλέγειν μὴ τὰ ἑπόμενα
τινί, ἀλλ' ὅσα ὅλῳ τῷ πράγματι ἕπεται, οἷον μὴ τί
τινὶ ἀνθρώπῳ ἀλλὰ τί παντὶ ἀνθρώπῳ ἕπεται· διὰ γὰρ τῶν
καθόλου προτάσεων ὁ συλλογισμός. ἀδιορίστου μὲν οὖν ὄντος
15 ἄδηλον εἰ καθόλου ἡ πρότασις, διωρισμένου δὲ φανερόν.
ὁμοίως δ' ἐκλεκτέον καὶ οἷς αὐτὸ ἕπεται ὅλοις, διὰ τὴν εἰρημένην
αἰτίαν. αὐτὸ δὲ τὸ ἑπόμενον οὐ ληπτέον ὅλον ἕπεσθαι,
λέγω δ' οἷον ἀνθρώπῳ πᾶν ζῷον ἢ μουσικῇ πᾶσαν ἐπιστήμην,
ἀλλὰ μόνον ἁπλῶς ἀκολουθεῖν, καθάπερ καὶ προτεινόμεθα·
20 καὶ γὰρ ἄχρηστον θάτερον καὶ ἀδύνατον, οἷον
πάντα ἄνθρωπον εἶναι πᾶν ζῷον ἢ δικαιοσύνην ἅπαν ἀγαθόν.
ἀλλ' ᾧ ἕπεται, ἐπ' ἐκείνου τὸ παντὶ λέγεται. ὅταν δ' ὑπό
τινος περιέχηται τὸ ὑποκείμενον ᾧ τὰ ἑπόμενα δεῖ λαβεῖν,
τὰ μὲν τῷ καθόλου ἑπόμενα ἢ μὴ ἑπόμενα οὐκ ἐκλεκτέον ἐν
25 τούτοις (εἴληπται γὰρ ἐν ἐκείνοις· ὅσα γὰρ ζῴῳ, καὶ ἀνθρώπῳ
ἕπεται, καὶ ὅσα μὴ ὑπάρχει, ὡσαύτως), τὰ δὲ
περὶ ἕκαστον ἴδια ληπτέον· ἔστι γὰρ ἄττα τῷ εἴδει ἴδια παρὰ
τὸ γένος· ἀνάγκη γὰρ τοῖς ἑτέροις εἴδεσιν ἴδια ἄττα ὑπάρχειν.
οὐδὲ δὴ τῷ καθόλου ἐκλεκτέον οἷς ἕπεται τὸ περιεχόμενον,
30 οἷον ζῴῳ οἷς ἕπεται ἄνθρωπος· ἀνάγκη γάρ, εἰ
ἀνθρώπῳ ἀκολουθεῖ τὸ ζῷον, καὶ τούτοις ἅπασιν ἀκολουθεῖν,
οἰκειότερα δὲ ταῦτα τῆς τοῦ ἀνθρώπου ἐκλογῆς. ληπτέον δὲ
καὶ τὰ ὡς ἐπὶ τὸ πολὺ ἑπόμενα καὶ οἷς ἕπεται· τῶν
γὰρ ὡς ἐπὶ τὸ πολὺ προβλημάτων καὶ ὁ συλλογισμὸς
35 ἐκ τῶν ὡς ἐπὶ τὸ πολὺ προτάσεων, ἢ πασῶν ἢ τινῶν· ὅμοιον
γὰρ ἑκάστου τὸ συμπέρασμα ταῖς ἀρχαῖς. ἔτι τὰ πᾶσιν
ἑπόμενα οὐκ ἐκλεκτέον· οὐ γὰρ ἔσται συλλογισμὸς ἐξ αὐτῶν.
δι' ἣν δ' αἰτίαν, ἐν τοῖς ἑπομένοις ἔσται δῆλον.
1But those to which it cannot belong need not be selected, because the negative statement implied above is convertible. Of the attributes which follow we must distinguish those which fall within the definition, those which are predicated as properties, and those which are predicated as accidents, and of the latter those which apparently and those which really belong. The larger the supply a man has of these, 10the more quickly will he reach a conclusion; and in proportion as he apprehends those which are truer, the more cogently will he demonstrate. But he must select not those which follow some particular but those which follow the thing as a whole, e.g. not what follows a particular man but what follows every man: for the syllogism proceeds through universal premisses. If the statement is indefinite, 15it is uncertain whether the premiss is universal, but if the statement is definite, the matter is clear. Similarly one must select those attributes which the subject follows as wholes, for the reason given. But that which follows one must not suppose to follow as a whole, e.g. that every animal follows man or every science music, but only that it follows, without qualification, and indeed we state it in a proposition: 20for the other statement is useless and impossible, e.g. that every man is every animal or justice is all good. But that which something follows receives the mark 'every'. Whenever the subject, for which we must obtain the attributes that follow, is contained by something else, what follows or does not follow the highest term universally must not be selected in dealing with the subordinate term (25for these attributes have been taken in dealing with the superior term; for what follows animal also follows man, and what does not belong to animal does not belong to man); but we must choose those attributes which are peculiar to each subject. For some things are peculiar to the species as distinct from the genus; for species being distinct there must be attributes peculiar to each. Nor must we take as things which the superior term follows, those things which the inferior term follows, e.g. take as subjects of the predicate 'animal' what are really subjects of the predicate 'man'. 30It is necessary indeed, if animal follows man, that it should follow all these also. But these belong more properly to the choice of what concerns man. One must apprehend also normal consequents and normal antecedents-, for propositions which obtain normally are established syllogistically 35from premisses which obtain normally, some if not all of them having this character of normality. For the conclusion of each syllogism resembles its principles. We must not however choose attributes which are consequent upon all the terms: for no syllogism can be made out of such premisses. The reason why this is so will be clear in the sequel.
Book 1,Chapter 28 (43b39–45a22)
Κατασκευάζειν μὲν οὖν βουλομένοις κατά τινος ὅλου
40 τοῦ μὲν κατασκευαζομένου βλεπτέον εἰς τὰ ὑποκείμενα καθ'
ὧν αὐτὸ τυγχάνει λεγόμενον, οὗ δὲ δεῖ κατηγορεῖσθαι, ὅσα
τούτῳ ἕπεται· ἂν γάρ τι τούτων ᾖ ταὐτόν, ἀνάγκη θάτερον
θατέρῳ ὑπάρχειν. ἢν δὲ μὴ ὅτι παντὶ ἀλλ' ὅτι τινί, οἷς ἕπεται
39If men wish to establish something about some whole, 40they must look to the subjects of that which is being established (the subjects of which it happens to be asserted), and the attributes which follow that of which it is to be predicated. For if any of these subjects is the same as any of these attributes, the attribute originally in question must belong to the subject originally in question.
44a
1 ἑκάτερον· εἰ γάρ τι τούτων ταὐτόν, ἀνάγκη τινὶ ὑπάρχειν.
ὅταν δὲ μηδενὶ δέῃ ὑπάρχειν, ᾧ μὲν οὐ δεῖ ὑπάρχειν,
εἰς τὰ ἑπόμενα, ὃ δὲ δεῖ μὴ ὑπάρχειν, εἰς ἃ μὴ ἐνδέχεται
αὐτῷ παρεῖναι· ἢ ἀνάπαλιν, ᾧ μὲν δεῖ μὴ ὑπάρχειν, εἰς ἃ
5 μὴ ἐνδέχεται αὐτῷ παρεῖναι, ὃ δὲ μὴ ὑπάρχειν, εἰς τὰ
ἑπόμενα. τούτων γὰρ ὄντων τῶν αὐτῶν ὁποτερωνοῦν, οὐδενὶ
ἐνδέχεται θατέρῳ θάτερον ὑπάρχειν· γίνεται γὰρ ὁτὲ μὲν ὁ
ἐν τῷ πρώτῳ σχήματι συλλογισμός, ὁτὲ δ' ὁ ἐν τῷ μέσῳ.
ἐὰν δὲ τινὶ μὴ ὑπάρχειν, ᾧ μὲν δεῖ μὴ ὑπάρχειν, οἷς ἕπεται,
10 ὃ δὲ μὴ ὑπάρχειν, ἃ μὴ δυνατὸν αὐτῷ ὑπάρχειν· εἰ γάρ
τι τούτων εἴη ταὐτόν, ἀνάγκη τινὶ μὴ ὑπάρχειν. Μᾶλλον δ'
ἴσως ὧδ' ἔσται τῶν λεγομένων ἕκαστον φανερόν. ἔστω γὰρ τὰ
μὲν ἑπόμενα τῷ Α ἐφ' ὧν Β, οἷς δ' αὐτὸ ἕπεται, ἐφ' ὧν
Γ, ἃ δὲ μὴ ἐνδέχεται αὐτῷ ὑπάρχειν, ἐφ' ὧν Δ· πάλιν
15 δὲ τῷ Ε τὰ μὲν ὑπάρχοντα, ἐφ' οἷς Ζ, οἷς δ' αὐτὸ ἕπεται,
ἐφ' οἷς Η, ἃ δὲ μὴ ἐνδέχεται αὐτῷ ὑπάρχειν, ἐφ'
οἷς Θ. εἰ μὲν οὖν ταὐτό τί ἐστι τῶν Γ τινὶ τῶν Ζ, ἀνάγκη
τὸ Α παντὶ τῷ Ε ὑπάρχειν· τὸ μὲν γὰρ Ζ παντὶ τῷ Ε, τῷ
δὲ Γ παντὶ τὸ Α, ὥστε παντὶ τῷ Ε τὸ Α. εἰ δὲ τὸ Γ καὶ
20 τὸ Η ταὐτόν, ἀνάγκη τινὶ τῷ Ε τὸ Α ὑπάρχειν· τῷ μὲν
γὰρ Γ τὸ Α, τῷ δὲ Η τὸ Ε παντὶ ἀκολουθεῖ. εἰ δὲ τὸ Ζ
καὶ τὸ Δ ταὐτόν, οὐδενὶ τῶν Ε τὸ Α ὑπάρξει ἐκ προσυλλογισμοῦ·
ἐπεὶ γὰρ ἀντιστρέφει τὸ στερητικὸν καὶ τὸ Ζ τῷ Δ
ταὐτόν, οὐδενὶ τῶν Ζ ὑπάρξει τὸ Α, τὸ δὲ Ζ παντὶ τῷ Ε.
25 πάλιν εἰ τὸ Β καὶ τὸ Θ ταὐτόν, οὐδενὶ τῶν Ε τὸ Α ὑπάρξει·
τὸ γὰρ Β τῷ μὲν Α παντί, τῷ δ' ἐφ' ᾧ τὸ Ε οὐδενὶ ὑπάρξει·
ταὐτὸ γὰρ ἦν τῷ Θ, τὸ δὲ Θ οὐδενὶ τῶν Ε ὑπῆρχεν.
εἰ δὲ τὸ Δ καὶ τὸ Η ταὐτόν, τὸ Α τινὶ τῷ Ε οὐχ ὑπάρξει·
τῷ γὰρ Η οὐχ ὑπάρξει, ὅτι οὐδὲ τῷ Δ· τὸ δὲ Η ἐστὶν ὑπὸ
30 τὸ Ε, ὥστε τινὶ τῶν Ε οὐχ ὑπάρξει. εἰ δὲ τῷ Η τὸ Β ταὐτόν,
ἀντεστραμμένος ἔσται συλλογισμός· τὸ μὲν γὰρ Ε τῷ
Α ὑπάρξει παντί—τὸ γὰρ Β τῷ Α, τὸ δὲ Ε τῷ Β (ταὐτὸ
γὰρ ἦν τῷ Η)—τὸ δὲ Α τῷ Ε παντὶ μὲν οὐκ ἀνάγκη ὑπάρχειν,
τινὶ δ' ἀνάγκη διὰ τὸ ἀντιστρέφειν τὴν καθόλου κατηγορίαν
35 τῇ κατὰ μέρος.
Φανερὸν οὖν ὅτι εἰς τὰ προειρημένα βλεπτέον ἑκατέρου
καθ' ἕκαστον πρόβλημα· διὰ τούτων γὰρ ἅπαντες οἱ συλλογισμοί.
δεῖ δὲ καὶ τῶν ἑπομένων, καὶ οἷς ἕπεται ἕκαστον,
εἰς τὰ πρῶτα καὶ τὰ καθόλου μάλιστα βλέπειν, οἷον τοῦ
40 μὲν Ε μᾶλλον εἰς τὸ Κ Ζ ἢ εἰς τὸ Ζ μόνον, τοῦ δὲ Α εἰς
1But if the purpose is to establish not a universal but a particular proposition, they must look for the terms of which the terms in question are predicable: for if any of these are identical, the attribute in question must belong to some of the subject in question. Whenever the one term has to belong to none of the other, one must look to the consequents of the subject, and to those attributes which cannot possibly be present in the predicate in question: or conversely 5to the attributes which cannot possibly be present in the subject, and to the consequents of the predicate. If any members of these groups are identical, one of the terms in question cannot possibly belong to any of the other. For sometimes a syllogism in the first figure results, sometimes a syllogism in the second. But if the object is to establish a particular negative proposition, we must find antecedents of the subject in question 10and attributes which cannot possibly belong to the predicate in question. If any members of these two groups are identical, it follows that one of the terms in question does not belong to some of the other. Perhaps each of these statements will become clearer in the following way. Suppose the consequents of A are designated by B, the antecedents of A by C, attributes which cannot possibly belong to A by D. Suppose again that 15the attributes of E are designated by F, the antecedents of E by G, and attributes which cannot belong to E by H. If then one of the Cs should be identical with one of the Fs, A must belong to all E: for F belongs to all E, and A to all C, consequently A belongs to all E. 20If C and G are identical, A must belong to some of the Es: for A follows C, and E follows all G. If F and D are identical, A will belong to none of the Es by a prosyllogism: for since the negative proposition is convertible, and F is identical with D, A will belong to none of the Fs, but F belongs to all E. 25Again, if B and H are identical, A will belong to none of the Es: for B will belong to all A, but to no E: for it was assumed to be identical with H, and H belonged to none of the Es. If D and G are identical, A will not belong to some of the Es: for it will not belong to G, because it does not belong to D: 30but G falls under E: consequently A will not belong to some of the Es. If B is identical with G, there will be a converted syllogism: for E will belong to all A since B belongs to A and E to B (for 35B was found to be identical with G): but that A should belong to all E is not necessary, but it must belong to some E because it is possible to convert the universal statement into a particular.
40It is clear then that in every proposition which requires proof we must look to the aforesaid relations of the subject and predicate in question: for all syllogisms proceed through these.
40It is clear then that in every proposition which requires proof we must look to the aforesaid relations of the subject and predicate in question: for all syllogisms proceed through these.
44b
1 τὸ Κ Γ ἢ εἰς τὸ Γ μόνον. εἰ μὲν γὰρ τῷ Κ Ζ ὑπάρχει τὸ
Α, καὶ τῷ Ζ καὶ τῷ Ε ὑπάρχει· εἰ δὲ τούτῳ μὴ ἕπεται,
ἐγχωρεῖ τῷ Ζ ἕπεσθαι. ὁμοίως δὲ καὶ ἐφ' ὧν αὐτὸ ἀκολουθεῖ
σκεπτέον· εἰ μὲν γὰρ τοῖς πρώτοις, καὶ τοῖς ὑπ' ἐκεῖνα
5 ἕπεται, εἰ δὲ μὴ τούτοις, ἀλλὰ τοῖς ὑπὸ ταῦτα ἐγχωρεῖ.
Δῆλον δὲ καὶ ὅτι διὰ τῶν τριῶν ὅρων καὶ τῶν δύο προτάσεων
ἡ σκέψις, καὶ διὰ τῶν προειρημένων σχημάτων οἱ
συλλογισμοὶ πάντες. δείκνυται γὰρ ὑπάρχειν μὲν παντὶ τῷ
Ε τὸ Α, ὅταν τῶν Γ καὶ Ζ ταὐτόν τι ληφθῇ. τοῦτο δ' ἔσται
10 μέσον, ἄκρα δὲ τὸ Α καὶ Ε· γίνεται οὖν τὸ πρῶτον σχῆμα.
τινὶ δέ, ὅταν τὸ Γ καὶ τὸ Η ληφθῇ ταὐτόν. τοῦτο δὲ τὸ ἔσχατον
σχῆμα· μέσον γὰρ τὸ Η γίνεται. μηδενὶ δέ, ὅταν τὸ Δ
καὶ Ζ ταὐτόν. οὕτω δὲ καὶ τὸ πρῶτον σχῆμα καὶ τὸ μέσον,
τὸ μὲν πρῶτον ὅτι οὐδενὶ τῷ Ζ ὑπάρχει τὸ Α (εἴπερ ἀντιστρέφει
15 τὸ στερητικόν), τὸ δὲ Ζ παντὶ τῷ Ε, τὸ δὲ μέσον
ὅτι τὸ Δ τῷ μὲν Α οὐδενὶ τῷ δὲ Ε παντὶ ὑπάρχει. τινὶ δὲ μὴ
ὑπάρχειν, ὅταν τὸ Δ καὶ Η ταὐτὸν ᾖ. τοῦτο δὲ τὸ ἔσχατον
σχῆμα· τὸ μὲν γὰρ Α οὐδενὶ τῷ Η ὑπάρξει, τὸ δὲ
Ε παντὶ τῷ Η. φανερὸν οὖν ὅτι διὰ τῶν προειρημένων σχημάτων
20 οἱ συλλογισμοὶ πάντες, καὶ ὅτι οὐκ ἐκλεκτέον ὅσα
πᾶσιν ἕπεται, διὰ τὸ μηδένα γίγνεσθαι συλλογισμὸν ἐξ αὐτῶν.
κατασκευάζειν μὲν γὰρ ὅλως οὐκ ἦν ἐκ τῶν ἑπομένων,
ἀποστερεῖν δ' οὐκ ἐνδέχεται διὰ τοῦ πᾶσιν ἑπομένου·
δεῖ γὰρ τῷ μὲν ὑπάρχειν τῷ δὲ μὴ ὑπάρχειν.
25 Φανερὸν δὲ καὶ ὅτι αἱ ἄλλαι σκέψεις τῶν κατὰ τὰς
ἐκλογὰς ἄχρειοι πρὸς τὸ ποιεῖν συλλογισμόν, οἷον εἰ τὰ
ἑπόμενα ἑκατέρῳ ταὐτά ἐστιν, ἢ εἰ οἷς ἕπεται τὸ Α καὶ
ἃ μὴ ἐνδέχεται τῷ Ε, ἢ ὅσα πάλιν μὴ ἐγχωρεῖ ἑκατέρῳ
ὑπάρχειν· οὐ γὰρ γίνεται συλλογισμὸς διὰ τούτων. εἰ μὲν
30 γὰρ τὰ ἑπόμενα ταὐτά, οἷον τὸ Β καὶ τὸ Ζ, τὸ μέσον
γίνεται σχῆμα κατηγορικὰς ἔχον τὰς προτάσεις· εἰ δ' οἷς
ἕπεται τὸ Α καὶ ἃ μὴ ἐνδέχεται τῷ Ε, οἷον τὸ Γ καὶ
τὸ Θ, τὸ πρῶτον σχῆμα στερητικὴν ἔχον τὴν πρὸς τὸ ἔλαττον
ἄκρον πρότασιν. εἰ δ' ὅσα μὴ ἐνδέχεται ἑκατέρῳ, οἷον
35 τὸ Δ καὶ τὸ Θ, στερητικαὶ ἀμφότεραι αἱ προτάσεις, ἢ ἐν
τῷ πρώτῳ ἢ ἐν τῷ μέσῳ σχήματι. οὕτως δ' οὐδαμῶς συλλογισμός.
Δῆλον δὲ καὶ ὅτι ὁποῖα ταὐτὰ ληπτέον τὰ κατὰ τὴν
ἐπίσκεψιν, καὶ οὐχ ὁποῖα ἕτερα ἢ ἐναντία, πρῶτον μὲν
40 ὅτι τοῦ μέσου χάριν ἡ ἐπίβλεψις, τὸ δὲ μέσον οὐχ ἕτερον
1But if we are seeking consequents and antecedents we must look for those which are primary and most universal, e.g. in reference to E we must look to Kf rather than to F alone, and in reference to A we must look to KC rather than to C alone. For if A belongs to KF, it belongs both to F and to E: but if it does not follow KF, it may yet follow F. Similarly we must consider the antecedents of A itself: for if a term follows the primary antecedents, it will follow those also which are subordinate, 5but if it does not follow the former, it may yet follow the latter.
It is clear too that the inquiry proceeds through the three terms and the two premisses, and that all the syllogisms proceed through the aforesaid figures. For it is proved that A belongs to all E, whenever an identical term is found among the Cs and Fs. 10This will be the middle term; A and E will be the extremes. So the first figure is formed. And A will belong to some E, whenever C and G are apprehended to be the same. This is the last figure: for G becomes the middle term. And A will belong to no E, when D and F are identical. Thus we have both the first figure and the middle figure; the first, because A belongs to no F, since the negative statement is convertible, 15and F belongs to all E: the middle figure because D belongs to no A, and to all E. And A will not belong to some E, whenever D and G are identical. This is the last figure: for A will belong to no G, and E will belong to all G. Clearly then 20all syllogisms proceed through the aforesaid figures, and we must not select consequents of all the terms, because no syllogism is produced from them. For (as we saw) it is not possible at all to establish a proposition from consequents, and it is not possible to refute by means of a consequent of both the terms in question: for the middle term must belong to the one, and not belong to the other.
25It is clear too that other methods of inquiry by selection of middle terms are useless to produce a syllogism, e.g. if the consequents of the terms in question are identical, or if the antecedents of A are identical with those attributes which cannot possibly belong to E, or if those attributes are identical which cannot belong to either term: for no syllogism is produced by means of these. 30For if the consequents are identical, e.g. B and F, we have the middle figure with both premisses affirmative: if the antecedents of A are identical with attributes which cannot belong to E, e.g. C with H, we have the first figure with its minor premiss negative. If attributes which cannot belong to either term are identical, 35e.g. C and H, both premisses are negative, either in the first or in the middle figure. 40But no syllogism is possible in this way.
It is clear too that the inquiry proceeds through the three terms and the two premisses, and that all the syllogisms proceed through the aforesaid figures. For it is proved that A belongs to all E, whenever an identical term is found among the Cs and Fs. 10This will be the middle term; A and E will be the extremes. So the first figure is formed. And A will belong to some E, whenever C and G are apprehended to be the same. This is the last figure: for G becomes the middle term. And A will belong to no E, when D and F are identical. Thus we have both the first figure and the middle figure; the first, because A belongs to no F, since the negative statement is convertible, 15and F belongs to all E: the middle figure because D belongs to no A, and to all E. And A will not belong to some E, whenever D and G are identical. This is the last figure: for A will belong to no G, and E will belong to all G. Clearly then 20all syllogisms proceed through the aforesaid figures, and we must not select consequents of all the terms, because no syllogism is produced from them. For (as we saw) it is not possible at all to establish a proposition from consequents, and it is not possible to refute by means of a consequent of both the terms in question: for the middle term must belong to the one, and not belong to the other.
25It is clear too that other methods of inquiry by selection of middle terms are useless to produce a syllogism, e.g. if the consequents of the terms in question are identical, or if the antecedents of A are identical with those attributes which cannot possibly belong to E, or if those attributes are identical which cannot belong to either term: for no syllogism is produced by means of these. 30For if the consequents are identical, e.g. B and F, we have the middle figure with both premisses affirmative: if the antecedents of A are identical with attributes which cannot belong to E, e.g. C with H, we have the first figure with its minor premiss negative. If attributes which cannot belong to either term are identical, 35e.g. C and H, both premisses are negative, either in the first or in the middle figure. 40But no syllogism is possible in this way.
45a
1 ἀλλὰ ταὐτὸν δεῖ λαβεῖν. εἶτα ἐν ὅσοις καὶ συμβαίνει γίνεσθαι
συλλογισμὸν τῷ ληφθῆναι ἐναντία ἢ μὴ ἐνδεχόμενα
τῷ αὐτῷ ὑπάρχειν, εἰς τοὺς προειρημένους ἅπαντα ἀναχθήσεται
τρόπους, οἷον εἰ τὸ Β καὶ τὸ Ζ ἐναντία ἢ μὴ
5 ἐνδέχεται τῷ αὐτῷ ὑπάρχειν· ἔσται μὲν γὰρ τούτων ληφθέντων
συλλογισμὸς ὅτι οὐδενὶ τῶν Ε τὸ Α ὑπάρχει, ἀλλ'
οὐκ ἐξ αὐτῶν ἀλλ' ἐκ τοῦ προειρημένου τρόπου· τὸ γὰρ Β
τῷ μὲν Α παντὶ τῷ δὲ Ε οὐδενὶ ὑπάρξει· ὥστ' ἀνάγκη ταὐτὸ
εἶναι τὸ Β τινὶ τῷ Θ. [πάλιν εἰ τὸ Β καὶ Η μὴ ἐγχωρεῖ
10 τῷ αὐτῷ παρεῖναι, ὅτι τινὶ τῷ Ε οὐχ ὑπάρξει τὸ Α· καὶ
γὰρ οὕτως τὸ μέσον ἔσται σχῆμα· τὸ γὰρ Β τῷ μὲν Α
παντὶ τῷ δὲ Ε οὐδενὶ ὑπάρξει· ὥστ' ἀνάγκη τὸ Β ταὐτόν
τινι εἶναι τῶν Θ. τὸ γὰρ μὴ ἐνδέχεσθαι τὸ Β καὶ τὸ Η
τῷ αὐτῷ ὑπάρχειν οὐδὲν διαφέρει ἢ τὸ Β τῶν Θ τινὶ ταὐτὸν
15 εἶναι· πάντα γὰρ εἴληπται τὰ μὴ ἐνδεχόμενα τῷ Ε
ὑπάρχειν.]
Φανερὸν οὖν ὅτι ἐξ αὐτῶν μὲν τούτων τῶν ἐπιβλέψεων
οὐδεὶς γίνεται συλλογισμός, ἀνάγκη δ' εἰ τὸ Β καὶ τὸ Ζ
ἐναντία, ταὐτόν τινι εἶναι τὸ Β τῶν Θ καὶ τὸν συλλογισμὸν
20 γίγνεσθαι διὰ τούτων. συμβαίνει δὴ τοῖς οὕτως ἐπισκοποῦσι
προσεπιβλέπειν ἄλλην ὁδὸν τῆς ἀναγκαίας διὰ τὸ
λανθάνειν τὴν ταὐτότητα τῶν Β καὶ τῶν Θ.
1It is evident too that we must find out which terms in this inquiry are identical, not which are different or contrary, first because the object of our investigation is the middle term, and the middle term must be not diverse but identical. Secondly, wherever it happens that a syllogism results from taking contraries or terms which cannot belong to the same thing, all arguments can be reduced to the aforesaid moods, e.g. if B and F are contraries or cannot 5belong to the same thing. For if these are taken, a syllogism will be formed to prove that A belongs to none of the Es, not however from the premisses taken but in the aforesaid mood. For B will belong to all A and to no E. Consequently B must be identical with one of the Hs. Again, if B and G cannot 10belong to the same thing, it follows that A will not belong to some of the Es: for then too we shall have the middle figure: for B will belong to all A and to no G. Consequently B must be identical with some of the Hs. For the fact that B and G cannot belong to the same thing differs in no way from the fact that B is identical with some of the Hs: 15for that includes everything which cannot belong to E.
It is clear then that from the inquiries taken by themselves no syllogism results; but if B and F are contraries B must be identical with one of the Hs, 20and the syllogism results through these terms. It turns out then that those who inquire in this manner are looking gratuitously for some other way than the necessary way because they have failed to observe the identity of the Bs with the Hs.
It is clear then that from the inquiries taken by themselves no syllogism results; but if B and F are contraries B must be identical with one of the Hs, 20and the syllogism results through these terms. It turns out then that those who inquire in this manner are looking gratuitously for some other way than the necessary way because they have failed to observe the identity of the Bs with the Hs.
Book 1,Chapter 29 (45a23–46a2)
Τὸν αὐτὸν δὲ τρόπον ἔχουσι καὶ οἱ εἰς τὸ ἀδύνατον
ἄγοντες συλλογισμοὶ τοῖς δεικτικοῖς· καὶ γὰρ οὗτοι γίνονται
25 διὰ τῶν ἑπομένων καὶ οἷς ἕπεται ἑκάτερον. καὶ ἡ αὐτὴ
ἐπίσκεψις ἐν ἀμφοῖν· ὃ γὰρ δείκνυται δεικτικῶς, καὶ διὰ
τοῦ ἀδυνάτου ἔστι συλλογίσασθαι διὰ τῶν αὐτῶν ὅρων, καὶ
ὃ διὰ τοῦ ἀδυνάτου, καὶ δεικτικῶς, οἷον ὅτι τὸ Α οὐδενὶ
τῷ Ε ὑπάρχει. κείσθω γὰρ τινὶ ὑπάρχειν· οὐκοῦν ἐπεὶ τὸ
30 Β παντὶ τῷ Α, τὸ δὲ Α τινὶ τῷ Ε, τὸ Β τινὶ τῶν Ε
ὑπάρξει· ἀλλ' οὐδενὶ ὑπῆρχεν. πάλιν ὅτι τινὶ ὑπάρχει· εἰ
γὰρ μηδενὶ τῷ Ε τὸ Α, τὸ δὲ Ε παντὶ τῷ Η, οὐδενὶ τῶν
Η ὑπάρξει τὸ Α· ἀλλὰ παντὶ ὑπῆρχεν. ὁμοίως δὲ καὶ ἐπὶ
τῶν ἄλλων προβλημάτων· ἀεὶ γὰρ ἔσται καὶ ἐν ἅπασιν ἡ
35 διὰ τοῦ ἀδυνάτου δεῖξις ἐκ τῶν ἑπομένων καὶ οἷς ἕπεται
ἑκάτερον. καὶ καθ' ἕκαστον πρόβλημα ἡ αὐτὴ σκέψις δεικτικῶς
τε βουλομένῳ συλλογίσασθαι καὶ εἰς ἀδύνατον ἀγαγεῖν·
ἐκ γὰρ τῶν αὐτῶν ὅρων ἀμφότεραι αἱ ἀποδείξεις, οἷον
εἰ δέδεικται μηδενὶ ὑπάρχειν τῷ Ε τὸ Α, ὅτι συμβαίνει
40 καὶ τὸ Β τινὶ τῷ Ε ὑπάρχειν, ὅπερ ἀδύνατον· ἐὰν ληφθῇ
τῷ μὲν Ε μηδενὶ τῷ δὲ Α παντὶ ὑπάρχειν τὸ Β, φανερὸν
23Syllogisms which lead to impossible conclusions are similar to ostensive syllogisms; they also are formed 25by means of the consequents and antecedents of the terms in question. In both cases the same inquiry is involved. For what is proved ostensively may also be concluded syllogistically per impossibile by means of the same terms; and what is proved per impossibile may also be proved ostensively, e.g. that A belongs to none of the Es. For suppose A to belong to some E: then since B 30belongs to all A and A to some of the Es, B will belong to some of the Es: but it was assumed that it belongs to none. Again we may prove that A belongs to some E: for if A belonged to none of the Es, and E belongs to all G, A will belong to none of the Gs: but it was assumed to belong to all. Similarly with the other propositions requiring proof. The proof per impossibile will always and in all cases 35be from the consequents and antecedents of the terms in question. Whatever the problem the same inquiry is necessary whether one wishes to use an ostensive syllogism or a reduction to impossibility. For both the demonstrations start from the same terms, e.g. suppose it has been proved that A belongs to no E, because it turns out that 40otherwise B belongs to some of the Es and this is impossible-if now it is assumed that B belongs to no E and to all A, it is clear that A will belong to no E.
45b
1 ὅτι οὐδενὶ τῷ Ε τὸ Α ὑπάρξει. πάλιν εἰ δεικτικῶς συλλελόγισται
τὸ Α τῷ Ε μηδενὶ ὑπάρχειν, ὑποθεμένοις ὑπάρχειν
τινὶ διὰ τοῦ ἀδυνάτου δειχθήσεται οὐδενὶ ὑπάρχον.
ὁμοίως δὲ κἀπὶ τῶν ἄλλων· ἐν ἅπασι γὰρ ἀνάγκη κοινόν
5 τινα λαβεῖν ὅρον ἄλλον τῶν ὑποκειμένων, πρὸς ὃν ἔσται τοῦ
ψεύδους ὁ συλλογισμός, ὥστ' ἀντιστραφείσης ταύτης τῆς
προτάσεως, τῆς δ' ἑτέρας ὁμοίως ἐχούσης, δεικτικὸς ἔσται
ὁ συλλογισμὸς διὰ τῶν αὐτῶν ὅρων. διαφέρει γὰρ ὁ δεικτικὸς
τοῦ εἰς τὸ ἀδύνατον, ὅτι ἐν μὲν τῷ δεικτικῷ κατ'
10 ἀλήθειαν ἀμφότεραι τίθενται αἱ προτάσεις, ἐν δὲ τῷ εἰς τὸ
ἀδύνατον ψευδῶς ἡ μία.
Ταῦτα μὲν οὖν ἔσται μᾶλλον φανερὰ διὰ τῶν ἑπομένων,
ὅταν περὶ τοῦ ἀδυνάτου λέγωμεν· νῦν δὲ τοσοῦτον
ἡμῖν ἔστω δῆλον, ὅτι εἰς ταὐτὰ βλεπτέον δεικτικῶς τε βουλομένῳ
15 συλλογίζεσθαι καὶ εἰς τὸ ἀδύνατον ἄγειν. ἐν δὲ
τοῖς ἄλλοις συλλογισμοῖς τοῖς ἐξ ὑποθέσεως, οἷον ὅσοι
κατὰ μετάληψιν ἢ κατὰ ποιότητα, ἐν τοῖς ὑποκειμένοις,
οὐκ ἐν τοῖς ἐξ ἀρχῆς ἀλλ' ἐν τοῖς μεταλαμβανομένοις, ἔσται
ἡ σκέψις, ὁ δὲ τρόπος ὁ αὐτὸς τῆς ἐπιβλέψεως. ἐπισκέψασθαι
20 δὲ δεῖ καὶ διελεῖν ποσαχῶς οἱ ἐξ ὑποθέσεως.
Δείκνυται μὲν οὖν ἕκαστον τῶν προβλημάτων οὕτως,
ἔστι δὲ καὶ ἄλλον τρόπον ἔνια συλλογίσασθαι τούτων, οἷον
τὰ καθόλου διὰ τῆς κατὰ μέρος ἐπιβλέψεως ἐξ ὑποθέσεως.
εἰ γὰρ τὸ Γ καὶ τὸ Η ταὐτὰ εἴη, μόνοις δὲ ληφθείη τοῖς
25 Η τὸ Ε ὑπάρχειν, παντὶ ἂν τῷ Ε τὸ Α ὑπάρχοι· καὶ
πάλιν εἰ τὸ Δ καὶ Η ταὐτά, μόνων δὲ τῶν Η τὸ Ε κατηγοροῖτο,
ὅτι οὐδενὶ τῷ Ε τὸ Α ὑπάρξει. φανερὸν οὖν ὅτι
καὶ οὕτως ἐπιβλεπτέον. τὸν αὐτὸν δὲ τρόπον καὶ ἐπὶ τῶν
ἀναγκαίων καὶ τῶν ἐνδεχομένων· ἡ γὰρ αὐτὴ σκέψις, καὶ
30 διὰ τῶν αὐτῶν ὅρων ἔσται τῇ τάξει τοῦ τ' ἐνδέχεσθαι καὶ
τοῦ ὑπάρχειν ὁ συλλογισμός. ληπτέον δ' ἐπὶ τῶν ἐνδεχομένων
καὶ τὰ μὴ ὑπάρχοντα δυνατὰ δ' ὑπάρχειν· δέδεικται
γὰρ ὅτι καὶ διὰ τούτων γίνεται ὁ τοῦ ἐνδέχεσθαι
συλλογισμός. ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων κατηγοριῶν.
35
Φανερὸν οὖν ἐκ τῶν εἰρημένων οὐ μόνον ὅτι ἐγχωρεῖ
διὰ ταύτης τῆς ὁδοῦ γίνεσθαι πάντας τοὺς συλλογισμούς,
ἀλλὰ καὶ ὅτι δι' ἄλλης ἀδύνατον. ἅπας μὲν γὰρ συλλογισμὸς
δέδεικται διά τινος τῶν προειρημένων σχημάτων γινόμενος,
40 ταῦτα δ' οὐκ ἐγχωρεῖ δι' ἄλλων συσταθῆναι πλὴν
διὰ τῶν ἑπομένων καὶ οἷς ἕπεται ἕκαστον· ἐκ τούτων γὰρ
1Again if it has been proved by an ostensive syllogism that A belongs to no E, assume that A belongs to some E and it will be proved per impossibile to belong to no E. Similarly with the rest. In all cases it is necessary to find 5some common term other than the subjects of inquiry, to which the syllogism establishing the false conclusion may relate, so that if this premiss is converted, and the other remains as it is, the syllogism will be ostensive by means of the same terms. For the ostensive syllogism differs from the reductio ad impossibile in this: in the ostensive syllogism both 10remisses are laid down in accordance with the truth, in the reductio ad impossibile one of the premisses is assumed falsely.
These points will be made clearer by the sequel, when we discuss the reduction to impossibility: at present this much must be clear, that we must look to terms of the kinds mentioned whether we wish to use an ostensive syllogism 15or a reduction to impossibility. In the other hypothetical syllogisms, I mean those which proceed by substitution, or by positing a certain quality, the inquiry will be directed to the terms of the problem to be proved-not the terms of the original problem, but the new terms introduced; and the method of the inquiry will be the same as before. But we must consider 20and determine in how many ways hypothetical syllogisms are possible.
Each of the problems then can be proved in the manner described; but it is possible to establish some of them syllogistically in another way, e.g. universal problems by the inquiry which leads up to a particular conclusion, with the addition of an hypothesis. For if the Cs and the Gs should be identical, but E should be assumed to belong to the Gs only, then 25A would belong to every E: and again if the Ds and the Gs should be identical, but E should be predicated of the Gs only, it follows that A will belong to none of the Es. Clearly then we must consider the matter in this way also. The method is the same whether the relation is necessary or possible. For the inquiry will be the same, and the syllogism will proceed 30through terms arranged in the same order whether a possible or a pure proposition is proved. We must find in the case of possible relations, as well as terms that belong, terms which can belong though they actually do not: for we have proved that the syllogism which establishes a possible relation proceeds through 35these terms as well. Similarly also with the other modes of predication.
It is clear then from what has been said not only that all syllogisms can be formed in this way, but also that they cannot be formed in any other. For every syllogism has been proved to be formed through one of the aforementioned figures, 40and these cannot be composed through other terms than the consequents and antecedents of the terms in question: for from these we obtain the premisses and find the middle term.
These points will be made clearer by the sequel, when we discuss the reduction to impossibility: at present this much must be clear, that we must look to terms of the kinds mentioned whether we wish to use an ostensive syllogism 15or a reduction to impossibility. In the other hypothetical syllogisms, I mean those which proceed by substitution, or by positing a certain quality, the inquiry will be directed to the terms of the problem to be proved-not the terms of the original problem, but the new terms introduced; and the method of the inquiry will be the same as before. But we must consider 20and determine in how many ways hypothetical syllogisms are possible.
Each of the problems then can be proved in the manner described; but it is possible to establish some of them syllogistically in another way, e.g. universal problems by the inquiry which leads up to a particular conclusion, with the addition of an hypothesis. For if the Cs and the Gs should be identical, but E should be assumed to belong to the Gs only, then 25A would belong to every E: and again if the Ds and the Gs should be identical, but E should be predicated of the Gs only, it follows that A will belong to none of the Es. Clearly then we must consider the matter in this way also. The method is the same whether the relation is necessary or possible. For the inquiry will be the same, and the syllogism will proceed 30through terms arranged in the same order whether a possible or a pure proposition is proved. We must find in the case of possible relations, as well as terms that belong, terms which can belong though they actually do not: for we have proved that the syllogism which establishes a possible relation proceeds through 35these terms as well. Similarly also with the other modes of predication.
It is clear then from what has been said not only that all syllogisms can be formed in this way, but also that they cannot be formed in any other. For every syllogism has been proved to be formed through one of the aforementioned figures, 40and these cannot be composed through other terms than the consequents and antecedents of the terms in question: for from these we obtain the premisses and find the middle term.
46a
1 αἱ προτάσεις καὶ ἡ τοῦ μέσου λῆψις, ὥστ' οὐδὲ συλλογισμὸν
ἐγχωρεῖ γίνεσθαι δι' ἄλλων.
1Consequently a syllogism cannot be formed by means of other terms.
Book 1,Chapter 30 (46a3–30)
Ἡ μὲν οὖν ὁδὸς κατὰ πάντων ἡ αὐτὴ καὶ περὶ φιλοσοφίαν
καὶ περὶ τέχνην ὁποιανοῦν καὶ μάθημα· δεῖ γὰρ
5 τὰ ὑπάρχοντα καὶ οἷς ὑπάρχει περὶ ἑκάτερον ἀθρεῖν, καὶ
τούτων ὡς πλείστων εὐπορεῖν, καὶ ταῦτα διὰ τῶν τριῶν ὅρων
σκοπεῖν, ἀνασκευάζοντα μὲν ὡδί, κατασκευάζοντα δὲ ὡδί,
κατὰ μὲν ἀλήθειαν ἐκ τῶν κατ' ἀλήθειαν διαγεγραμμένων
ὑπάρχειν, εἰς δὲ τοὺς διαλεκτικοὺς συλλογισμοὺς ἐκ τῶν κατὰ
10 δόξαν προτάσεων. αἱ δ' ἀρχαὶ τῶν συλλογισμῶν καθόλου
μὲν εἴρηνται, ὃν τρόπον τ' ἔχουσι καὶ ὃν τρόπον δεῖ θηρεύειν
αὐτάς, ὅπως μὴ βλέπωμεν εἰς ἅπαντα τὰ λεγόμενα,
μηδ' εἰς ταὐτὰ κατασκευάζοντες καὶ ἀνασκευάζοντες, μηδὲ
κατασκευάζοντές τε κατὰ παντὸς ἢ τινὸς καὶ ἀνασκευάζοντες
15 ἀπὸ πάντων ἢ τινῶν, ἀλλ' εἰς ἐλάττω καὶ ὡρισμένα,
καθ' ἕκαστον δὲ ἐκλέγειν τῶν ὄντων, οἷον περὶ ἀγαθοῦ ἢ
ἐπιστήμης. ἴδιαι δὲ καθ' ἑκάστην αἱ πλεῖσται. διὸ τὰς
μὲν ἀρχὰς τὰς περὶ ἕκαστον ἐμπειρίας ἐστὶ παραδοῦναι,
λέγω δ' οἷον τὴν ἀστρολογικὴν μὲν ἐμπειρίαν τῆς ἀστρολογικῆς
20 ἐπιστήμης (ληφθέντων γὰρ ἱκανῶς τῶν φαινομένων οὕτως
εὑρέθησαν αἱ ἀστρολογικαὶ ἀποδείξεις), ὁμοίως δὲ καὶ περὶ
ἄλλην ὁποιανοῦν ἔχει τέχνην τε καὶ ἐπιστήμην· ὥστ' ἐὰν ληφθῇ
τὰ ὑπάρχοντα περὶ ἕκαστον, ἡμέτερον ἤδη τὰς ἀποδείξεις
ἑτοίμως ἐμφανίζειν. εἰ γὰρ μηδὲν κατὰ τὴν ἱστορίαν παραλειφθείη
25 τῶν ἀληθῶς ὑπαρχόντων τοῖς πράγμασιν, ἕξομεν
περὶ ἅπαντος οὗ μὲν ἔστιν ἀπόδειξις, ταύτην εὑρεῖν καὶ ἀποδεικνύναι,
οὗ δὲ μὴ πέφυκεν ἀπόδειξις, τοῦτο ποιεῖν φανερόν.
Καθόλου μὲν οὖν, ὃν δεῖ τρόπον τὰς προτάσεις ἐκλέγειν,
εἴρηται σχεδόν· δι' ἀκριβείας δὲ διεληλύθαμεν ἐν τῇ
30 πραγματείᾳ τῇ περὶ τὴν διαλεκτικήν.
3The method is the same in all cases, in philosophy, in any art or study. 5We must look for the attributes and the subjects of both our terms, and we must supply ourselves with as many of these as possible, and consider them by means of the three terms, refuting statements in one way, confirming them in another, in the pursuit of truth starting from premisses in which the arrangement of the terms is in accordance with truth, while if we look for dialectical syllogisms we must start from probable premisses. 10The principles of syllogisms have been stated in general terms, both how they are characterized and how we must hunt for them, so as not to look to everything that is said about the terms of the problem or to the same points whether we are confirming or refuting, or again whether we are confirming of all or of some, and whether we are refuting of all or some. 15we must look to fewer points and they must be definite. We have also stated how we must select with reference to everything that is, e.g. about good or knowledge. But in each science the principles which are peculiar are the most numerous. Consequently it is the business of experience to give the principles which belong to each subject. I mean for example that astronomical experience supplies the principles 20of astronomical science: for once the phenomena were adequately apprehended, the demonstrations of astronomy were discovered. Similarly with any other art or science. Consequently, if the attributes of the thing are apprehended, our business will then be to exhibit readily the demonstrations. For if none 25of the true attributes of things had been omitted in the historical survey, we should be able to discover the proof and demonstrate everything which admitted of proof, and to make that clear, whose nature does not admit of proof.
In general then we have explained fairly well how we must select premisses: we have discussed the matter accurately in the 30treatise concerning dialectic.
In general then we have explained fairly well how we must select premisses: we have discussed the matter accurately in the 30treatise concerning dialectic.
Book 1,Chapter 31 (46a31–46b39)
Ὅτι δ' ἡ διὰ τῶν γενῶν διαίρεσις μικρόν τι μόριόν
ἐστι τῆς εἰρημένης μεθόδου, ῥᾴδιον ἰδεῖν· ἔστι γὰρ ἡ διαίρεσις
οἷον ἀσθενὴς συλλογισμός· ὃ μὲν γὰρ δεῖ δεῖξαι αἰτεῖται,
συλλογίζεται δ' ἀεί τι τῶν ἄνωθεν. πρῶτον δ' αὐτὸ
35 τοῦτο ἐλελήθει τοὺς χρωμένους αὐτῇ πάντας, καὶ πείθειν
ἐπεχείρουν ὡς ὄντος δυνατοῦ περὶ οὐσίας ἀπόδειξιν γενέσθαι
καὶ τοῦ τί ἐστιν. ὥστ' οὔτε ὅ τι ἐνδέχεται συλλογίσασθαι
διαιρουμένοις ξυνίεσαν, οὔτε ὅτι οὕτως ἐνεδέχετο ὥσπερ εἰρήκαμεν.
ἐν μὲν οὖν ταῖς ἀποδείξεσιν, ὅταν δέῃ τι συλλογίσασθαι
40 ὑπάρχειν, δεῖ τὸ μέσον, δι' οὗ γίνεται ὁ συλλογισμός,
31It is easy to see that division into classes is a small part of the method we have described: for division is, so to speak, a weak syllogism; for what it ought to prove, it begs, and it always establishes something more general than the attribute in question. First, this very point 35had escaped all those who used the method of division; and they attempted to persuade men that it was possible to make a demonstration of substance and essence. 40Consequently they did not understand what it is possible to prove syllogistically by division, nor did they understand that it was possible to prove syllogistically in the manner we have described.
46b
1 καὶ ἧττον ἀεὶ εἶναι καὶ μὴ καθόλου τοῦ πρώτου
τῶν ἄκρων· ἡ δὲ διαίρεσις τοὐναντίον βούλεται· τὸ γὰρ καθόλου
λαμβάνει μέσον. ἔστω γὰρ ζῷον ἐφ' οὗ Α, τὸ
δὲ θνητὸν ἐφ' οὗ Β, καὶ ἀθάνατον ἐφ' οὗ Γ, ὁ δ' ἄνθρωπος,
5 οὗ τὸν λόγον δεῖ λαβεῖν, ἐφ' οὗ τὸ Δ. ἅπαν δὴ ζῷον
λαμβάνει ἢ θνητὸν ἢ ἀθάνατον· τοῦτο δ' ἐστίν, ὃ ἂν ᾖ Α,
ἅπαν εἶναι ἢ Β ἢ Γ. πάλιν τὸν ἄνθρωπον ἀεὶ διαιρούμενος
τίθεται ζῷον εἶναι, ὥστε κατὰ τοῦ Δ τὸ Α λαμβάνει ὑπάρχειν.
ὁ μὲν οὖν συλλογισμός ἐστιν ὅτι τὸ Δ ἢ Β ἢ Γ ἅπαν
10 ἔσται, ὥστε τὸν ἄνθρωπον ἢ θνητὸν μὲν ἢ ἀθάνατον ἀναγκαῖον
εἶναι, ζῷον θνητὸν δὲ οὐκ ἀναγκαῖον, ἀλλ' αἰτεῖται·
τοῦτο δ' ἦν ὃ ἔδει συλλογίσασθαι. καὶ πάλιν θέμενος τὸ
μὲν Α ζῷον θνητόν, ἐφ' οὗ δὲ τὸ Β ὑπόπουν, ἐφ' οὗ δὲ
τὸ Γ ἄπουν, τὸν δ' ἄνθρωπον τὸ Δ, ὡσαύτως λαμβάνει
15 τὸ μὲν Α ἤτοι ἐν τῷ Β ἢ ἐν τῷ Γ εἶναι (ἅπαν γὰρ ζῷον
θνητὸν ἢ ὑπόπουν ἢ ἄπουν ἐστί), κατὰ δὲ τοῦ Δ τὸ Α (τὸν
γὰρ ἄνθρωπον ζῷον θνητὸν εἶναι ἔλαβεν)· ὥσθ' ὑπόπουν μὲν
ἢ ἄπουν εἶναι ζῷον ἀνάγκη τὸν ἄνθρωπον, ὑπόπουν δ' οὐκ
ἀνάγκη, ἀλλὰ λαμβάνει· τοῦτο δ' ἦν ὃ ἔδει πάλιν δεῖξαι.
20 καὶ τοῦτον δὴ τὸν τρόπον ἀεὶ διαιρουμένοις τὸ μὲν καθόλου
συμβαίνει αὐτοῖς μέσον λαμβάνειν, καθ' οὗ δ' ἔδει δεῖξαι
καὶ τὰς διαφορὰς ἄκρα. τέλος δέ, ὅτι τοῦτ' ἔστιν ἄνθρωπος
ἢ ὅ τι ποτ' ἂν ᾖ τὸ ζητούμενον, οὐδὲν λέγουσι σαφὲς ὥστ'
ἀναγκαῖον εἶναι· καὶ γὰρ τὴν ἄλλην ὁδὸν ποιοῦνται πᾶσαν,
25 οὐδὲ τὰς ἐνδεχομένας εὐπορίας ὑπολαμβάνοντες ὑπάρχειν.
Φανερὸν δ' ὅτι οὔτ' ἀνασκευάσαι ταύτῃ τῇ μεθόδῳ ἔστιν, οὔτε
περὶ συμβεβηκότος ἢ ἰδίου συλλογίσασθαι, οὔτε περὶ γένους,
οὔτ' ἐν οἷς ἀγνοεῖται τὸ πότερον ὡδὶ ἢ ὡδὶ ἔχει, οἷον
ἆρ' ἡ διάμετρος ἀσύμμετρος ἢ σύμμετρος. ἐὰν γὰρ λάβῃ ὅτι ἅπαν
30 μῆκος ἢ σύμμετρον ἢ ἀσύμμετρον, ἡ δὲ διάμετρος μῆκος,
συλλελόγισται ὅτι ἀσύμμετρος ἢ σύμμετρος ἡ διάμετρος.
εἰ δὲ λήψεται ἀσύμμετρον, ὃ ἔδει συλλογίσασθαι
λήψεται. οὐκ ἄρα ἔστι δεῖξαι· ἡ μὲν γὰρ ὁδὸς αὕτη, διὰ
ταύτης δ' οὐκ ἔστιν. τὸ ἀσύμμετρον ἢ σύμμετρον ἐφ' οὗ
35 Α, μῆκος Β, διάμετρος Γ. φανερὸν οὖν ὅτι οὔτε πρὸς πᾶσαν
σκέψιν ἁρμόζει τῆς ζητήσεως ὁ τρόπος, οὔτ' ἐν οἷς μάλιστα
δοκεῖ πρέπειν, ἐν τούτοις ἐστὶ χρήσιμος.
Ἐκ τίνων μὲν οὖν αἱ ἀποδείξεις γίνονται καὶ πῶς,
καὶ εἰς ὁποῖα βλεπτέον καθ' ἕκαστον πρόβλημα, φανερὸν
40 ἐκ τῶν εἰρημένων·
1In demonstrations, when there is a need to prove a positive statement, the middle term through which the syllogism is formed must always be inferior to and not comprehend the first of the extremes. But division has a contrary intention: for it takes the universal as middle. Let animal be the term signified by A, mortal by B, and immortal by C, and let man, 5whose definition is to be got, be signified by D. The man who divides assumes that every animal is either mortal or immortal: i.e. whatever is A is all either B or C. Again, always dividing, he lays it down that man is an animal, so he assumes A of D as belonging to it. Now the true conclusion is that every D is either B or C, 10consequently man must be either mortal or immortal, but it is not necessary that man should be a mortal animal-this is begged: and this is what ought to have been proved syllogistically. And again, taking A as mortal animal, B as footed, C as footless, and D as man, he assumes in the same way that 15A inheres either in B or in C (for every mortal animal is either footed or footless), and he assumes A of D (for he assumed man, as we saw, to be a mortal animal); consequently it is necessary that man should be either a footed or a footless animal; but it is not necessary that man should be footed: this he assumes: and it is just this again which he ought to have demonstrated. 20Always dividing then in this way it turns out that these logicians assume as middle the universal term, and as extremes that which ought to have been the subject of demonstration and the differentiae. In conclusion, they do not make it clear, and show it to be necessary, that this is man or whatever the subject of inquiry may be: for they pursue the other method altogether, 25never even suspecting the presence of the rich supply of evidence which might be used. It is clear that it is neither possible to refute a statement by this method of division, nor to draw a conclusion about an accident or property of a thing, nor about its genus, nor in cases in which it is unknown whether it is thus or thus, e.g. whether the diagonal is incommensurate. For if he assumes that 30every length is either commensurate or incommensurate, and the diagonal is a length, he has proved that the diagonal is either incommensurate or commensurate. But if he should assume that it is incommensurate, he will have assumed what he ought to have proved. He cannot then prove it: for this is his method, but proof is not possible by this method. Let A stand for 'incommensurate or commensurate', 35B for 'length', C for 'diagonal'. It is clear then that this method of investigation is not suitable for every inquiry, nor is it useful in those cases in which it is thought to be most suitable.
From what has been said it is clear from what elements demonstrations are formed and in what manner, and to what points we must look in each problem.
From what has been said it is clear from what elements demonstrations are formed and in what manner, and to what points we must look in each problem.
Book 1,Chapter 32 (46b40–47b14)
πῶς δ' ἀνάξομεν τοὺς συλλογισμοὺς εἰς
40Our next business is to state how we can reduce syllogisms to the aforementioned figures: for this part of the inquiry still remains.
47a
1 τὰ προειρημένα σχήματα, λεκτέον ἂν εἴη μετὰ ταῦτα·
λοιπὸν γὰρ ἔτι τοῦτο τῆς σκέψεως. εἰ γὰρ τήν τε γένεσιν
τῶν συλλογισμῶν θεωροῖμεν καὶ τοῦ εὑρίσκειν ἔχοιμεν δύναμιν,
ἔτι δὲ τοὺς γεγενημένους ἀναλύοιμεν εἰς τὰ προειρημένα
5 σχήματα, τέλος ἂν ἔχοι ἡ ἐξ ἀρχῆς πρόθεσις. συμβήσεται
δ' ἅμα καὶ τὰ πρότερον εἰρημένα ἐπιβεβαιοῦσθαι καὶ
φανερώτερα εἶναι ὅτι οὕτως ἔχει, διὰ τῶν νῦν λεχθησομένων·
δεῖ γὰρ πᾶν τὸ ἀληθὲς αὐτὸ ἑαυτῷ ὁμολογούμενον
εἶναι πάντῃ.
10 Πρῶτον μὲν οὖν δεῖ πειρᾶσθαι τὰς δύο προτάσεις ἐκλαμβάνειν
τοῦ συλλογισμοῦ (ῥᾷον γὰρ εἰς τὰ μείζω διελεῖν
ἢ τὰ ἐλάττω, μείζω δὲ τὰ συγκείμενα ἢ ἐξ ὧν),
εἶτα σκοπεῖν ποτέρα ἐν ὅλῳ καὶ ποτέρα ἐν μέρει, καί, εἰ
μὴ ἄμφω εἰλημμέναι εἶεν, αὐτὸν τιθέναι τὴν ἑτέραν. ἐνίοτε
15 γὰρ τὴν καθόλου προτείναντες τὴν ἐν ταύτῃ οὐ λαμβάνουσιν,
οὔτε γράφοντες οὔτ' ἐρωτῶντες· ἢ ταύτας μὲν προτείνουσι,
δι' ὧν δ' αὗται περαίνονται, παραλείπουσιν, ἄλλα
δὲ μάτην ἐρωτῶσιν. σκεπτέον οὖν εἴ τι περίεργον εἴληπται
καὶ εἴ τι τῶν ἀναγκαίων παραλέλειπται, καὶ τὸ μὲν θετέον
20 τὸ δ' ἀφαιρετέον, ἕως ἂν ἔλθῃ εἰς τὰς δύο προτάσεις·
ἄνευ γὰρ τούτων οὐκ ἔστιν ἀναγαγεῖν τοὺς οὕτως ἠρωτημένους λόγους.
ἐνίων μὲν οὖν ῥᾴδιον ἰδεῖν τὸ ἐνδεές, ἔνιοι δὲ λανθάνουσι
καὶ δοκοῦσι συλλογίζεσθαι διὰ τὸ ἀναγκαῖόν τι συμβαίνειν
ἐκ τῶν κειμένων, οἷον εἰ ληφθείη μὴ οὐσίας ἀναιρουμένης
25 μὴ ἀναιρεῖσθαι οὐσίαν, ἐξ ὧν δ' ἐστὶν ἀναιρουμένων, καὶ
τὸ ἐκ τούτων φθείρεσθαι· τούτων γὰρ τεθέντων ἀναγκαῖον
μὲν τὸ οὐσίας μέρος εἶναι οὐσίαν, οὐ μὴν συλλελόγισται διὰ
τῶν εἰλημμένων, ἀλλ' ἐλλείπουσι προτάσεις. πάλιν εἰ ἀνθρώπου
ὄντος ἀνάγκη ζῷον εἶναι καὶ ζῴου οὐσίαν, ἀνθρώπου
30 ὄντος ἀνάγκη οὐσίαν εἶναι· ἀλλ' οὔπω συλλελόγισται· οὐ γὰρ
ἔχουσιν αἱ προτάσεις ὡς εἴπομεν. Ἀπατώμεθα δ' ἐν τοῖς τοιούτοις
διὰ τὸ ἀναγκαῖόν τι συμβαίνειν ἐκ τῶν κειμένων, ὅτι
καὶ ὁ συλλογισμὸς ἀναγκαῖόν ἐστιν. ἐπὶ πλέον δὲ τὸ ἀναγκαῖον
ἢ ὁ συλλογισμός· ὁ μὲν γὰρ συλλογισμὸς πᾶς ἀναγκαῖον,
35 τὸ δ' ἀναγκαῖον οὐ πᾶν συλλογισμός. ὥστ' οὐκ εἴ τι
συμβαίνει τεθέντων τινῶν, πειρατέον ἀνάγειν εὐθύς, ἀλλὰ
πρῶτον ληπτέον τὰς δύο προτάσεις, εἶθ' οὕτω διαιρετέον εἰς
τοὺς ὅρους, μέσον δὲ θετέον τῶν ὅρων τὸν ἐν ἀμφοτέραις
ταῖς προτάσεσι λεγόμενον· ἀνάγκη γὰρ τὸ μέσον ἐν ἀμφοτέραις
40 ὑπάρχειν ἐν ἅπασι τοῖς σχήμασιν. Ἐὰν μὲν οὖν
1If we should investigate the production of the syllogisms and had the power of discovering them, and further if we could resolve the syllogisms produced into the aforementioned figures, 5our original problem would be brought to a conclusion. It will happen at the same time that what has been already said will be confirmed and its truth made clearer by what we are about to say. For everything that is true must in every respect agree with itself 10First then we must attempt to select the two premisses of the syllogism (for it is easier to divide into large parts than into small, and the composite parts are larger than the elements out of which they are made); next we must inquire which are universal and which particular, and if both premisses have not been stated, we must ourselves assume the one which is missing. For sometimes 15men put forward the universal premiss, but do not posit the premiss which is contained in it, either in writing or in discussion: or men put forward the premisses of the principal syllogism, but omit those through which they are inferred, and invite the concession of others to no purpose. We must inquire then whether anything unnecessary has been assumed, or anything necessary has been omitted, and we must posit the one 20and take away the other, until we have reached the two premisses: for unless we have these, we cannot reduce arguments put forward in the way described. In some arguments it is easy to see what is wanting, but some escape us, and appear to be syllogisms, because something necessary results from what has been laid down, e.g. if the assumptions were made that substance is not annihilated by the annihilation of what is not substance, 25and that if the elements out of which a thing is made are annihilated, then that which is made out of them is destroyed: these propositions being laid down, it is necessary that any part of substance is substance; this has not however been drawn by syllogism from the propositions assumed, but premisses are wanting. Again if it is necessary that animal should exist, if man does, and that substance should exist, if animal does, 30it is necessary that substance should exist if man does: but as yet the conclusion has not been drawn syllogistically: for the premisses are not in the shape we required. We are deceived in such cases because something necessary results from what is assumed, since the syllogism also is necessary. But that which is necessary is wider than the syllogism: for every syllogism is necessary, 35but not everything which is necessary is a syllogism. Consequently, though something results when certain propositions are assumed, we must not try to reduce it directly, but must first state the two premisses, then divide them into their terms. We must take that term as middle which is stated in both the remisses: for it is necessary that the middle should be found in both premisses 40in all the figures.
47b
1 κατηγορῇ καὶ κατηγορῆται τὸ μέσον, ἢ αὐτὸ μὲν κατηγορῇ,
ἄλλο δ' ἐκείνου ἀπαρνῆται, τὸ πρῶτον ἔσται σχῆμα·
ἐὰν δὲ καὶ κατηγορῇ καὶ ἀπαρνῆται ἀπό τινος, τὸ μέσον·
ἐὰν δ' ἄλλα ἐκείνου κατηγορῆται, ἢ τὸ μὲν ἀπαρνῆται τὸ
5 δὲ κατηγορῆται, τὸ ἔσχατον. οὕτω γὰρ εἶχεν ἐν ἑκάστῳ
σχήματι τὸ μέσον. ὁμοίως δὲ καὶ ἐὰν μὴ καθόλου ὦσιν
αἱ προτάσεις· ὁ γὰρ αὐτὸς διορισμὸς τοῦ μέσου. φανερὸν οὖν
ὡς ἐν ᾧ λόγῳ μὴ λέγεται ταὐτὸ πλεονάκις, ὅτι οὐ γίνεται
συλλογισμός· οὐ γὰρ εἴληπται μέσον. ἐπεὶ δ' ἔχομεν ποῖον
10 ἐν ἑκάστῳ σχήματι περαίνεται τῶν προβλημάτων, καὶ ἐν
τίνι τὸ καθόλου καὶ ἐν ποίῳ τὸ ἐν μέρει, φανερὸν ὡς οὐκ
εἰς ἅπαντα τὰ σχήματα βλεπτέον, ἀλλ' ἑκάστου προβλήματος
εἰς τὸ οἰκεῖον. ὅσα δ' ἐν πλείοσι περαίνεται, τῇ τοῦ
μέσου θέσει γνωριοῦμεν τὸ σχῆμα.
1If then the middle term is a predicate and a subject of predication, or if it is a predicate, and something else is denied of it, we shall have the first figure: if it both is a predicate and is denied of something, the middle figure: if other things are predicated of it, or one is denied, 5the other predicated, the last figure. For it was thus that we found the middle term placed in each figure. It is placed similarly too if the premisses are not universal: for the middle term is determined in the same way. Clearly then, if the same term is not stated more than once in the course of an argument, a syllogism cannot be made: for a middle term has not been taken. Since we know what sort of thesis 10is established in each figure, and in which the universal, in what sort the particular is described, clearly we must not look for all the figures, but for that which is appropriate to the thesis in hand. If the thesis is established in more figures than one, we shall recognize the figure by the position of the middle term.
Book 1,Chapter 33 (47b15–39)
15 Πολλάκις μὲν οὖν ἀπατᾶσθαι συμβαίνει περὶ τοὺς συλλογισμοὺς
διὰ τὸ ἀναγκαῖον, ὥσπερ εἴρηται πρότερον, ἐνίοτε
δὲ παρὰ τὴν ὁμοιότητα τῆς τῶν ὅρων θέσεως· ὅπερ οὐ χρὴ
λανθάνειν ἡμᾶς. οἷον εἰ τὸ Α κατὰ τοῦ Β λέγεται καὶ τὸ Β
κατὰ τοῦ Γ· δόξειε γὰρ ἂν οὕτως ἐχόντων τῶν ὅρων εἶναι
20 συλλογισμός, οὐ γίνεται δ' οὔτ' ἀναγκαῖον οὐδὲν οὔτε συλλογισμός.
ἔστω γὰρ ἐφ' ᾧ Α τὸ ἀεὶ εἶναι, ἐφ' ᾧ δὲ Β διανοητὸς
Ἀριστομένης, τὸ δ' ἐφ' ᾧ Γ Ἀριστομένης. ἀληθὲς δὴ τὸ
Α τῷ Β ὑπάρχειν· ἀεὶ γάρ ἐστι διανοητὸς Ἀριστομένης.
ἀλλὰ καὶ τὸ Β τῷ Γ· ὁ γὰρ Ἀριστομένης ἐστὶ διανοητὸς
25 Ἀριστομένης. τὸ δ' Α τῷ Γ οὐχ ὑπάρχει· φθαρτὸς γάρ
ἐστιν ὁ Ἀριστομένης. οὐ γὰρ ἐγίνετο συλλογισμὸς οὕτως
ἐχόντων τῶν ὅρων, ἀλλ' ἔδει καθόλου τὴν Α Β ληφθῆναι
πρότασιν. τοῦτο δὲ ψεῦδος, τὸ ἀξιοῦν πάντα τὸν διανοητὸν
Ἀριστομένην ἀεὶ εἶναι, φθαρτοῦ ὄντος Ἀριστομένους. πάλιν
30 ἔστω τὸ μὲν ἐφ' ᾧ Γ Μίκκαλος, τὸ δ' ἐφ' ᾧ Β μουσικὸς
Μίκκαλος, ἐφ' ᾧ δὲ τὸ Α τὸ φθείρεσθαι αὔριον. ἀληθὲς
δὴ τὸ Β τοῦ Γ κατηγορεῖν· ὁ γὰρ Μίκκαλός ἐστι μουσικὸς
Μίκκαλος. ἀλλὰ καὶ τὸ Α τοῦ Β· φθείροιτο γὰρ ἂν αὔριον
μουσικὸς Μίκκαλος. τὸ δέ γε Α τοῦ Γ ψεῦδος. τοῦτο
35 δὴ ταὐτόν ἐστι τῷ πρότερον· οὐ γὰρ ἀληθὲς καθόλου, Μίκκαλος
μουσικὸς ὅτι φθείρεται αὔριον· τούτου δὲ μὴ ληφθέντος
οὐκ ἦν συλλογισμός.
Αὕτη μὲν οὖν ἡ ἀπάτη γίνεται ἐν τῷ παρὰ μικρόν·
ὡς γὰρ οὐδὲν διαφέρον εἰπεῖν τόδε τῷδε ὑπάρχειν ἢ τόδε
40 τῷδε παντὶ ὑπάρχειν, συγχωροῦμεν.
15Men are frequently deceived about syllogisms because the inference is necessary, as has been said above; sometimes they are deceived by the similarity in the positing of the terms; and this ought not to escape our notice. E.g. if A is stated of B, and B of C: it would seem that a syllogism is possible since the terms stand thus: 20but nothing necessary results, nor does a syllogism. Let A represent the term 'being eternal', B 'Aristomenes as an object of thought', C 'Aristomenes'. It is true then that A belongs to B. For Aristomenes as an object of thought is eternal. But B also belongs to C: for Aristomenes is Aristomenes as an object of thought. 25But A does not belong to C: for Aristomenes is perishable. For no syllogism was made although the terms stood thus: that required that the premiss Ab should be stated universally. But this is false, that every Aristomenes who is an object of thought is eternal, since Aristomenes is perishable. Again 30let C stand for 'Miccalus', B for 'musical Miccalus', A for 'perishing to-morrow'. It is true to predicate B of C: for Miccalus is musical Miccalus. Also A can be predicated of B: for musical Miccalus might perish to-morrow. But to state A of C is false at any rate. This argument 35then is identical with the former; for it is not true universally that musical Miccalus perishes to-morrow: but unless this is assumed, no syllogism (as we have shown) is possible.
This deception then arises through ignoring a small distinction. For if we accept the conclusion as though it made no difference whether we said 'This belong to that' or 'This belongs to all of that'.
This deception then arises through ignoring a small distinction. For if we accept the conclusion as though it made no difference whether we said 'This belong to that' or 'This belongs to all of that'.
Book 1,Chapter 34 (47b40–48a28)
πολλάκις δὲ διαψεύδεσθαι
40Men will frequently fall into fallacies through not setting out the terms of the premiss well, e.g.
48a
1 συμπεσεῖται παρὰ τὸ μὴ καλῶς ἐκτίθεσθαι τοὺς
κατὰ τὴν πρότασιν ὅρους, οἷον εἰ τὸ μὲν Α εἴη ὑγίεια, τὸ
δ' ἐφ' ᾧ Β νόσος, ἐφ' ᾧ δὲ Γ ἄνθρωπος. ἀληθὲς γὰρ εἰπεῖν
ὅτι τὸ Α οὐδενὶ τῷ Β ἐνδέχεται ὑπάρχειν (οὐδεμιᾷ
5 γὰρ νόσῳ ὑγίεια ὑπάρχει), καὶ πάλιν ὅτι τὸ Β παντὶ τῷ
Γ ὑπάρχει (πᾶς γὰρ ἄνθρωπος δεκτικὸς νόσου). δόξειεν ἂν
οὖν συμβαίνειν μηδενὶ ἀνθρώπῳ ἐνδέχεσθαι ὑγίειαν ὑπάρχειν.
τούτου δ' αἴτιον τὸ μὴ καλῶς ἐκκεῖσθαι τοὺς ὅρους
κατὰ τὴν λέξιν, ἐπεὶ μεταληφθέντων τῶν κατὰ τὰς ἕξεις
10 οὐκ ἔσται συλλογισμός, οἷον ἀντὶ μὲν τῆς ὑγιείας εἰ τεθείη
τὸ ὑγιαῖνον, ἀντὶ δὲ τῆς νόσου τὸ νοσοῦν. οὐ γὰρ ἀληθὲς
εἰπεῖν ὡς οὐκ ἐνδέχεται τῷ νοσοῦντι τὸ ὑγιαίνειν ὑπάρξαι.
τούτου δὲ μὴ ληφθέντος οὐ γίνεται συλλογισμός, εἰ μὴ τοῦ
ἐνδέχεσθαι· τοῦτο δ' οὐκ ἀδύνατον· ἐνδέχεται γὰρ μηδενὶ
15 ἀνθρώπῳ ὑπάρχειν ὑγίειαν. πάλιν ἐπὶ τοῦ μέσου σχήματος
ὁμοίως ἔσται τὸ ψεῦδος· τὴν γὰρ ὑγίειαν νόσῳ μὲν οὐδεμιᾷ
ἀνθρώπῳ δὲ παντὶ ἐνδέχεται ὑπάρχειν, ὥστ' οὐδενὶ ἀνθρώπῳ
νόσον. ἐν δὲ τῷ τρίτῳ σχήματι κατὰ τὸ ἐνδέχεσθαι συμβαίνει
τὸ ψεῦδος, καὶ γὰρ ὑγίειαν καὶ νόσον καὶ ἐπιστήμην
20 καὶ ἄγνοιαν καὶ ὅλως τὰ ἐναντία τῷ αὐτῷ ἐνδέχεται
ὑπάρχειν, ἀλλήλοις δ' ἀδύνατον. τοῦτο δ' ἀνομολογούμενον
τοῖς προειρημένοις· ὅτε γὰρ τῷ αὐτῷ πλείω ἐνεδέχετο ὑπάρχειν,
ἐνεδέχετο καὶ ἀλλήλοις.
Φανερὸν οὖν ὅτι ἐν ἅπασι τούτοις ἡ ἀπάτη γίνεται παρὰ
25 τὴν τῶν ὅρων ἔκθεσιν· μεταληφθέντων γὰρ τῶν κατὰ τὰς
ἕξεις οὐδὲν γίνεται ψεῦδος. δῆλον οὖν ὅτι κατὰ τὰς τοιαύτας
προτάσεις ἀεὶ τὸ κατὰ τὴν ἕξιν ἀντὶ τῆς ἕξεως μεταληπτέον
καὶ θετέον ὅρον.
1suppose A to be health, B disease, C man. It is true to say that A cannot belong to any B (for health belongs to no disease) 5and again that B belongs to every C (for every man is capable of disease). It would seem to follow that health cannot belong to any man. The reason for this is that the terms are not set out well in the statement, since if the things which are in the conditions are substituted, 10no syllogism can be made, e.g. if 'healthy' is substituted for 'health' and 'diseased' for 'disease'. For it is not true to say that being healthy cannot belong to one who is diseased. But unless this is assumed no conclusion results, save in respect of possibility: but such a conclusion is not impossible: for it is possible that 15health should belong to no man. Again the fallacy may occur in a similar way in the middle figure: 'it is not possible that health should belong to any disease, but it is possible that health should belong to every man, consequently it is not possible that disease should belong to any man'. In the third figure the fallacy results in reference to possibility. For health and diseae and knowledge 20and ignorance, and in general contraries, may possibly belong to the same thing, but cannot belong to one another. This is not in agreement with what was said before: for we stated that when several things could belong to the same thing, they could belong to one another.
It is evident then that in all these cases the fallacy arises from 25the setting out of the terms: for if the things that are in the conditions are substituted, no fallacy arises. It is clear then that in such premisses what possesses the condition ought always to be substituted for the condition and taken as the term.
It is evident then that in all these cases the fallacy arises from 25the setting out of the terms: for if the things that are in the conditions are substituted, no fallacy arises. It is clear then that in such premisses what possesses the condition ought always to be substituted for the condition and taken as the term.
Book 1,Chapter 35 (48a29–39)
Οὐ δεῖ δὲ τοὺς ὅρους ἀεὶ ζητεῖν ὀνόματι ἐκτίθεσθαι·
30 πολλάκις γὰρ ἔσονται λόγοι οἷς οὐ κεῖται ὄνομα· διὸ χαλεπὸν
ἀνάγειν τοὺς τοιούτους συλλογισμούς. ἐνίοτε δὲ καὶ ἀπατᾶσθαι
συμβήσεται διὰ τὴν τοιαύτην ζήτησιν, οἷον ὅτι τῶν
ἀμέσων ἔστι συλλογισμός. ἔστω τὸ Α δύο ὀρθαί, τὸ ἐφ' ᾧ
Β τρίγωνον, ἐφ' ᾧ δὲ Γ ἰσοσκελές. τῷ μὲν οὖν Γ ὑπάρχει
35 τὸ Α διὰ τὸ Β, τῷ δὲ Β οὐκέτι δι' ἄλλο (καθ' αὑτὸ γὰρ
τὸ τρίγωνον ἔχει δύο ὀρθάς), ὥστ' οὐκ ἔσται μέσον τοῦ Α Β,
ἀποδεικτοῦ ὄντος. φανερὸν γὰρ ὅτι τὸ μέσον οὐχ οὕτως ἀεὶ
ληπτέον ὡς τόδε τι, ἀλλ' ἐνίοτε λόγον, ὅπερ συμβαίνει κἀπὶ
τοῦ λεχθέντος.
29We must not always seek to set out the terms a single word: 30for we shall often have complexes of words to which a single name is not given. Hence it is difficult to reduce syllogisms with such terms. Sometimes too fallacies will result from such a search, e.g. the belief that syllogism can establish that which has no mean. Let A stand for two right angles, B for triangle, C for isosceles triangle. A then belongs to C because of B: 35but A belongs to B without the mediation of another term: for the triangle in virtue of its own nature contains two right angles, consequently there will be no middle term for the proposition AB, although it is demonstrable. For it is clear that the middle must not always be assumed to be an individual thing, but sometimes a complex of words, as happens in the case mentioned.
Book 1,Chapter 36 (48a40–49a5)
40 Τὸ δὲ ὑπάρχειν τὸ πρῶτον τῷ μέσῳ καὶ τοῦτο τῷ
ἄκρῳ οὐ δεῖ λαμβάνειν ὡς αἰεὶ κατηγορηθησομένων ἀλλήλων
40That the first term belongs to the middle, and the middle to the extreme, must not be understood in the sense that they can always be predicated of one another or that the first term will be predicated of the middle in the same way as the middle is predicated of the last term.
48b
1 ἢ ὁμοίως τό τε πρῶτον τοῦ μέσου καὶ τοῦτο τοῦ ἐσχάτου.
καὶ ἐπὶ τοῦ μὴ ὑπάρχειν δ' ὡσαύτως. ἀλλ' ὁσαχῶς
τὸ εἶναι λέγεται καὶ τὸ ἀληθὲς εἰπεῖν αὐτὸ τοῦτο, τοσαυταχῶς
οἴεσθαι χρὴ σημαίνειν καὶ τὸ ὑπάρχειν. οἷον ὅτι
5 τῶν ἐναντίων ἔστι μία ἐπιστήμη. ἔστω γὰρ τὸ Α τὸ μίαν
εἶναι ἐπιστήμην, τὰ ἐναντία ἀλλήλοις ἐφ' οὗ Β. τὸ δὴ Α
τῷ Β ὑπάρχει οὐχ ὥστε τὰ ἐναντία [τὸ] μίαν εἶναι [αὐτῶν]
ἐπιστήμην, ἀλλ' ὅτι ἀληθὲς εἰπεῖν κατ' αὐτῶν μίαν εἶναι
αὐτῶν ἐπιστήμην.
10 Συμβαίνει δ' ὁτὲ μὲν ἐπὶ τοῦ μέσου τὸ πρῶτον λέγεσθαι,
τὸ δὲ μέσον ἐπὶ τοῦ τρίτου μὴ λέγεσθαι, οἷον εἰ
ἡ σοφία ἐστὶν ἐπιστήμη, τοῦ δ' ἀγαθοῦ ἐστὶν ἡ σοφία, συμπέρασμα
ὅτι τοῦ ἀγαθοῦ ἔστιν ἐπιστήμη· τὸ μὲν δὴ ἀγαθὸν
οὐκ ἔστιν ἐπιστήμη, ἡ δὲ σοφία ἐστὶν ἐπιστήμη. ὁτὲ δὲ τὸ
15 μὲν μέσον ἐπὶ τοῦ τρίτου λέγεται, τὸ δὲ πρῶτον ἐπὶ τοῦ μέσου
οὐ λέγεται, οἷον εἰ τοῦ ποιοῦ παντὸς ἔστιν ἐπιστήμη ἢ
ἐναντίου, τὸ δ' ἀγαθὸν καὶ ἐναντίον καὶ ποιόν, συμπέρασμα
μὲν ὅτι τοῦ ἀγαθοῦ ἔστιν ἐπιστήμη, οὐκ ἔστι δὲ τὸ ἀγαθὸν ἐπιστήμη
οὐδὲ τὸ ποιὸν οὐδὲ τὸ ἐναντίον, ἀλλὰ τὸ ἀγαθὸν ταῦτα.
20 ἔστι δὲ μήτε τὸ πρῶτον κατὰ τοῦ μέσου μήτε τοῦτο κατὰ τοῦ
τρίτου, τοῦ πρώτου κατὰ τοῦ τρίτου ὁτὲ μὲν λεγομένου ὁτὲ δὲ μὴ
λεγομένου. οἷον εἰ οὗ ἐπιστήμη ἔστιν, ἔστι τούτου γένος, τοῦ δ'
ἀγαθοῦ ἔστιν ἐπιστήμη, συμπέρασμα ὅτι τοῦ ἀγαθοῦ ἔστι γένος·
κατηγορεῖται δ' οὐδὲν κατ' οὐδενός. εἰ δ' οὗ ἔστιν ἐπιστήμη,
25 γένος ἐστὶ τοῦτο, τοῦ δ' ἀγαθοῦ ἔστιν ἐπιστήμη, συμπέρασμα
ὅτι τἀγαθόν ἐστι γένος· κατὰ μὲν δὴ τοῦ ἄκρου κατηγορεῖται
τὸ πρῶτον, κατ' ἀλλήλων δ' οὐ λέγεται. Τὸν αὐτὸν δὴ
τρόπον καὶ ἐπὶ τοῦ μὴ ὑπάρχειν ληπτέον. οὐ γὰρ ἀεὶ σημαίνει
τὸ μὴ ὑπάρχειν τόδε τῷδε μὴ εἶναι τόδε τόδε, ἀλλ'
30 ἐνίοτε τὸ μὴ εἶναι τόδε τοῦδε ἢ τόδε τῷδε, οἷον ὅτι οὐκ ἔστι
κινήσεως κίνησις ἢ γενέσεως γένεσις, ἡδονῆς δ' ἔστιν· οὐκ ἄρα
ἡ ἡδονὴ γένεσις. ἢ πάλιν ὅτι γέλωτος μὲν ἔστι σημεῖον, σημείου
δ' οὐκ ἔστι σημεῖον, ὥστ' οὐ σημεῖον ὁ γέλως. ὁμοίως
δὲ κἀν τοῖς ἄλλοις ἐν ὅσοις ἀναιρεῖται τὸ πρόβλημα τῷ
35 λέγεσθαί πως πρὸς αὐτὸ τὸ γένος. πάλιν ὅτι ὁ καιρὸς οὐκ
ἔστι χρόνος δέων· θεῷ γὰρ καιρὸς μὲν ἔστι, χρόνος δ' οὐκ
ἔστι δέων διὰ τὸ μηδὲν εἶναι θεῷ ὠφέλιμον. ὅρους μὲν γὰρ
θετέον καιρὸν καὶ χρόνον δέοντα καὶ θεόν, τὴν δὲ πρότασιν
ληπτέον κατὰ τὴν τοῦ ὀνόματος πτῶσιν. ἁπλῶς γὰρ τοῦτο
40 λέγομεν κατὰ πάντων, ὅτι τοὺς μὲν ὅρους ἀεὶ θετέον κατὰ
τὰς κλήσεις τῶν ὀνομάτων, οἷον ἄνθρωπος ἢ ἀγαθόν ἢ ἐναντία,
1The same holds if the premisses are negative. But we must suppose the verb 'to belong' to have as many meanings as the senses in which the verb 'to be' is used, and in which the assertion that a thing 'is' may be said to be true. Take for example the statement that 5there is a single science of contraries. Let A stand for 'there being a single science', and B for things which are contrary to one another. Then A belongs to B, not in the sense that contraries are the fact of there being a single science of them, but in the sense that it is true to say of the contraries that there is a single science of them.
10It happens sometimes that the first term is stated of the middle, but the middle is not stated of the third term, e.g. if wisdom is knowledge, and wisdom is of the good, the conclusion is that there is knowledge of the good. The good then is not knowledge, though wisdom is knowledge. 15Sometimes the middle term is stated of the third, but the first is not stated of the middle, e.g. if there is a science of everything that has a quality, or is a contrary, and the good both is a contrary and has a quality, the conclusion is that there is a science of the good, but the good is not science, nor is that which has a quality or is a contrary, though the good is both of these. 20Sometimes neither the first term is stated of the middle, nor the middle of the third, while the first is sometimes stated of the third, and sometimes not: e.g. if there is a genus of that of which there is a science, and if there is a science of the good, we conclude that there is a genus of the good. But nothing is predicated of anything. And if that of which there is a science 25is a genus, and if there is a science of the good, we conclude that the good is a genus. The first term then is predicated of the extreme, but in the premisses one thing is not stated of another.
The same holds good where the relation is negative. For 'that does not belong to this' does not always mean that 'this is not that', 30but sometimes that 'this is not of that' or 'for that', e.g. 'there is not a motion of a motion or a becoming of a becoming, but there is a becoming of pleasure: so pleasure is not a becoming.' Or again it may be said that there is a sign of laughter, but there is not a sign of a sign, consequently laughter is not a sign. This holds in the other cases too, in which the thesis is refuted because the genus is asserted in a particular way, in relation to the terms of the thesis. 35Again take the inference 'opportunity is not the right time: for opportunity belongs to God, but the right time does not, since nothing is useful to God'. We must take as terms opportunity-right time-God: but the premiss must be understood according to the case of the noun. For we state this universally without qualification, 40that the terms ought always to be stated in the nominative, e.g. man, good, contraries, not in oblique cases, e.g.
10It happens sometimes that the first term is stated of the middle, but the middle is not stated of the third term, e.g. if wisdom is knowledge, and wisdom is of the good, the conclusion is that there is knowledge of the good. The good then is not knowledge, though wisdom is knowledge. 15Sometimes the middle term is stated of the third, but the first is not stated of the middle, e.g. if there is a science of everything that has a quality, or is a contrary, and the good both is a contrary and has a quality, the conclusion is that there is a science of the good, but the good is not science, nor is that which has a quality or is a contrary, though the good is both of these. 20Sometimes neither the first term is stated of the middle, nor the middle of the third, while the first is sometimes stated of the third, and sometimes not: e.g. if there is a genus of that of which there is a science, and if there is a science of the good, we conclude that there is a genus of the good. But nothing is predicated of anything. And if that of which there is a science 25is a genus, and if there is a science of the good, we conclude that the good is a genus. The first term then is predicated of the extreme, but in the premisses one thing is not stated of another.
The same holds good where the relation is negative. For 'that does not belong to this' does not always mean that 'this is not that', 30but sometimes that 'this is not of that' or 'for that', e.g. 'there is not a motion of a motion or a becoming of a becoming, but there is a becoming of pleasure: so pleasure is not a becoming.' Or again it may be said that there is a sign of laughter, but there is not a sign of a sign, consequently laughter is not a sign. This holds in the other cases too, in which the thesis is refuted because the genus is asserted in a particular way, in relation to the terms of the thesis. 35Again take the inference 'opportunity is not the right time: for opportunity belongs to God, but the right time does not, since nothing is useful to God'. We must take as terms opportunity-right time-God: but the premiss must be understood according to the case of the noun. For we state this universally without qualification, 40that the terms ought always to be stated in the nominative, e.g. man, good, contraries, not in oblique cases, e.g.
49a
1 οὐκ ἀνθρώπου ἢ ἀγαθοῦ ἢ ἐναντίων, τὰς δὲ προτάσεις
ληπτέον κατὰ τὰς ἑκάστου πτώσεις· ἢ γὰρ ὅτι τούτῳ, οἷον
τὸ ἴσον, ἢ ὅτι τούτου, οἷον τὸ διπλάσιον, ἢ ὅτι τοῦτο, οἷον
τὸ τύπτον ἢ ὁρῶν, ἢ ὅτι οὗτος, οἷον ὁ ἄνθρωπος ζῷον, ἢ
5 εἴ πως ἄλλως πίπτει τοὔνομα κατὰ τὴν πρότασιν.
1of man, of a good, of contraries, but the premisses ought to be understood with reference to the cases of each term-either the dative, e.g. 'equal to this', or the genitive, e.g. 'double of this', or the accusative, e.g. 'that which strikes or sees this', or the nominative, e.g. 'man is an animal', 5or in whatever other way the word falls in the premiss.
Book 1,Chapter 37 (49a6–10)
Τὸ δ' ὑπάρχειν τόδε τῷδε καὶ τὸ ἀληθεύεσθαι τόδε
κατὰ τοῦδε τοσαυταχῶς ληπτέον ὁσαχῶς αἱ κατηγορίαι
διῄρηνται, καὶ ταύτας ἢ πῇ ἢ ἁπλῶς, ἔτι ἢ ἁπλᾶς ἢ συμπεπλεγμένας·
ὁμοίως δὲ καὶ τὸ μὴ ὑπάρχειν. ἐπισκεπτέον
10 δὲ ταῦτα καὶ διοριστέον βέλτιον.
6The expressions 'this belongs to that' and 'this holds true of that' must be understood in as many ways as there are different categories, and these categories must be taken either with or without qualification, and further as simple or compound: the same holds good of the corresponding negative expressions. We must consider 10these points and define them better.
Book 1,Chapter 38 (49a11–49b2)
Τὸ δ' ἐπαναδιπλούμενον ἐν ταῖς προτάσεσι πρὸς τῷ
πρώτῳ ἄκρῳ θετέον, οὐ πρὸς τῷ μέσῳ. λέγω δ' οἷον εἰ γένοιτο
συλλογισμὸς ὅτι τῆς δικαιοσύνης ἔστιν ἐπιστήμη ὅτι
ἀγαθόν, τὸ ὅτι ἀγαθόν ἢ ᾗ ἀγαθόν πρὸς τῷ πρώτῳ θετέον.
15 ἔστω γὰρ τὸ Α ἐπιστήμη ὅτι ἀγαθόν, ἐφ' ᾧ δὲ Β ἀγαθόν,
ἐφ' ᾧ δὲ Γ δικαιοσύνη. τὸ δὴ Α ἀληθὲς τοῦ Β κατηγορῆσαι·
τοῦ γὰρ ἀγαθοῦ ἔστιν ἐπιστήμη ὅτι ἀγαθόν. ἀλλὰ καὶ
τὸ Β τοῦ Γ· ἡ γὰρ δικαιοσύνη ὅπερ ἀγαθόν. οὕτω μὲν οὖν γίνεται
ἀνάλυσις. εἰ δὲ πρὸς τῷ Β τεθείη τὸ ὅτι ἀγαθόν, οὐκ
20 ἔσται· τὸ μὲν γὰρ Α κατὰ τοῦ Β ἀληθὲς ἔσται, τὸ δὲ Β
κατὰ τοῦ Γ οὐκ ἀληθὲς ἔσται· τὸ γὰρ ἀγαθὸν ὅτι ἀγαθὸν
κατηγορεῖν τῆς δικαιοσύνης ψεῦδος καὶ οὐ συνετόν. ὁμοίως δὲ
καὶ εἰ τὸ ὑγιεινὸν δειχθείη ὅτι ἔστιν ἐπιστητὸν ᾗ ἀγαθόν, ἢ
τραγέλαφος ᾗ μὴ ὄν, ἢ ὁ ἄνθρωπος φθαρτὸν ᾗ
25 αἰσθητόν· ἐν ἅπασι γὰρ τοῖς ἐπικατηγορουμένοις πρὸς τῷ
ἄκρῳ τὴν ἐπαναδίπλωσιν θετέον.
Οὐχ ἡ αὐτὴ δὲ θέσις τῶν ὅρων ὅταν ἁπλῶς τι συλλογισθῇ
καὶ ὅταν τόδε τι ἢ πῇ ἢ πώς, λέγω δ' οἷον ὅταν
τἀγαθὸν ἐπιστητὸν δειχθῇ καὶ ὅταν ἐπιστητὸν ὅτι ἀγαθόν·
30 ἀλλ' εἰ μὲν ἁπλῶς ἐπιστητὸν δέδεικται, μέσον θετέον τὸ
ὄν, εἰ δ' ὅτι ἀγαθόν, τὸ τὶ ὄν. ἔστω γὰρ τὸ μὲν Α ἐπιστήμη
ὅτι τὶ ὄν, ἐφ' ᾧ δὲ Β ὄν τι, τὸ δ' ἐφ' ᾧ Γ ἀγαθόν. ἀληθὲς
δὴ τὸ Α τοῦ Β κατηγορεῖν· ἦν γὰρ ἐπιστήμη τοῦ τινὸς ὄντος
ὅτι τὶ ὄν. ἀλλὰ καὶ τὸ Β τοῦ Γ· τὸ γὰρ ἐφ' ᾧ Γ ὄν
35 τι. ὥστε καὶ τὸ Α τοῦ Γ· ἔσται ἄρα ἐπιστήμη τἀγαθοῦ ὅτι
ἀγαθόν· ἦν γὰρ τὸ τὶ ὂν τῆς ἰδίου σημεῖον οὐσίας. εἰ δὲ τὸ
ὂν μέσον ἐτέθη καὶ πρὸς τῷ ἄκρῳ τὸ ὂν ἁπλῶς καὶ μὴ τὸ
τὶ ὂν ἐλέχθη, οὐκ ἂν ἦν συλλογισμὸς ὅτι ἔστιν ἐπιστήμη τἀγαθοῦ
ὅτι ἀγαθόν, ἀλλ' ὅτι ὄν, οἷον ἐφ' ᾧ τὸ Α ἐπιστήμη
11A term which is repeated in the premisses ought to be joined to the first extreme, not to the middle. I mean for example that if a syllogism should be made proving that there is knowledge of justice, that it is good, the expression 'that it is good' (or 'qua good') should be joined to the first term. 15Let A stand for 'knowledge that it is good', B for good, C for justice. It is true to predicate A of B. For of the good there is knowledge that it is good. Also it is true to predicate B of C. For justice is identical with a good. In this way an analysis of the argument can be made. But if the expression 'that it is good' were added to B, the conclusion will not follow: 20for A will be true of B, but B will not be true of C. For to predicate of justice the term 'good that it is good' is false and not intelligible. Similarly if it should be proved that the healthy is an object of knowledge qua good, of goat-stag an object of knowledge qua not existing, or man perishable qua an object of sense: 25in every case in which an addition is made to the predicate, the addition must be joined to the extreme.
The position of the terms is not the same when something is established without qualification and when it is qualified by some attribute or condition, e.g. when the good is proved to be an object of knowledge and when it is proved to be an object of knowledge that it is good. 30If it has been proved to be an object of knowledge without qualification, we must put as middle term 'that which is', but if we add the qualification 'that it is good', the middle term must be 'that which is something'. Let A stand for 'knowledge that it is something', B stand for 'something', and C stand for 'good'. It is true to predicate A of B: for ex hypothesi there is a science of that which is something, that it is something. B too is true of C: for that which C represents is something. 35Consequently A is true of C: there will then be knowledge of the good, that it is good: for ex hypothesi the term 'something' indicates the thing's special nature. But if 'being' were taken as middle and 'being' simply were joined to the extreme, not 'being something', we should not have had a syllogism proving that there is knowledge of the good, that it is good, but that it is; e.g.
The position of the terms is not the same when something is established without qualification and when it is qualified by some attribute or condition, e.g. when the good is proved to be an object of knowledge and when it is proved to be an object of knowledge that it is good. 30If it has been proved to be an object of knowledge without qualification, we must put as middle term 'that which is', but if we add the qualification 'that it is good', the middle term must be 'that which is something'. Let A stand for 'knowledge that it is something', B stand for 'something', and C stand for 'good'. It is true to predicate A of B: for ex hypothesi there is a science of that which is something, that it is something. B too is true of C: for that which C represents is something. 35Consequently A is true of C: there will then be knowledge of the good, that it is good: for ex hypothesi the term 'something' indicates the thing's special nature. But if 'being' were taken as middle and 'being' simply were joined to the extreme, not 'being something', we should not have had a syllogism proving that there is knowledge of the good, that it is good, but that it is; e.g.
49b
1 ὅτι ὄν, ἐφ' ᾧ Β ὄν, ἐφ' ᾧ Γ ἀγαθόν. φανερὸν οὖν ὅτι ἐν
τοῖς ἐν μέρει συλλογισμοῖς οὕτως ληπτέον τοὺς ὅρους.
1let A stand for knowledge that it is, B for being, C for good. Clearly then in syllogisms which are thus limited we must take the terms in the way stated.
Book 1,Chapter 39 (49b3–9)
Δεῖ δὲ καὶ μεταλαμβάνειν ἃ τὸ αὐτὸ δύναται, ὀνόματα
ἀντ' ὀνομάτων καὶ λόγους ἀντὶ λόγων καὶ ὄνομα καὶ
5 λόγον, καὶ ἀεὶ ἀντὶ τοῦ λόγου τοὔνομα λαμβάνειν· ῥᾴων γὰρ
ἡ τῶν ὅρων ἔκθεσις. οἷον εἰ μηδὲν διαφέρει εἰπεῖν τὸ ὑποληπτὸν
τοῦ δοξαστοῦ μὴ εἶναι γένος ἢ μὴ εἶναι ὅπερ ὑποληπτόν
τι τὸ δοξαστόν (ταὐτὸν γὰρ τὸ σημαινόμενον), ἀντὶ τοῦ λόγου
τοῦ λεχθέντος τὸ ὑποληπτὸν καὶ τὸ δοξαστὸν ὅρους θετέον.
3We ought also to exchange terms which have the same value, word for word, and phrase for phrase, and word and phrase, 5and always take a word in preference to a phrase: for thus the setting out of the terms will be easier. For example if it makes no difference whether we say that the supposable is not the genus of the opinable or that the opinable is not identical with a particular kind of supposable (for what is meant is the same in both statements), it is better to take as the terms the supposable and the opinable in preference to the phrase suggested.
Book 1,Chapter 40 (49b10–13)
10 Ἐπεὶ δ' οὐ ταὐτόν ἐστι τὸ εἶναι τὴν ἡδονὴν ἀγαθὸν καὶ
τὸ εἶναι τὴν ἡδονὴν τὸ ἀγαθόν, οὐχ ὁμοίως θετέον τοὺς ὅρους,
ἀλλ' εἰ μέν ἐστιν ὁ συλλογισμὸς ὅτι ἡ ἡδονὴ τἀγαθόν, τἀγαθόν,
εἰ δ' ὅτι ἀγαθόν, ἀγαθόν. οὕτως κἀπὶ τῶν ἄλλων.
10Since the expressions 'pleasure is good' and 'pleasure is the good' are not identical, we must not set out the terms in the same way; but if the syllogism is to prove that pleasure is the good, the term must be 'the good', but if the object is to prove that pleasure is good, the term will be 'good'. Similarly in all other cases.
Book 1,Chapter 41 (49b14–50a4)
Οὐκ ἔστι δὲ ταὐτὸν οὔτ' εἶναι οὔτ' εἰπεῖν, ὅτι ᾧ τὸ Β
15 ὑπάρχει, τούτῳ παντὶ τὸ Α ὑπάρχει, καὶ τὸ εἰπεῖν τὸ ᾧ
παντὶ τὸ Β ὑπάρχει, καὶ τὸ Α παντὶ ὑπάρχει· οὐδὲν γὰρ
κωλύει τὸ Β τῷ Γ ὑπάρχειν, μὴ παντὶ δέ. οἷον ἔστω τὸ Β
καλόν, τὸ δὲ Γ λευκόν. εἰ δὴ λευκῷ τινὶ ὑπάρχει καλόν,
ἀληθὲς εἰπεῖν ὅτι τῷ λευκῷ ὑπάρχει καλόν· ἀλλ' οὐ παντὶ
20 ἴσως. εἰ μὲν οὖν τὸ Α τῷ Β ὑπάρχει, μὴ παντὶ δὲ καθ' οὗ
τὸ Β, οὔτ' εἰ παντὶ τῷ Γ τὸ Β, οὔτ' εἰ μόνον ὑπάρχει,
ἀνάγκη τὸ Α οὐχ ὅτι οὐ παντί, ἀλλ' οὐδ' ὑπάρχειν. εἰ δὲ
καθ' οὗ ἂν τὸ Β λέγηται ἀληθῶς, τούτῳ παντὶ ὑπάρχει,
συμβήσεται τὸ Α, καθ' οὗ παντὸς τὸ Β λέγεται, κατὰ
25 τούτου παντὸς λέγεσθαι. εἰ μέντοι τὸ Α λέγεται καθ' οὗ ἂν
τὸ Β λέγηται κατὰ παντός, οὐδὲν κωλύει τῷ Γ ὑπάρχειν
τὸ Β, μὴ παντὶ δὲ τὸ Α ἢ ὅλως μὴ ὑπάρχειν. ἐν δὴ τοῖς
τρισὶν ὅροις δῆλον ὅτι τὸ καθ' οὗ τὸ Β παντὸς τὸ Α λέγεσθαι
τοῦτ' ἔστι, καθ' ὅσων τὸ Β λέγεται, κατὰ πάντων λέγεσθαι
30 καὶ τὸ Α. καὶ εἰ μὲν κατὰ παντὸς τὸ Β, καὶ τὸ
Α οὕτως· εἰ δὲ μὴ κατὰ παντός, οὐκ ἀνάγκη τὸ Α κατὰ
παντός.
Οὐ δεῖ δ' οἴεσθαι παρὰ τὸ ἐκτίθεσθαί τι συμβαίνειν
ἄτοπον· οὐδὲν γὰρ προσχρώμεθα τῷ τόδε τι εἶναι, ἀλλ'
35 ὥσπερ ὁ γεωμέτρης τὴν ποδιαίαν καὶ εὐθεῖαν τήνδε καὶ
ἀπλατῆ εἶναι λέγει οὐκ οὔσας, ἀλλ' οὐχ οὕτως χρῆται ὡς
ἐκ τούτων συλλογιζόμενος. ὅλως γὰρ ὃ μὴ ἔστιν ὡς ὅλον
πρὸς μέρος καὶ ἄλλο πρὸς τοῦτο ὡς μέρος πρὸς ὅλον, ἐξ
οὐδενὸς τῶν τοιούτων δείκνυσιν ὁ δεικνύων, ὥστε οὐδὲ γίνεται
14It is not the same, either in fact or in speech, that A belongs to all of that to which B belongs, 15and that A belongs to all of that to all of which B belongs: for nothing prevents B from belonging to C, though not to all C: e.g. let B stand for beautiful, and C for white. If beauty belongs to something white, it is true to say that beauty belongs to that which is white; but not 20perhaps to everything that is white. If then A belongs to B, but not to everything of which B is predicated, then whether B belongs to all C or merely belongs to C, it is not necessary that A should belong, I do not say to all C, but even to C at all. But if A belongs to everything of which B is truly stated, it will follow that A can be said of all of that 25of all of which B is said. If however A is said of that of all of which B may be said, nothing prevents B belonging to C, and yet A not belonging to all C or to any C at all. If then we take three terms it is clear that the expression 'A is said of all of which B is said' means this, 'A is said of all the things of which B is said'. 30And if B is said of all of a third term, so also is A: but if B is not said of all of the third term, there is no necessity that A should be said of all of it.
We must not suppose that something absurd results through setting out the terms: for we do not use the existence of this particular thing, but 35imitate the geometrician who says that 'this line a foot long' or 'this straight line' or 'this line without breadth' exists although it does not, but does not use the diagrams in the sense that he reasons from them. For in general, if two things are not related as whole to part and part to whole, the prover does not prove from them, and so no syllogism a is formed.
We must not suppose that something absurd results through setting out the terms: for we do not use the existence of this particular thing, but 35imitate the geometrician who says that 'this line a foot long' or 'this straight line' or 'this line without breadth' exists although it does not, but does not use the diagrams in the sense that he reasons from them. For in general, if two things are not related as whole to part and part to whole, the prover does not prove from them, and so no syllogism a is formed.
50a
1 συλλογισμός. τῷ δ' ἐκτίθεσθαι οὕτω χρώμεθα ὥσπερ καὶ
τῷ αἰσθάνεσθαι, τὸν μανθάνοντ' ἀλέγοντες· οὐ γὰρ οὕτως ὡς
ἄνευ τούτων οὐχ οἷόν τ' ἀποδειχθῆναι, ὥσπερ ἐξ ὧν ὁ συλλογισμός.
1We (I mean the learner) use the process of setting out terms like perception by sense, not as though it were impossible to demonstrate without these illustrative terms, as it is to demonstrate without the premisses of the syllogism.
Book 1,Chapter 42 (50a5–10)
5 Μὴ λανθανέτω δ' ἡμᾶς ὅτι ἐν τῷ αὐτῷ συλλογισμῷ
οὐχ ἅπαντα τὰ συμπεράσματα δι' ἑνὸς σχήματός ἐστιν,
ἀλλὰ τὸ μὲν διὰ τούτου τὸ δὲ δι' ἄλλου. δῆλον οὖν ὅτι καὶ
τὰς ἀναλύσεις οὕτω ποιητέον. ἐπεὶ δ' οὐ πᾶν πρόβλημα ἐν
ἅπαντι σχήματι ἀλλ' ἐν ἑκάστῳ τεταγμένα, φανερὸν ἐκ τοῦ
10 συμπεράσματος ἐν ᾧ σχήματι ζητητέον.
5We should not forget that in the same syllogism not all conclusions are reached through one figure, but one through one figure, another through another. Clearly then we must analyse arguments in accordance with this. Since not every problem is proved in every figure, but certain problems in each figure, it is clear from the 10conclusion in what figure the premisses should be sought.
Book 1,Chapter 43 (50a11–15)
Τούς τε πρὸς ὁρισμὸν τῶν λόγων, ὅσοι πρὸς ἕν τι τυγχάνουσι
διειλεγμένοι τῶν ἐν τῷ ὅρῳ, πρὸς ὃ διείλεκται θετέον
ὅρον, καὶ οὐ τὸν ἅπαντα λόγον· ἧττον γὰρ συμβήσεται
ταράττεσθαι διὰ τὸ μῆκος, οἷον εἰ τὸ ὕδωρ ἔδειξεν ὅτι
15 ὑγρὸν ποτόν, τὸ ποτὸν καὶ τὸ ὕδωρ ὅρους θετέον.
11In reference to those arguments aiming at a definition which have been directed to prove some part of the definition, we must take as a term the point to which the argument has been directed, not the whole definition: for so we shall be less likely to be disturbed by the length of the term: e.g. if a man proves that water is a 15drinkable liquid, we must take as terms drinkable and water.
Book 1,Chapter 44 (50a16–50b4)
Ἔτι δὲ τοὺς ἐξ ὑποθέσεως συλλογισμοὺς οὐ πειρατέον
ἀνάγειν· οὐ γὰρ ἔστιν ἐκ τῶν κειμένων ἀνάγειν. οὐ γὰρ διὰ
συλλογισμοῦ δεδειγμένοι εἰσίν, ἀλλὰ διὰ συνθήκης ὡμολογημένοι
πάντες. οἷον εἰ ὑποθέμενος, ἂν δύναμίς τις μία
20 μὴ ᾖ τῶν ἐναντίων, μηδ' ἐπιστήμην μίαν εἶναι, εἶτα διαλεχθείη
ὅτι οὐκ ἔστι πᾶσα δύναμις τῶν ἐναντίων, οἱονεὶ τοῦ ὑγιεινοῦ
καὶ τοῦ νοσώδους· ἅμα γὰρ ἔσται τὸ αὐτὸ ὑγιεινὸν καὶ νοσῶδες.
ὅτι μὲν οὖν οὐκ ἔστι μία πάντων τῶν ἐναντίων δύναμις,
ἐπιδέδεικται, ὅτι δ' ἐπιστήμη οὐκ ἔστιν, οὐ δέδεικται. καίτοι
25 ὁμολογεῖν ἀναγκαῖον· ἀλλ' οὐκ ἐκ συλλογισμοῦ, ἀλλ' ἐξ
ὑποθέσεως. τοῦτον μὲν οὖν οὐκ ἔστιν ἀναγαγεῖν, ὅτι δ' οὐ μία
δύναμις, ἔστιν· οὗτος γὰρ ἴσως καὶ ἦν συλλογισμός, ἐκεῖνο
δ' ὑπόθεσις.
Ὁμοίως δὲ καὶ ἐπὶ τῶν διὰ τοῦ ἀδυνάτου περαινομένων·
30 οὐδὲ γὰρ τούτους οὐκ ἔστιν ἀναλύειν, ἀλλὰ τὴν μὲν εἰς τὸ ἀδύνατον
ἀπαγωγὴν ἔστι (συλλογισμῷ γὰρ δείκνυται), θάτερον
δ' οὐκ ἔστιν· ἐξ ὑποθέσεως γὰρ περαίνεται. διαφέρουσι δὲ
τῶν προειρημένων ὅτι ἐν ἐκείνοις μὲν δεῖ προδιομολογήσασθαι,
εἰ μέλλει συμφήσειν, οἷον ἂν δειχθῇ μία δύναμις
35 τῶν ἐναντίων, καὶ ἐπιστήμην εἶναι τὴν αὐτήν· ἐνταῦθα δὲ καὶ
μὴ προδιομολογησάμενοι συγχωροῦσι διὰ τὸ φανερὸν εἶναι
τὸ ψεῦδος, οἷον τεθείσης τῆς διαμέτρου συμμέτρου τὸ τὰ
περιττὰ ἴσα εἶναι τοῖς ἀρτίοις.
Πολλοὶ δὲ καὶ ἕτεροι περαίνονται ἐξ ὑποθέσεως, οὓς
40 ἐπισκέψασθαι δεῖ καὶ διασημῆναι καθαρῶς. τίνες μὲν οὖν αἱ
16Further we must not try to reduce hypothetical syllogisms; for with the given premisses it is not possible to reduce them. For they have not been proved by syllogism, but assented to by agreement. For instance if a man should suppose that unless there is one faculty of contraries, there cannot be one science, 20and should then argue that not every faculty is of contraries, e.g. of what is healthy and what is sickly: for the same thing will then be at the same time healthy and sickly. He has shown that there is not one faculty of all contraries, but he has not proved that there is not a science. And yet one must agree. 25But the agreement does not come from a syllogism, but from an hypothesis. This argument cannot be reduced: but the proof that there is not a single faculty can. The latter argument perhaps was a syllogism: but the former was an hypothesis.
The same holds good of arguments which are brought to a conclusion per impossibile. 30These cannot be analysed either; but the reduction to what is impossible can be analysed since it is proved by syllogism, though the rest of the argument cannot, because the conclusion is reached from an hypothesis. But these differ from the previous arguments: for in the former a preliminary agreement must be reached if one is to accept the conclusion; e.g. an agreement that if there is proved to be one faculty of contraries, 35then contraries fall under the same science; whereas in the latter, even if no preliminary agreement has been made, men still accept the reasoning, because the falsity is patent, e.g. the falsity of what follows from the assumption that the diagonal is commensurate, viz. that then odd numbers are equal to evens.
Many other arguments are brought to a conclusion by the help of an hypothesis; 40these we ought to consider and mark out clearly.
The same holds good of arguments which are brought to a conclusion per impossibile. 30These cannot be analysed either; but the reduction to what is impossible can be analysed since it is proved by syllogism, though the rest of the argument cannot, because the conclusion is reached from an hypothesis. But these differ from the previous arguments: for in the former a preliminary agreement must be reached if one is to accept the conclusion; e.g. an agreement that if there is proved to be one faculty of contraries, 35then contraries fall under the same science; whereas in the latter, even if no preliminary agreement has been made, men still accept the reasoning, because the falsity is patent, e.g. the falsity of what follows from the assumption that the diagonal is commensurate, viz. that then odd numbers are equal to evens.
Many other arguments are brought to a conclusion by the help of an hypothesis; 40these we ought to consider and mark out clearly.
50b
1 διαφοραὶ τούτων, καὶ ποσαχῶς γίνεται τὸ ἐξ ὑποθέσεως,
ὕστερον ἐροῦμεν· νῦν δὲ τοσοῦτον ἡμῖν ἔστω φανερόν, ὅτι οὐκ ἔστιν
ἀναλύειν εἰς τὰ σχήματα τοὺς τοιούτους συλλογισμούς. καὶ
δι' ἣν αἰτίαν, εἰρήκαμεν.
1We shall describe in the sequel their differences, and the various ways in which hypothetical arguments are formed: but at present this much must be clear, that it is not possible to resolve such arguments into the figures. And we have explained the reason.
Book 1,Chapter 45 (50b5–51b4)
5 Ὅσα δ' ἐν πλείοσι σχήμασι δείκνυται τῶν προβλημάτων,
ἢν ἐν θατέρῳ συλλογισθῇ, ἔστιν ἀναγαγεῖν τὸν συλλογισμὸν
εἰς θάτερον, οἷον τὸν ἐν τῷ πρώτῳ στερητικὸν εἰς τὸ
δεύτερον, καὶ τὸν ἐν τῷ μέσῳ εἰς τὸ πρῶτον, οὐχ ἅπαντας
δὲ ἀλλ' ἐνίους. ἔσται δὲ φανερὸν ἐν τοῖς ἑπομένοις. εἰ γὰρ
10 τὸ Α μηδενὶ τῷ Β, τὸ δὲ Β παντὶ τῷ Γ, τὸ Α οὐδενὶ τῷ
Γ. οὕτω μὲν οὖν τὸ πρῶτον σχῆμα, ἐὰν δ' ἀντιστραφῇ τὸ
στερητικόν, τὸ μέσον ἔσται· τὸ γὰρ Β τῷ μὲν Α οὐδενί, τῷ
δὲ Γ παντὶ ὑπάρχει. ὁμοίως δὲ καὶ εἰ μὴ καθόλου ἀλλ' ἐν
μέρει ὁ συλλογισμός, οἷον εἰ τὸ μὲν Α μηδενὶ τῷ Β, τὸ δὲ
15 Β τινὶ τῷ Γ· ἀντιστραφέντος γὰρ τοῦ στερητικοῦ τὸ μέσον
ἔσται σχῆμα.
Τῶν δ' ἐν τῷ δευτέρῳ συλλογισμῶν οἱ μὲν καθόλου
ἀναχθήσονται εἰς τὸ πρῶτον, τῶν δ' ἐν μέρει ἅτερος μόνος.
ἔστω γὰρ τὸ Α τῷ μὲν Β μηδενὶ τῷ δὲ Γ παντὶ ὑπάρχον.
20 ἀντιστραφέντος οὖν τοῦ στερητικοῦ τὸ πρῶτον ἔσται σχῆμα· τὸ
μὲν γὰρ Β οὐδενὶ τῷ Α, τὸ δὲ Α παντὶ τῷ Γ ὑπάρξει. ἐὰν
δὲ τὸ κατηγορικὸν ᾖ πρὸς τῷ Β, τὸ δὲ στερητικὸν πρὸς τῷ
Γ, πρῶτον ὅρον θετέον τὸ Γ· τοῦτο γὰρ οὐδενὶ τῷ Α, τὸ δὲ
Α παντὶ τῷ Β· ὥστ' οὐδενὶ τῷ Β τὸ Γ. οὐδ' ἄρα τὸ Β τῷ Γ
25 οὐδενί· ἀντιστρέφει γὰρ τὸ στερητικόν. ἐὰν δ' ἐν μέρει ᾖ ὁ
συλλογισμός, ὅταν μὲν ᾖ τὸ στερητικὸν πρὸς τῷ μείζονι
ἄκρῳ, ἀναχθήσεται εἰς τὸ πρῶτον, οἷον εἰ τὸ Α μηδενὶ τῷ
Β, τῷ δὲ Γ τινί· ἀντιστραφέντος γὰρ τοῦ στερητικοῦ τὸ πρῶτον
ἔσται σχῆμα· τὸ μὲν γὰρ Β οὐδενὶ τῷ Α, τὸ δὲ Α τινὶ
30 τῷ Γ. ὅταν δὲ τὸ κατηγορικόν, οὐκ ἀναλυθήσεται, οἷον εἰ τὸ
Α τῷ μὲν Β παντί, τῷ δὲ Γ οὐ παντί· οὔτε γὰρ δέχεται
ἀντιστροφὴν τὸ Α Β, οὔτε γενομένης ἔσται συλλογισμός.
Πάλιν οἱ μὲν ἐν τῷ τρίτῳ σχήματι οὐκ ἀναλυθήσονται
πάντες εἰς τὸ πρῶτον, οἱ δ' ἐν τῷ πρώτῳ πάντες εἰς τὸ
35 τρίτον. ὑπαρχέτω γὰρ τὸ Α παντὶ τῷ Β, τὸ δὲ Β τινὶ τῷ
Γ. οὐκοῦν ἐπειδὴ ἀντιστρέφει τὸ ἐν μέρει κατηγορικόν, ὑπάρξει
τὸ Γ τινὶ τῷ Β· τὸ δὲ Α παντὶ ὑπῆρχεν, ὥστε γίνεται
τὸ τρίτον σχῆμα. καὶ εἰ στερητικὸς ὁ συλλογισμός, ὡσαύτως·
ἀντιστρέφει γὰρ τὸ ἐν μέρει κατηγορικόν, ὥστε τὸ μὲν
40 Α οὐδενὶ τῷ Β, τὸ δὲ Γ τινὶ ὑπάρξει.
5Whatever problems are proved in more than one figure, if they have been established in one figure by syllogism, can be reduced to another figure, e.g. a negative syllogism in the first figure can be reduced to the second, and a syllogism in the middle figure to the first, not all however but some only. The point will be clear in the sequel. 10If A belongs to no B, and B to all C, then A belongs to no C. Thus the first figure; but if the negative statement is converted, we shall have the middle figure. For B belongs to no A, and to all C. Similarly if the syllogism is not universal but particular, e.g. if A belongs to no B, 15and B to some C. Convert the negative statement and you will have the middle figure.
The universal syllogisms in the second figure can be reduced to the first, but only one of the two particular syllogisms. Let A belong to no B and to all C. 20Convert the negative statement, and you will have the first figure. For B will belong to no A and A to all C. But if the affirmative statement concerns B, and the negative C, C must be made first term. For C belongs to no A, and A to all B: therefore C belongs to no B. B then belongs to no C: 25for the negative statement is convertible.
But if the syllogism is particular, whenever the negative statement concerns the major extreme, reduction to the first figure will be possible, e.g. if A belongs to no B and to some C: convert the negative statement and you will have the first figure. For B will belong to no A and A to some C. 30But when the affirmative statement concerns the major extreme, no resolution will be possible, e.g. if A belongs to all B, but not to all C: for the statement AB does not admit of conversion, nor would there be a syllogism if it did.
Again syllogisms in the third figure cannot all be resolved into the first, though all syllogisms in the first figure can be resolved into the third. 35Let A belong to all B and B to some C. Since the particular affirmative is convertible, C will belong to some B: but A belonged to all B: so that the third figure is formed. Similarly if the syllogism is negative: for the particular affirmative is convertible: therefore 40A will belong to no B, and to some C.
The universal syllogisms in the second figure can be reduced to the first, but only one of the two particular syllogisms. Let A belong to no B and to all C. 20Convert the negative statement, and you will have the first figure. For B will belong to no A and A to all C. But if the affirmative statement concerns B, and the negative C, C must be made first term. For C belongs to no A, and A to all B: therefore C belongs to no B. B then belongs to no C: 25for the negative statement is convertible.
But if the syllogism is particular, whenever the negative statement concerns the major extreme, reduction to the first figure will be possible, e.g. if A belongs to no B and to some C: convert the negative statement and you will have the first figure. For B will belong to no A and A to some C. 30But when the affirmative statement concerns the major extreme, no resolution will be possible, e.g. if A belongs to all B, but not to all C: for the statement AB does not admit of conversion, nor would there be a syllogism if it did.
Again syllogisms in the third figure cannot all be resolved into the first, though all syllogisms in the first figure can be resolved into the third. 35Let A belong to all B and B to some C. Since the particular affirmative is convertible, C will belong to some B: but A belonged to all B: so that the third figure is formed. Similarly if the syllogism is negative: for the particular affirmative is convertible: therefore 40A will belong to no B, and to some C.
51a
1 Τῶν δ' ἐν τῷ τελευταίῳ σχήματι συλλογισμῶν εἷς
μόνος οὐκ ἀναλύεται εἰς τὸ πρῶτον, ὅταν μὴ καθόλου τεθῇ
τὸ στερητικόν, οἱ δ' ἄλλοι πάντες ἀναλύονται. κατηγορείσθω
γὰρ παντὸς τοῦ Γ τὸ Α καὶ τὸ Β· οὐκοῦν ἀντιστρέψει τὸ Γ
5 πρὸς ἑκάτερον ἐπὶ μέρους· ὑπάρχει ἄρα τινὶ τῷ Β. ὥστ'
ἔσται τὸ πρῶτον σχῆμα, εἰ τὸ μὲν Α παντὶ τῷ Γ, τὸ δὲ
Γ τινὶ τῷ Β. καὶ εἰ τὸ μὲν Α παντὶ τῷ Γ, τὸ δὲ Β τινί,
ὁ αὐτὸς λόγος· ἀντιστρέφει γὰρ πρὸς τὸ Β τὸ Γ. ἐὰν δὲ
τὸ μὲν Β παντὶ τῷ Γ, τὸ δὲ Α τινὶ τῷ Γ, πρῶτος ὅρος
10 θετέος τὸ Β· τὸ γὰρ Β παντὶ τῷ Γ, τὸ δὲ Γ τινὶ τῷ Α, ὥστε
τὸ Β τινὶ τῷ Α. ἐπεὶ δ' ἀντιστρέφει τὸ ἐν μέρει, καὶ τὸ Α
τινὶ τῷ Β ὑπάρξει. καὶ εἰ στερητικὸς ὁ συλλογισμός, καθάλου
τῶν ὅρων ὄντων, ὁμοίως ληπτέον. ὑπαρχέτω γὰρ τὸ
Β παντὶ τῷ Γ, τὸ δὲ Α μηδενί· οὐκοῦν τινὶ τῷ Β ὑπάρξει
15 τὸ Γ, τὸ δὲ Α οὐδενὶ τῷ Γ, ὥστ' ἔσται μέσον τὸ Γ. ὁμοίως
δὲ καὶ εἰ τὸ μὲν στερητικὸν καθόλου, τὸ δὲ κατηγορικὸν ἐν
μέρει· τὸ μὲν γὰρ Α οὐδενὶ τῷ Γ, τὸ δὲ Γ τινὶ τῶν Β ὑπάρξει.
ἐὰν δ' ἐν μέρει ληφθῇ τὸ στερητικόν, οὐκ ἔσται ἀνάλυσις,
οἷον εἰ τὸ μὲν Β παντὶ τῷ Γ, τὸ δὲ Α τινὶ μὴ ὑπάρχει·
20 ἀντιστραφέντος γὰρ τοῦ Β Γ ἀμφότεραι αἱ προτάσεις
ἔσονται κατὰ μέρος.
Φανερὸν δὲ καὶ ὅτι πρὸς τὸ ἀναλύειν εἰς ἄλληλα τὰ
σχήματα ἡ πρὸς τῷ ἐλάττονι ἄκρῳ πρότασις ἀντιστρεπτέα
ἐν ἀμφοτέροις τοῖς σχήμασι· ταύτης γὰρ μετατιθεμένης
25 ἡ μετάβασις ἐγίνετο.
Τῶν δ' ἐν τῷ μέσῳ σχήματι ἅτερος μὲν ἀναλύεται,
ἅτερος δ' οὐκ ἀναλύεται, εἰς τὸ τρίτον. ὅταν μὲν γὰρ ᾖ τὸ
καθόλου στερητικόν, ἀναλύεται. εἰ γὰρ τὸ Α μηδενὶ τῷ Β,
τῷ δὲ Γ τινί, ἀμφότερα ὁμοίως ἀντιστρέφει πρὸς τὸ Α,
30 ὥστε τὸ μὲν Β οὐδενὶ τῷ Α, τὸ δὲ Γ τινί· μέσον ἄρα τὸ Α.
ὅταν δὲ τὸ Α παντὶ τῷ Β, τῷ δὲ Γ τινὶ μὴ ὑπάρχῃ, οὐκ
ἔσται ἀνάλυσις· οὐδετέρα γὰρ τῶν προτάσεων ἐκ τῆς ἀντιστροφῆς
καθόλου.
Καὶ οἱ ἐκ τοῦ τρίτου δὲ σχήματος ἀναλυθήσονται εἰς
35 τὸ μέσον, ὅταν ᾖ καθόλου τὸ στερητικόν, οἷον εἰ τὸ Α μηδενὶ
τῷ Γ, τὸ δὲ Β τινὶ ἢ παντί. καὶ γὰρ τὸ Γ τῷ μὲν Α
οὐδενί, τῷ δὲ Β τινὶ ὑπάρξει. ἐὰν δ' ἐπὶ μέρους ᾖ τὸ στερητικόν,
οὐκ ἀναλυθήσεται· οὐ γὰρ δέχεται ἀντιστροφὴν τὸ
ἐν μέρει ἀποφατικόν.
40 Φανερὸν οὖν ὅτι οἱ αὐτοὶ συλλογισμοὶ οὐκ ἀναλύονται
ἐν τούτοις τοῖς σχήμασιν οἵπερ οὐδ' εἰς τὸ πρῶτον ἀνελύοντο,
1Of the syllogisms in the last figure one only cannot be resolved into the first, viz. when the negative statement is not universal: all the rest can be resolved. Let A and B be affirmed of all C: then C can be converted 5partially with either A or B: C then belongs to some B. Consequently we shall get the first figure, if A belongs to all C, and C to some of the Bs. If A belongs to all C and B to some C, the argument is the same: for B is convertible in reference to C. But if B belongs to all C and A to some C, 10the first term must be B: for B belongs to all C, and C to some A, therefore B belongs to some A. But since the particular statement is convertible, A will belong to some B. If the syllogism is negative, when the terms are universal we must take them in a similar way. Let B belong to all C, and A to no C: then C will belong to some B, 15and A to no C; and so C will be middle term. Similarly if the negative statement is universal, the affirmative particular: for A will belong to no C, and C to some of the Bs. But if the negative statement is particular, no resolution will be possible, e.g. if B belongs to all C, and A not belong to some C: 20convert the statement BC and both premisses will be particular.
It is clear that in order to resolve the figures into one another the premiss which concerns the minor extreme must be converted in both the figures: for when this premiss is altered, 25the transition to the other figure is made.
One of the syllogisms in the middle figure can, the other cannot, be resolved into the third figure. Whenever the universal statement is negative, resolution is possible. For if A belongs to no B and to some C, both B and C alike are convertible in relation to A, 30so that B belongs to no A and C to some A. A therefore is middle term. But when A belongs to all B, and not to some C, resolution will not be possible: for neither of the premisses is universal after conversion.
Syllogisms in the third figure can be resolved into the middle figure, 35whenever the negative statement is universal, e.g. if A belongs to no C, and B to some or all C. For C then will belong to no A and to some B. But if the negative statement is particular, no resolution will be possible: for the particular negative does not admit of conversion.
40It is clear then that the same syllogisms cannot be resolved in these figures which could not be resolved into the first figure, and that when syllogisms are reduced to the first figure these alone are confirmed by reduction to what is impossible.
It is clear that in order to resolve the figures into one another the premiss which concerns the minor extreme must be converted in both the figures: for when this premiss is altered, 25the transition to the other figure is made.
One of the syllogisms in the middle figure can, the other cannot, be resolved into the third figure. Whenever the universal statement is negative, resolution is possible. For if A belongs to no B and to some C, both B and C alike are convertible in relation to A, 30so that B belongs to no A and C to some A. A therefore is middle term. But when A belongs to all B, and not to some C, resolution will not be possible: for neither of the premisses is universal after conversion.
Syllogisms in the third figure can be resolved into the middle figure, 35whenever the negative statement is universal, e.g. if A belongs to no C, and B to some or all C. For C then will belong to no A and to some B. But if the negative statement is particular, no resolution will be possible: for the particular negative does not admit of conversion.
40It is clear then that the same syllogisms cannot be resolved in these figures which could not be resolved into the first figure, and that when syllogisms are reduced to the first figure these alone are confirmed by reduction to what is impossible.
51b
1 καὶ ὅτι εἰς τὸ πρῶτον σχῆμα τῶν συλλογισμῶν ἀναγομένων
οὗτοι μόνοι διὰ τοῦ ἀδυνάτου περαίνονται.
Πῶς μὲν οὖν δεῖ τοὺς συλλογισμοὺς ἀνάγειν, καὶ ὅτι
ἀναλύεται τὰ σχήματα εἰς ἄλληλα, φανερὸν ἐκ τῶν εἰρημένων.
1It is clear from what we have said how we ought to reduce syllogisms, and that the figures may be resolved into one another.
Book 1,Chapter 46 (51b5–52b34)
5 διαφέρει δέ τι ἐν τῷ κατασκευάζειν ἢ ἀνασκευάζειν
τὸ ὑπολαμβάνειν ἢ ταὐτὸν ἢ ἕτερον σημαίνειν τὸ μὴ
εἶναι τοδὶ καὶ εἶναι μὴ τοῦτο, οἷον τὸ μὴ εἶναι λευκὸν τῷ
εἶναι μὴ λευκόν. οὐ γὰρ ταὐτὸν σημαίνει, οὐδ' ἔστιν ἀπόφασις
τοῦ εἶναι λευκὸν τὸ εἶναι μὴ λευκόν, ἀλλὰ τὸ μὴ
10 εἶναι λευκόν. λόγος δὲ τούτου ὅδε. ὁμοίως γὰρ ἔχει τὸ δύναται
βαδίζειν πρὸς τὸ δύναται οὐ βαδίζειν τῷ ἔστι λευκόν
πρὸς τὸ ἔστιν οὐ λευκόν, καὶ ἐπίσταται τἀγαθόν πρὸς τὸ
ἐπίσταται τὸ οὐκ ἀγαθόν. τὸ γὰρ ἐπίσταται τἀγαθόν ἢ ἔστιν
ἐπιστάμενος τἀγαθόν οὐδὲν διαφέρει, οὐδὲ τὸ δύναται βαδίζειν
15 ἢ ἔστι δυνάμενος βαδίζειν· ὥστε καὶ τὰ ἀντικείμενα,
οὐ δύναται βαδίζειν—οὐκ ἔστι δυνάμενος βαδίζειν. εἰ οὖν τὸ
οὐκ ἔστι δυνάμενος βαδίζειν ταὐτὸ σημαίνει καὶ ἔστι δυνάμενος
οὐ βαδίζειν ἢ μὴ βαδίζειν, ταῦτά γε ἅμα ὑπάρξει
ταὐτῷ (ὁ γὰρ αὐτὸς δύναται καὶ βαδίζειν καὶ μὴ βαδίζειν,
20 καὶ ἐπιστήμων τἀγαθοῦ καὶ τοῦ μὴ ἀγαθοῦ ἐστί), φάσις
δὲ καὶ ἀπόφασις οὐχ ὑπάρχουσιν αἱ ἀντικείμεναι ἅμα τῷ
αὐτῷ. ὥσπερ οὖν οὐ ταὐτό ἐστι τὸ μὴ ἐπίστασθαι τἀγαθὸν
καὶ ἐπίστασθαι τὸ μὴ ἀγαθόν, οὐδ' εἶναι μὴ ἀγαθὸν καὶ
μὴ εἶναι ἀγαθὸν ταὐτόν. τῶν γὰρ ἀνάλογον ἐὰν θάτερα
25 ᾖ ἕτερα, καὶ θάτερα. οὐδὲ τὸ εἶναι μὴ ἴσον καὶ τὸ μὴ εἶναι
ἴσον· τῷ μὲν γὰρ ὑπόκειταί τι, τῷ ὄντι μὴ ἴσῳ, καὶ
τοῦτ' ἔστι τὸ ἄνισον, τῷ δ' οὐδέν. διόπερ ἴσον μὲν ἢ ἄνισον οὐ
πᾶν, ἴσον δ' ἢ οὐκ ἴσον πᾶν. ἔτι τὸ ἔστιν οὐ λευκὸν ξύλον
καὶ οὐκ ἔστι λευκὸν ξύλον οὐχ ἅμα ὑπάρχει. εἰ γάρ ἐστι
30 ξύλον οὐ λευκόν, ἔσται ξύλον· τὸ δὲ μὴ ὂν λευκὸν ξύλον οὐκ
ἀνάγκη ξύλον εἶναι. ὥστε φανερὸν ὅτι οὐκ ἔστι τοῦ ἔστιν ἀγαθόν
τὸ ἔστιν οὐκ ἀγαθόν ἀπόφασις. εἰ οὖν κατὰ παντὸς ἑνὸς
ἢ φάσις ἢ ἀπόφασις ἀληθής, εἰ μὴ ἔστιν ἀπόφασις, δῆλον
ὡς κατάφασις ἄν πως εἴη. καταφάσεως δὲ πάσης
35 ἀπόφασις ἔστιν· καὶ ταύτης ἄρα τὸ οὐκ ἔστιν οὐκ ἀγαθόν.
Ἔχει δὲ τάξιν τήνδε πρὸς ἄλληλα. ἔστω τὸ εἶναι ἀγαθὸν
ἐφ' οὗ Α, τὸ δὲ μὴ εἶναι ἀγαθὸν ἐφ' οὗ Β, τὸ δὲ εἶναι
μὴ ἀγαθὸν ἐφ' οὗ Γ, ὑπὸ τὸ Β, τὸ δὲ μὴ εἶναι μὴ ἀγαθὸν
ἐφ' οὗ Δ, ὑπὸ τὸ Α. παντὶ δὴ ὑπάρξει ἢ τὸ Α ἢ τὸ
40 Β, καὶ οὐδενὶ τῷ αὐτῷ· καὶ ἢ τὸ Γ ἢ τὸ Δ, καὶ οὐδενὶ
τῷ αὐτῷ. καὶ ᾧ τὸ Γ, ἀνάγκη τὸ Β παντὶ ὑπάρχειν (εἰ
5In establishing or refuting, it makes some difference whether we suppose the expressions 'not to be this' and 'to be not-this' are identical or different in meaning, e.g. 'not to be white' and 'to be not-white'. For they do not mean the same thing, nor is 'to be not-white' the negation of 'to be white', but 'not to be white'. 10The reason for this is as follows. The relation of 'he can walk' to 'he can not-walk' is similar to the relation of 'it is white' to 'it is not-white'; so is that of 'he knows what is good' to 'he knows what is not-good'. For there is no difference between the expressions 'he knows what is good' and 'he is knowing what is good', or 'he can walk' and 15'he is able to walk': therefore there is no difference between their contraries 'he cannot walk'-'he is not able to walk'. If then 'he is not able to walk' means the same as 'he is able not to walk', capacity to walk and incapacity to walk will belong at the same time to the same person (for the same man can both walk and not-walk, 20and is possessed of knowledge of what is good and of what is not-good), but an affirmation and a denial which are opposed to one another do not belong at the same time to the same thing. As then 'not to know what is good' is not the same as 'to know what is not good', so 'to be not-good' is not the same as 'not to be good'. For when two pairs correspond, if the one pair are different from one another, 25the other pair also must be different. Nor is 'to be not-equal' the same as 'not to be equal': for there is something underlying the one, viz. that which is not-equal, and this is the unequal, but there is nothing underlying the other. Wherefore not everything is either equal or unequal, but everything is equal or is not equal. Further the expressions 'it is a not-white log' and 'it is not a white log' do not imply one another's truth. For if 'it is a not-white log', 30it must be a log: but that which is not a white log need not be a log at all. Therefore it is clear that 'it is not-good' is not the denial of 'it is good'. If then every single statement may truly be said to be either an affirmation or a negation, if it is not a negation clearly it must in a sense be an affirmation. 35But every affirmation has a corresponding negation. The negation then of 'it is not-good' is 'it is not not-good'. The relation of these statements to one another is as follows. Let A stand for 'to be good', B for 'not to be good', let C stand for 'to be not-good' and be placed under B, and let D stand for not to be not-good' and be placed under A. 40Then either A or B will belong to everything, but they will never belong to the same thing; and either C or D will belong to everything, but they will never belong to the same thing.
52a
1 γὰρ ἀληθὲς εἰπεῖν ὅτι ἐστὶν οὐ λευκόν, καὶ ὅτι οὐκ ἔστι λευκὸν
ἀληθές· ἀδύνατον γὰρ ἅμα εἶναι λευκὸν καὶ εἶναι μὴ λευκόν,
ἢ εἶναι ξύλον οὐ λευκὸν καὶ εἶναι ξύλον λευκόν, ὥστ'
εἰ μὴ ἡ κατάφασις, ἡ ἀπόφασις ὑπάρξει), τῷ δὲ Β τὸ Γ
5 οὐκ ἀεί (ὃ γὰρ ὅλως μὴ ξύλον, οὐδὲ ξύλον ἔσται οὐ λευκόν).
ἀνάπαλιν τοίνυν, ᾧ τὸ Α, τὸ Δ παντί (ἢ γὰρ τὸ Γ ἢ τὸ
Δ· ἐπεὶ δ' οὐχ οἷόν τε ἅμα εἶναι μὴ λευκὸν καὶ λευκόν,
τὸ Δ ὑπάρξει· κατὰ γὰρ τοῦ ὄντος λευκοῦ ἀληθὲς εἰπεῖν
ὅτι οὐκ ἔστιν οὐ λευκόν), κατὰ δὲ τοῦ Δ οὐ παντὸς τὸ Α (κατὰ
10 γὰρ τοῦ ὅλως μὴ ὄντος ξύλου οὐκ ἀληθὲς τὸ Α εἰπεῖν, ὡς
ἔστι ξύλον λευκόν, ὥστε τὸ Δ ἀληθές, τὸ δ' Α οὐκ ἀληθές,
ὅτι ξύλον λευκόν). δῆλον δ' ὅτι καὶ τὸ Α Γ οὐδενὶ
τῷ αὐτῷ καὶ τὸ Β καὶ τὸ Δ ἐνδέχεται τινὶ τῷ αὐτῷ
ὑπάρξαι.
15 Ὁμοίως δ' ἔχουσι καὶ αἱ στερήσεις πρὸς τὰς κατηγορίας
ταύτῃ τῇ θέσει. ἴσον ἐφ' οὗ τὸ Α, οὐκ ἴσον ἐφ' οὗ
Β, ἄνισον ἐφ' οὗ Γ, οὐκ ἄνισον ἐφ' οὗ Δ.
Καὶ ἐπὶ πολλῶν δέ, ὧν τοῖς μὲν ὑπάρχει τοῖς δ' οὐχ
ὑπάρχει ταὐτόν, ἡ μὲν ἀπόφασις ὁμοίως ἀληθεύοιτ' ἄν, ὅτι
20 οὐκ ἔστι λευκὰ πάντα ἢ ὅτι οὐκ ἔστι λευκὸν ἕκαστον· ὅτι δ'
ἐστὶν οὐ λευκὸν ἕκαστον ἢ πάντα ἐστὶν οὐ λευκά, ψεῦδος.
ὁμοίως δὲ καὶ τοῦ ἔστι πᾶν ζῷον λευκόν οὐ τὸ ἔστιν οὐ λευκὸν
ἅπαν ζῷον ἀπόφασις (ἄμφω γὰρ ψευδεῖς), ἀλλὰ τὸ
οὐκ ἔστι πᾶν ζῷον λευκόν. Ἐπεὶ δὲ δῆλον ὅτι ἕτερον σημαίνει
25 τὸ ἔστιν οὐ λευκόν καὶ οὐκ ἔστι λευκόν, καὶ τὸ μὲν κατάφασις
τὸ δ' ἀπόφασις, φανερὸν ὡς οὐχ ὁ αὐτὸς τρόπος
τοῦ δεικνύναι ἑκάτερον, οἷον ὅτι ὃ ἂν ᾖ ζῷον οὐκ ἔστι λευκὸν
ἢ ἐνδέχεται μὴ εἶναι λευκόν, καὶ ὅτι ἀληθὲς εἰπεῖν μὴ
λευκόν· τοῦτο γάρ ἐστιν εἶναι μὴ λευκόν. ἀλλὰ τὸ μὲν
30 ἀληθὲς εἰπεῖν ἔστι λευκόν εἴτε μὴ λευκόν ὁ αὐτὸς τρόπος·
κατασκευαστικῶς γὰρ ἄμφω διὰ τοῦ πρώτου δείκνυται σχήματος·
τὸ γὰρ ἀληθὲς τῷ ἔστιν ὁμοίως τάττεται· τοῦ γὰρ
ἀληθὲς εἰπεῖν λευκὸν οὐ τὸ ἀληθὲς εἰπεῖν μὴ λευκὸν ἀπόφασις,
ἀλλὰ τὸ μὴ ἀληθὲς εἰπεῖν λευκόν. εἰ δὴ ἔσται ἀληθὲς
35 εἰπεῖν ὃ ἂν ᾖ ἄνθρωπος μουσικὸν εἶναι ἢ μὴ μουσικὸν εἶναι,
ὃ ἂν ᾖ ζῷον ληπτέον ἢ εἶναι μουσικὸν ἢ εἶναι μὴ μουσικόν,
καὶ δέδεικται. τὸ δὲ μὴ εἶναι μουσικὸν ὃ ἂν ᾖ ἄνθρωπος, ἀνασκευαστικῶς
δείκνυται κατὰ τοὺς εἰρημένους τρόπους τρεῖς.
Ἁπλῶς δ' ὅταν οὕτως ἔχῃ τὸ Α καὶ τὸ Β ὥσθ' ἅμα
40 μὲν τῷ αὐτῷ μὴ ἐνδέχεσθαι, παντὶ δὲ ἐξ ἀνάγκης θάτερον,
1And B must belong to everything to which C belongs. For if it is true to say 'it is a not-white', it is true also to say 'it is not white': for it is impossible that a thing should simultaneously be white and be not-white, or be a not-white log and be a white log; consequently if the affirmation does not belong, the denial must belong. But C does not always belong to B: 5for what is not a log at all, cannot be a not-white log either. On the other hand D belongs to everything to which A belongs. For either C or D belongs to everything to which A belongs. But since a thing cannot be simultaneously not-white and white, D must belong to everything to which A belongs. For of that which is white it is true to say that it is not not-white. But A is not true of all D. 10For of that which is not a log at all it is not true to say A, viz. that it is a white log. Consequently D is true, but A is not true, i.e. that it is a white log. It is clear also that A and C cannot together belong to the same thing, and that B and D may possibly belong to the same thing.
15Privative terms are similarly related positive ter terms respect of this arrangement. Let A stand for 'equal', B for 'not equal', C for 'unequal', D for 'not unequal'.
In many things also, to some of which something belongs which does not belong to others, the negation may be true in a similar way, 20viz. that all are not white or that each is not white, while that each is not-white or all are not-white is false. Similarly also 'every animal is not-white' is not the negation of 'every animal is white' (for both are false): the proper negation is 'every animal is not white'. Since it is clear that 'it is not-white' 25and 'it is not white' mean different things, and one is an affirmation, the other a denial, it is evident that the method of proving each cannot be the same, e.g. that whatever is an animal is not white or may not be white, and that it is true to call it not-white; for this means that it is not-white. 30But we may prove that it is true to call it white or not-white in the same way for both are proved constructively by means of the first figure. For the expression 'it is true' stands on a similar footing to 'it is'. For the negation of 'it is true to call it white' is not 'it is true to call it not-white' but 'it is not true to call it white'. If then it is to be true 35to say that whatever is a man is musical or is not-musical, we must assume that whatever is an animal either is musical or is not-musical; and the proof has been made. That whatever is a man is not musical is proved destructively in the three ways mentioned.
In general whenever A and B are such that 40they cannot belong at the same time to the same thing, and one of the two necessarily belongs to everything, and again C and D are related in the same way, and A follows C but the relation cannot be reversed, then D must follow B and the relation cannot be reversed.
15Privative terms are similarly related positive ter terms respect of this arrangement. Let A stand for 'equal', B for 'not equal', C for 'unequal', D for 'not unequal'.
In many things also, to some of which something belongs which does not belong to others, the negation may be true in a similar way, 20viz. that all are not white or that each is not white, while that each is not-white or all are not-white is false. Similarly also 'every animal is not-white' is not the negation of 'every animal is white' (for both are false): the proper negation is 'every animal is not white'. Since it is clear that 'it is not-white' 25and 'it is not white' mean different things, and one is an affirmation, the other a denial, it is evident that the method of proving each cannot be the same, e.g. that whatever is an animal is not white or may not be white, and that it is true to call it not-white; for this means that it is not-white. 30But we may prove that it is true to call it white or not-white in the same way for both are proved constructively by means of the first figure. For the expression 'it is true' stands on a similar footing to 'it is'. For the negation of 'it is true to call it white' is not 'it is true to call it not-white' but 'it is not true to call it white'. If then it is to be true 35to say that whatever is a man is musical or is not-musical, we must assume that whatever is an animal either is musical or is not-musical; and the proof has been made. That whatever is a man is not musical is proved destructively in the three ways mentioned.
In general whenever A and B are such that 40they cannot belong at the same time to the same thing, and one of the two necessarily belongs to everything, and again C and D are related in the same way, and A follows C but the relation cannot be reversed, then D must follow B and the relation cannot be reversed.
52b
1 καὶ πάλιν τὸ Γ καὶ τὸ Δ ὡσαύτως, ἕπηται δὲ τῷ Γ
τὸ Α καὶ μὴ ἀντιστρέφῃ, καὶ τῷ Β τὸ Δ ἀκολουθήσει καὶ
οὐκ ἀντιστρέψει· καὶ τὸ μὲν Α καὶ Δ ἐνδέχεται τῷ αὐτῷ,
τὸ δὲ Β καὶ Γ οὐκ ἐνδέχεται. πρῶτον μὲν οὖν ὅτι τῷ Β
5 τὸ Δ ἕπεται, ἐνθένδε φανερόν. ἐπεὶ γὰρ παντὶ τῶν Γ Δ
θάτερον ἐξ ἀνάγκης, ᾧ δὲ τὸ Β, οὐκ ἐνδέχεται τὸ Γ διὰ
τὸ συνεπιφέρειν τὸ Α, τὸ δὲ Α καὶ Β μὴ ἐνδέχεσθαι τῷ
αὐτῷ, φανερὸν ὅτι τὸ Δ ἀκολουθήσει. πάλιν ἐπεὶ τῷ Α τὸ
Γ οὐκ ἀντιστρέφει, παντὶ δὲ τὸ Γ ἢ τὸ Δ, ἐνδέχεται τὸ Α
10 καὶ τὸ Δ τῷ αὐτῷ ὑπάρχειν. τὸ δέ γε Β καὶ τὸ Γ οὐκ
ἐνδέχεται διὰ τὸ συνακολουθεῖν τῷ Γ τὸ Α· συμβαίνει γάρ
τι ἀδύνατον. φανερὸν οὖν ὅτι οὐδὲ τῷ Δ τὸ Β ἀντιστρέφει,
ἐπείπερ ἐγχωρεῖ ἅμα τὸ Δ καὶ τὸ Α ὑπάρχειν.
Συμβαίνει δ' ἐνίοτε καὶ ἐν τῇ τοιαύτῃ τάξει τῶν ὅρων
15 ἀπατᾶσθαι διὰ τὸ μὴ τὰ ἀντικείμενα λαμβάνειν ὀρθῶς ὧν
ἀνάγκη παντὶ θάτερον ὑπάρχειν· οἷον εἰ τὸ Α καὶ τὸ Β μὴ
ἐνδέχεται ἅμα τῷ αὐτῷ, ἀνάγκη δ' ὑπάρχειν, ᾧ μὴ θάτερον,
θάτερον, καὶ πάλιν τὸ Γ καὶ τὸ Δ ὡσαύτως, ᾧ δὲ
τὸ Γ, παντὶ ἕπεται τὸ Α. συμβήσεται γὰρ ᾧ τὸ Δ, τὸ Β
20 ὑπάρχειν ἐξ ἀνάγκης, ὅπερ ἐστὶ ψεῦδος. εἰλήφθω γὰρ ἀπόφασις
τῶν Α Β ἡ ἐφ' ᾧ Ζ, καὶ πάλιν τῶν Γ Δ ἡ ἐφ'
ᾧ Θ. ἀνάγκη δὴ παντὶ ἢ τὸ Α ἢ τὸ Ζ· ἢ γὰρ τὴν φάσιν
ἢ τὴν ἀπόφασιν. καὶ πάλιν ἢ τὸ Γ ἢ τὸ Θ· φάσις
γὰρ καὶ ἀπόφασις. καὶ ᾧ τὸ Γ, παντὶ τὸ Α ὑπόκειται.
25 ὥστε ᾧ τὸ Ζ, παντὶ τὸ Θ. πάλιν ἐπεὶ τῶν Ζ Β παντὶ θάτερον
καὶ τῶν Θ Δ ὡσαύτως, ἀκολουθεῖ δὲ τῷ Ζ τὸ Θ,
καὶ τῷ Δ ἀκολουθήσει τὸ Β· τοῦτο γὰρ ἴσμεν. εἰ ἄρα τῷ
Γ τὸ Α, καὶ τῷ Δ τὸ Β. τοῦτο δὲ ψεῦδος· ἀνάπαλιν γὰρ
ἦν ἐν τοῖς οὕτως ἔχουσιν ἡ ἀκολούθησις. οὐ γὰρ ἴσως ἀνάγκη
30 παντὶ τὸ Α ἢ τὸ Ζ, οὐδὲ τὸ Ζ ἢ τὸ Β· οὐ γάρ ἐστιν ἀπόφασις
τοῦ Α τὸ Ζ. τοῦ γὰρ ἀγαθοῦ τὸ οὐκ ἀγαθὸν ἀπόφασις·
οὐ ταὐτὸ δ' ἐστὶ τὸ οὐκ ἀγαθὸν τῷ οὔτ' ἀγαθὸν οὔτ'
οὐκ ἀγαθόν. ὁμοίως δὲ καὶ ἐπὶ τῶν Γ Δ· αἱ γὰρ ἀποφάσεις
αἱ εἰλημμέναι δύο εἰσίν.
1And A and D may belong to the same thing, but B and C cannot. First it is clear from the following consideration 5that D follows B. For since either C or D necessarily belongs to everything; and since C cannot belong to that to which B belongs, because it carries A along with it and A and B cannot belong to the same thing; it is clear that D must follow B. Again since C does not reciprocate with but A, but C or D belongs to everything, it is possible 10that A and D should belong to the same thing. But B and C cannot belong to the same thing, because A follows C; and so something impossible results. It is clear then that B does not reciprocate with D either, since it is possible that D and A should belong at the same time to the same thing.
It results sometimes even in such an arrangement of terms 15that one is deceived through not apprehending the opposites rightly, one of which must belong to everything, e.g. we may reason that 'if A and B cannot belong at the same time to the same thing, but it is necessary that one of them should belong to whatever the other does not belong to: and again C and D are related in the same way, and follows everything which C follows: it will result that 20B belongs necessarily to everything to which D belongs': but this is false. 'Assume that F stands for the negation of A and B, and again that H stands for the negation of C and D. It is necessary then that either A or F should belong to everything: for either the affirmation or the denial must belong. And again either C or H must belong to everything: for they are related as affirmation and denial. And ex hypothesi A belongs to everything ever thing to which C belongs. 25Therefore H belongs to everything to which F belongs. Again since either F or B belongs to everything, and similarly either H or D, and since H follows F, B must follow D: for we know this. If then A follows C, B must follow D'. But this is false: for as we proved the sequence is reversed in terms so constituted. The fallacy arises because perhaps it is not necessary 30that A or F should belong to everything, or that F or B should belong to everything: for F is not the denial of A. For not good is the negation of good: and not-good is not identical with 'neither good nor not-good'. Similarly also with C and D. For two negations have been assumed in respect to one term.
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It results sometimes even in such an arrangement of terms 15that one is deceived through not apprehending the opposites rightly, one of which must belong to everything, e.g. we may reason that 'if A and B cannot belong at the same time to the same thing, but it is necessary that one of them should belong to whatever the other does not belong to: and again C and D are related in the same way, and follows everything which C follows: it will result that 20B belongs necessarily to everything to which D belongs': but this is false. 'Assume that F stands for the negation of A and B, and again that H stands for the negation of C and D. It is necessary then that either A or F should belong to everything: for either the affirmation or the denial must belong. And again either C or H must belong to everything: for they are related as affirmation and denial. And ex hypothesi A belongs to everything ever thing to which C belongs. 25Therefore H belongs to everything to which F belongs. Again since either F or B belongs to everything, and similarly either H or D, and since H follows F, B must follow D: for we know this. If then A follows C, B must follow D'. But this is false: for as we proved the sequence is reversed in terms so constituted. The fallacy arises because perhaps it is not necessary 30that A or F should belong to everything, or that F or B should belong to everything: for F is not the denial of A. For not good is the negation of good: and not-good is not identical with 'neither good nor not-good'. Similarly also with C and D. For two negations have been assumed in respect to one term.
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