Ross (OCT, 1964) · Mure (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 (71a1–71b8)
71a
1 Πᾶσα διδασκαλία καὶ πᾶσα μάθησις διανοητικὴ ἐκ προϋπαρχούσης
γίνεται γνώσεως. φανερὸν δὲ τοῦτο θεωροῦσιν ἐπὶ
πασῶν· αἵ τε γὰρ μαθηματικαὶ τῶν ἐπιστημῶν διὰ τούτου
τοῦ τρόπου παραγίνονται καὶ τῶν ἄλλων ἑκάστη τεχνῶν.
5 ὁμοίως δὲ καὶ περὶ τοὺς λόγους οἵ τε διὰ συλλογισμῶν καὶ
οἱ δι' ἐπαγωγῆς· ἀμφότεροι γὰρ διὰ προγινωσκομένων ποιοῦνται
τὴν διδασκαλίαν, οἱ μὲν λαμβάνοντες ὡς παρὰ ξυνιέντων,
οἱ δὲ δεικνύντες τὸ καθόλου διὰ τοῦ δῆλον εἶναι τὸ καθ'
ἕκαστον. ὡς δ' αὔτως καὶ οἱ ῥητορικοὶ συμπείθουσιν· ἢ γὰρ
10 διὰ παραδειγμάτων, ὅ ἐστιν ἐπαγωγή, ἢ δι' ἐνθυμημάτων,
ὅπερ ἐστὶ συλλογισμός. διχῶς δ' ἀναγκαῖον προγινώσκειν·
τὰ μὲν γάρ, ὅτι ἔστι, προϋπολαμβάνειν ἀναγκαῖον, τὰ δέ,
τί τὸ λεγόμενόν ἐστι, ξυνιέναι δεῖ, τὰ δ' ἄμφω, οἷον ὅτι
μὲν ἅπαν ἢ φῆσαι ἢ ἀποφῆσαι ἀληθές, ὅτι ἔστι, τὸ δὲ τρίγωνον,
15 ὅτι τοδὶ σημαίνει, τὴν δὲ μονάδα ἄμφω, καὶ τί σημαίνει
καὶ ὅτι ἔστιν· οὐ γὰρ ὁμοίως τούτων ἕκαστον δῆλον
ἡμῖν. Ἔστι δὲ γνωρίζειν τὰ μὲν πρότερον γνωρίσαντα, τῶν δὲ
καὶ ἅμα λαμβάνοντα τὴν γνῶσιν, οἷον ὅσα τυγχάνει ὄντα
ὑπὸ τὸ καθόλου οὗ ἔχει τὴν γνῶσιν. ὅτι μὲν γὰρ πᾶν τρίγωνον
20 ἔχει δυσὶν ὀρθαῖς ἴσας, προῄδει· ὅτι δὲ τόδε τὸ ἐν τῷ
ἡμικυκλίῳ τρίγωνόν ἐστιν, ἅμα ἐπαγόμενος ἐγνώρισεν. (ἐνίων
γὰρ τοῦτον τὸν τρόπον ἡ μάθησίς ἐστι, καὶ οὐ διὰ τοῦ μέσου
τὸ ἔσχατον γνωρίζεται, ὅσα ἤδη τῶν καθ' ἕκαστα τυγχάνει
ὄντα καὶ μὴ καθ' ὑποκειμένου τινός.) πρὶν δ' ἐπαχθῆναι
25 ἢ λαβεῖν συλλογισμὸν τρόπον μέν τινα ἴσως φατέον ἐπίστασθαι,
τρόπον δ' ἄλλον οὔ. ὃ γὰρ μὴ ᾔδει εἰ ἔστιν ἁπλῶς,
τοῦτο πῶς ᾔδει ὅτι δύο ὀρθὰς ἔχει ἁπλῶς; ἀλλὰ δῆλον ὡς
ὡδὶ μὲν ἐπίσταται, ὅτι καθόλου ἐπίσταται, ἁπλῶς δ' οὐκ
ἐπίσταται. εἰ δὲ μή, τὸ ἐν τῷ Μένωνι ἀπόρημα συμβήσεται·
30 ἢ γὰρ οὐδὲν μαθήσεται ἢ ἃ οἶδεν. οὐ γὰρ δή, ὥς γέ τινες
ἐγχειροῦσι λύειν, λεκτέον. ἆρ' οἶδας ἅπασαν δυάδα ὅτι
ἀρτία ἢ οὔ; φήσαντος δὲ προήνεγκάν τινα δυάδα ἣν οὐκ ᾤετ'
εἶναι, ὥστ' οὐδ' ἀρτίαν. λύουσι γὰρ οὐ φάσκοντες εἰδέναι πᾶσαν
δυάδα ἀρτίαν οὖσαν, ἀλλ' ἣν ἴσασιν ὅτι δυάς. καίτοι
1All instruction given or received by way of argument proceeds from pre-existent knowledge. This becomes evident upon a survey of all the species of such instruction. The mathematical sciences and all other speculative disciplines are acquired in this way, 5and so are the two forms of dialectical reasoning, syllogistic and inductive; for each of these latter make use of old knowledge to impart new, the syllogism assuming an audience that accepts its premisses, induction exhibiting the universal as implicit in the clearly known particular. Again, the persuasion exerted by rhetorical arguments is in principle the same, since they 10use either example, a kind of induction, or enthymeme, a form of syllogism.
The pre-existent knowledge required is of two kinds. In some cases admission of the fact must be assumed, in others comprehension of the meaning of the term used, and sometimes both assumptions are essential. Thus, we assume that every predicate can be either truly affirmed or truly denied of any subject, and that 'triangle' 15means so and so; as regards 'unit' we have to make the double assumption of the meaning of the word and the existence of the thing. The reason is that these several objects are not equally obvious to us. Recognition of a truth may in some cases contain as factors both previous knowledge and also knowledge acquired simultaneously with that recognition-knowledge, this latter, of the particulars actually falling under the universal and therein already virtually known. For example, the student knew beforehand that the angles of every triangle 20are equal to two right angles; but it was only at the actual moment at which he was being led on to recognize this as true in the instance before him that he came to know 'this figure inscribed in the semicircle' to be a triangle. For some things (viz. the singulars finally reached which are not predicable of anything else as subject) are only learnt in this way, i.e. there is here no recognition through a middle of a minor term as subject to a major. Before he was led on to recognition 25or before he actually drew a conclusion, we should perhaps say that in a manner he knew, in a manner not.
If he did not in an unqualified sense of the term know the existence of this triangle, how could he know without qualification that its angles were equal to two right angles? No: clearly he knows not without qualification but only in the sense that he knows universally. If this distinction is not drawn, we are faced with the dilemma in the Meno: 30either a man will learn nothing or what he already knows; for we cannot accept the solution which some people offer. A man is asked, 'Do you, or do you not, know that every pair is even?' He says he does know it. The questioner then produces a particular pair, of the existence, and so a fortiori of the evenness, of which he was unaware. The solution which some people offer is to assert that they do not know that every pair is even, but only that everything which they know to be a pair is even: yet what they know to be even is that of which they have demonstrated evenness, i.e.
The pre-existent knowledge required is of two kinds. In some cases admission of the fact must be assumed, in others comprehension of the meaning of the term used, and sometimes both assumptions are essential. Thus, we assume that every predicate can be either truly affirmed or truly denied of any subject, and that 'triangle' 15means so and so; as regards 'unit' we have to make the double assumption of the meaning of the word and the existence of the thing. The reason is that these several objects are not equally obvious to us. Recognition of a truth may in some cases contain as factors both previous knowledge and also knowledge acquired simultaneously with that recognition-knowledge, this latter, of the particulars actually falling under the universal and therein already virtually known. For example, the student knew beforehand that the angles of every triangle 20are equal to two right angles; but it was only at the actual moment at which he was being led on to recognize this as true in the instance before him that he came to know 'this figure inscribed in the semicircle' to be a triangle. For some things (viz. the singulars finally reached which are not predicable of anything else as subject) are only learnt in this way, i.e. there is here no recognition through a middle of a minor term as subject to a major. Before he was led on to recognition 25or before he actually drew a conclusion, we should perhaps say that in a manner he knew, in a manner not.
If he did not in an unqualified sense of the term know the existence of this triangle, how could he know without qualification that its angles were equal to two right angles? No: clearly he knows not without qualification but only in the sense that he knows universally. If this distinction is not drawn, we are faced with the dilemma in the Meno: 30either a man will learn nothing or what he already knows; for we cannot accept the solution which some people offer. A man is asked, 'Do you, or do you not, know that every pair is even?' He says he does know it. The questioner then produces a particular pair, of the existence, and so a fortiori of the evenness, of which he was unaware. The solution which some people offer is to assert that they do not know that every pair is even, but only that everything which they know to be a pair is even: yet what they know to be even is that of which they have demonstrated evenness, i.e.
71b
1 ἴσασι μὲν οὗπερ τὴν ἀπόδειξιν ἔχουσι καὶ οὗ ἔλαβον, ἔλαβον
δ' οὐχὶ παντὸς οὗ ἂν εἰδῶσιν ὅτι τρίγωνον ἢ ὅτι ἀριθμός,
ἀλλ' ἁπλῶς κατὰ παντὸς ἀριθμοῦ καὶ τριγώνου· οὐδεμία
γὰρ πρότασις λαμβάνεται τοιαύτη, ὅτι ὃν σὺ οἶδας ἀριθμὸν
5 ἢ ὃ σὺ οἶδας εὐθύγραμμον, ἀλλὰ κατὰ παντός. ἀλλ'
οὐδέν (οἶμαι) κωλύει, ὃ μανθάνει, ἔστιν ὡς ἐπίστασθαι, ἔστι
δ' ὡς ἀγνοεῖν· ἄτοπον γὰρ οὐκ εἰ οἶδέ πως ὃ μανθάνει, ἀλλ'
εἰ ὡδί, οἷον ᾗ μανθάνει καὶ ὥς.
1what they made the subject of their premiss, viz. not merely every triangle or number which they know to be such, but any and every number or triangle without reservation. For no premiss is ever couched in the form 'every number which you know to be such', or '5every rectilinear figure which you know to be such': the predicate is always construed as applicable to any and every instance of the thing. On the other hand, I imagine there is nothing to prevent a man in one sense knowing what he is learning, in another not knowing it. The strange thing would be, not if in some sense he knew what he was learning, but if he were to know it in that precise sense and manner in which he was learning it.
Book 1,Chapter 2 (71b9–72b4)
Ἐπίστασθαι δὲ οἰόμεθ' ἕκαστον ἁπλῶς, ἀλλὰ μὴ τὸν
10 σοφιστικὸν τρόπον τὸν κατὰ συμβεβηκός, ὅταν τήν τ' αἰτίαν
οἰώμεθα γινώσκειν δι' ἣν τὸ πρᾶγμά ἐστιν, ὅτι ἐκείνου αἰτία
ἐστί, καὶ μὴ ἐνδέχεσθαι τοῦτ' ἄλλως ἔχειν. δῆλον τοίνυν ὅτι
τοιοῦτόν τι τὸ ἐπίστασθαί ἐστι· καὶ γὰρ οἱ μὴ ἐπιστάμενοι καὶ
οἱ ἐπιστάμενοι οἱ μὲν οἴονται αὐτοὶ οὕτως ἔχειν, οἱ δ' ἐπιστάμενοι
15 καὶ ἔχουσιν, ὥστε οὗ ἁπλῶς ἔστιν ἐπιστήμη, τοῦτ' ἀδύνατον
ἄλλως ἔχειν. Εἰ μὲν οὖν καὶ ἕτερος ἔστι τοῦ ἐπίστασθαι τρόπος,
ὕστερον ἐροῦμεν, φαμὲν δὲ καὶ δι' ἀποδείξεως εἰδέναι. ἀπόδειξιν
δὲ λέγω συλλογισμὸν ἐπιστημονικόν· ἐπιστημονικὸν δὲ
λέγω καθ' ὃν τῷ ἔχειν αὐτὸν ἐπιστάμεθα. εἰ τοίνυν ἐστὶ τὸ ἐπίστασθαι
20 οἷον ἔθεμεν, ἀνάγκη καὶ τὴν ἀποδεικτικὴν ἐπιστήμην ἐξ
ἀληθῶν τ' εἶναι καὶ πρώτων καὶ ἀμέσων καὶ γνωριμωτέρων
καὶ προτέρων καὶ αἰτίων τοῦ συμπεράσματος· οὕτω γὰρ ἔσονται
καὶ αἱ ἀρχαὶ οἰκεῖαι τοῦ δεικνυμένου. συλλογισμὸς μὲν
γὰρ ἔσται καὶ ἄνευ τούτων, ἀπόδειξις δ' οὐκ ἔσται· οὐ γὰρ
25 ποιήσει ἐπιστήμην. ἀληθῆ μὲν οὖν δεῖ εἶναι, ὅτι οὐκ ἔστι τὸ μὴ
ὂν ἐπίστασθαι, οἷον ὅτι ἡ διάμετρος σύμμετρος. ἐκ πρώτων
δ' ἀναποδείκτων, ὅτι οὐκ ἐπιστήσεται μὴ ἔχων ἀπόδειξιν αὐτῶν·
τὸ γὰρ ἐπίστασθαι ὧν ἀπόδειξις ἔστι μὴ κατὰ συμβεβηκός,
τὸ ἔχειν ἀπόδειξίν ἐστιν. αἴτιά τε καὶ γνωριμώτερα
30 δεῖ εἶναι καὶ πρότερα, αἴτια μὲν ὅτι τότε ἐπιστάμεθα ὅταν
τὴν αἰτίαν εἰδῶμεν, καὶ πρότερα, εἴπερ αἴτια, καὶ προγινωσκόμενα
οὐ μόνον τὸν ἕτερον τρόπον τῷ ξυνιέναι, ἀλλὰ καὶ
τῷ εἰδέναι ὅτι ἔστιν. πρότερα δ' ἐστὶ καὶ γνωριμώτερα διχῶς·
οὐ γὰρ ταὐτὸν πρότερον τῇ φύσει καὶ πρὸς ἡμᾶς πρότερον,
9We suppose ourselves to possess unqualified scientific knowledge of a thing, as opposed to 10knowing it in the accidental way in which the sophist knows, when we think that we know the cause on which the fact depends, as the cause of that fact and of no other, and, further, that the fact could not be other than it is. Now that scientific knowing is something of this sort is evident-witness both those who falsely claim it and those who actually possess it, since the former merely imagine themselves to be, 15while the latter are also actually, in the condition described. Consequently the proper object of unqualified scientific knowledge is something which cannot be other than it is.
There may be another manner of knowing as well-that will be discussed later. What I now assert is that at all events we do know by demonstration. By demonstration I mean a syllogism productive of scientific knowledge, a syllogism, that is, the grasp of which is eo ipso such knowledge. Assuming then that my thesis as to the nature of scientific knowing is 20correct, the premisses of demonstrated knowledge must be true, primary, immediate, better known than and prior to the conclusion, which is further related to them as effect to cause. Unless these conditions are satisfied, the basic truths will not be 'appropriate' to the conclusion. Syllogism there may indeed be without these conditions, but such syllogism, not being 25productive of scientific knowledge, will not be demonstration. The premisses must be true: for that which is non-existent cannot be known-we cannot know, e.g. that the diagonal of a square is commensurate with its side. The premisses must be primary and indemonstrable; otherwise they will require demonstration in order to be known, since to have knowledge, if it be not accidental knowledge, of things which are demonstrable, means precisely to have a demonstration of them. The premisses must be the causes of the conclusion, better known than it, 30and prior to it; its causes, since we possess scientific knowledge of a thing only when we know its cause; prior, in order to be causes; antecedently known, this antecedent knowledge being not our mere understanding of the meaning, but knowledge of the fact as well.
There may be another manner of knowing as well-that will be discussed later. What I now assert is that at all events we do know by demonstration. By demonstration I mean a syllogism productive of scientific knowledge, a syllogism, that is, the grasp of which is eo ipso such knowledge. Assuming then that my thesis as to the nature of scientific knowing is 20correct, the premisses of demonstrated knowledge must be true, primary, immediate, better known than and prior to the conclusion, which is further related to them as effect to cause. Unless these conditions are satisfied, the basic truths will not be 'appropriate' to the conclusion. Syllogism there may indeed be without these conditions, but such syllogism, not being 25productive of scientific knowledge, will not be demonstration. The premisses must be true: for that which is non-existent cannot be known-we cannot know, e.g. that the diagonal of a square is commensurate with its side. The premisses must be primary and indemonstrable; otherwise they will require demonstration in order to be known, since to have knowledge, if it be not accidental knowledge, of things which are demonstrable, means precisely to have a demonstration of them. The premisses must be the causes of the conclusion, better known than it, 30and prior to it; its causes, since we possess scientific knowledge of a thing only when we know its cause; prior, in order to be causes; antecedently known, this antecedent knowledge being not our mere understanding of the meaning, but knowledge of the fact as well.
72a
1 οὐδὲ γνωριμώτερον καὶ ἡμῖν γνωριμώτερον. λέγω δὲ πρὸς
ἡμᾶς μὲν πρότερα καὶ γνωριμώτερα τὰ ἐγγύτερον τῆς αἰσθήσεως,
ἁπλῶς δὲ πρότερα καὶ γνωριμώτερα τὰ πορρώτερον.
ἔστι δὲ πορρωτάτω μὲν τὰ καθόλου μάλιστα, ἐγγυτάτω
5 δὲ τὰ καθ' ἕκαστα· καὶ ἀντίκειται ταῦτ' ἀλλήλοις. ἐκ πρώτων
δ' ἐστὶ τὸ ἐξ ἀρχῶν οἰκείων· ταὐτὸ γὰρ λέγω πρῶτον
καὶ ἀρχήν. ἀρχὴ δ' ἐστὶν ἀποδείξεως πρότασις ἄμεσος,
ἄμεσος δὲ ἧς μὴ ἔστιν ἄλλη προτέρα. πρότασις δ' ἐστὶν ἀποφάνσεως
τὸ ἕτερον μόριον, ἓν καθ' ἑνός, διαλεκτικὴ μὲν ἡ
10 ὁμοίως λαμβάνουσα ὁποτερονοῦν, ἀποδεικτικὴ δὲ ἡ ὡρισμένως
θάτερον, ὅτι ἀληθές. ἀπόφανσις δὲ ἀντιφάσεως ὁποτερονοῦν
μόριον, ἀντίφασις δὲ ἀντίθεσις ἧς οὐκ ἔστι μεταξὺ
καθ' αὑτήν, μόριον δ' ἀντιφάσεως τὸ μὲν τὶ κατὰ τινὸς κατάφασις,
τὸ δὲ τὶ ἀπὸ τινὸς ἀπόφασις. Ἀμέσου δ' ἀρχῆς
15 συλλογιστικῆς θέσιν μὲν λέγω ἣν μὴ ἔστι δεῖξαι, μηδ'
ἀνάγκη ἔχειν τὸν μαθησόμενόν τι· ἣν δ' ἀνάγκη ἔχειν τὸν
ὁτιοῦν μαθησόμενον, ἀξίωμα· ἔστι γὰρ ἔνια τοιαῦτα· τοῦτο
γὰρ μάλιστ' ἐπὶ τοῖς τοιούτοις εἰώθαμεν ὄνομα λέγειν. θέσεως
δ' ἡ μὲν ὁποτερονοῦν τῶν μορίων τῆς ἀντιφάσεως λαμβάνουσα,
20 οἷον λέγω τὸ εἶναί τι ἢ τὸ μὴ εἶναί τι, ὑπόθεσις, ἡ
δ' ἄνευ τούτου ὁρισμός. ὁ γὰρ ὁρισμὸς θέσις μέν ἐστι· τίθεται
γὰρ ὁ ἀριθμητικὸς μονάδα τὸ ἀδιαίρετον εἶναι κατὰ τὸ
ποσόν· ὑπόθεσις δ' οὐκ ἔστι· τὸ γὰρ τί ἐστι μονὰς καὶ τὸ εἶναι
μονάδα οὐ ταὐτόν.
25 Ἐπεὶ δὲ δεῖ πιστεύειν τε καὶ εἰδέναι τὸ πρᾶγμα τῷ
τοιοῦτον ἔχειν συλλογισμὸν ὃν καλοῦμεν ἀπόδειξιν, ἔστι δ'
οὗτος τῷ ταδὶ εἶναι ἐξ ὧν ὁ συλλογισμός, ἀνάγκη μὴ μόνον
προγινώσκειν τὰ πρῶτα, ἢ πάντα ἢ ἔνια, ἀλλὰ καὶ μᾶλλον·
αἰεὶ γὰρ δι' ὃ ὑπάρχει ἕκαστον, ἐκείνῳ μᾶλλον ὑπάρχει,
30 οἷον δι' ὃ φιλοῦμεν, ἐκεῖνο φίλον μᾶλλον. ὥστ' εἴπερ
ἴσμεν διὰ τὰ πρῶτα καὶ πιστεύομεν, κἀκεῖνα ἴσμεν τε καὶ
πιστεύομεν μᾶλλον, ὅτι δι' ἐκεῖνα καὶ τὰ ὕστερα. οὐχ οἷόν
τε δὲ πιστεύειν μᾶλλον ὧν οἶδεν ἃ μὴ τυγχάνει μήτε εἰδὼς
μήτε βέλτιον διακείμενος ἢ εἰ ἐτύγχανεν εἰδώς. συμβήσεται
35 δὲ τοῦτο, εἰ μή τις προγνώσεται τῶν δι' ἀπόδειξιν πιστευόντων·
μᾶλλον γὰρ ἀνάγκη πιστεύειν ταῖς ἀρχαῖς ἢ πάσαις
ἢ τισὶ τοῦ συμπεράσματος. τὸν δὲ μέλλοντα ἕξειν τὴν ἐπιστήμην
τὴν δι' ἀποδείξεως οὐ μόνον δεῖ τὰς ἀρχὰς μᾶλλον
γνωρίζειν καὶ μᾶλλον αὐταῖς πιστεύειν ἢ τῷ δεικνυμένῳ,
1Now 'prior' and 'better known' are ambiguous terms, for there is a difference between what is prior and better known in the order of being and what is prior and better known to man. I mean that objects nearer to sense are prior and better known to man; objects without qualification prior and better known are those further from sense. Now the most universal causes are furthest from sense and 5particular causes are nearest to sense, and they are thus exactly opposed to one another. In saying that the premisses of demonstrated knowledge must be primary, I mean that they must be the 'appropriate' basic truths, for I identify primary premiss and basic truth. A 'basic truth' in a demonstration is an immediate proposition. An immediate proposition is one which has no other proposition prior to it. A proposition is either part of an enunciation, i.e. it predicates a single attribute of a single subject. If a proposition is dialectical, it 10assumes either part indifferently; if it is demonstrative, it lays down one part to the definite exclusion of the other because that part is true. The term 'enunciation' denotes either part of a contradiction indifferently. A contradiction is an opposition which of its own nature excludes a middle. The part of a contradiction which conjoins a predicate with a subject is an affirmation; the part disjoining them is a negation. I call an immediate basic truth 15of syllogism a 'thesis' when, though it is not susceptible of proof by the teacher, yet ignorance of it does not constitute a total bar to progress on the part of the pupil: one which the pupil must know if he is to learn anything whatever is an axiom. I call it an axiom because there are such truths and we give them the name of axioms par excellence. If a thesis assumes one part or the other of an enunciation, 20i.e. asserts either the existence or the non-existence of a subject, it is a hypothesis; if it does not so assert, it is a definition. Definition is a 'thesis' or a 'laying something down', since the arithmetician lays it down that to be a unit is to be quantitatively indivisible; but it is not a hypothesis, for to define what a unit is is not the same as to affirm its existence.
25Now since the required ground of our knowledge-i.e. of our conviction-of a fact is the possession of such a syllogism as we call demonstration, and the ground of the syllogism is the facts constituting its premisses, we must not only know the primary premisses-some if not all of them-beforehand, but know them better than the conclusion: for the cause of an attribute's inherence in a subject always itself inheres in the subject more firmly than that attribute; 30e.g. the cause of our loving anything is dearer to us than the object of our love. So since the primary premisses are the cause of our knowledge-i.e. of our conviction-it follows that we know them better-that is, are more convinced of them-than their consequences, precisely because of our knowledge of the latter is the effect of our knowledge of the premisses. Now a man cannot believe in anything more than in the things he knows, unless he has either actual knowledge of it or something better than actual knowledge. 35But we are faced with this paradox if a student whose belief rests on demonstration has not prior knowledge; a man must believe in some, if not in all, of the basic truths more than in the conclusion.
25Now since the required ground of our knowledge-i.e. of our conviction-of a fact is the possession of such a syllogism as we call demonstration, and the ground of the syllogism is the facts constituting its premisses, we must not only know the primary premisses-some if not all of them-beforehand, but know them better than the conclusion: for the cause of an attribute's inherence in a subject always itself inheres in the subject more firmly than that attribute; 30e.g. the cause of our loving anything is dearer to us than the object of our love. So since the primary premisses are the cause of our knowledge-i.e. of our conviction-it follows that we know them better-that is, are more convinced of them-than their consequences, precisely because of our knowledge of the latter is the effect of our knowledge of the premisses. Now a man cannot believe in anything more than in the things he knows, unless he has either actual knowledge of it or something better than actual knowledge. 35But we are faced with this paradox if a student whose belief rests on demonstration has not prior knowledge; a man must believe in some, if not in all, of the basic truths more than in the conclusion.
72b
1 ἀλλὰ μηδ' ἄλλο αὐτῷ πιστότερον εἶναι μηδὲ γνωριμώτερον
τῶν ἀντικειμένων ταῖς ἀρχαῖς ἐξ ὧν ἔσται συλλογισμὸς ὁ
τῆς ἐναντίας ἀπάτης, εἴπερ δεῖ τὸν ἐπιστάμενον ἁπλῶς ἀμετάπειστον
εἶναι.
1Moreover, if a man sets out to acquire the scientific knowledge that comes through demonstration, he must not only have a better knowledge of the basic truths and a firmer conviction of them than of the connexion which is being demonstrated: more than this, nothing must be more certain or better known to him than these basic truths in their character as contradicting the fundamental premisses which lead to the opposed and erroneous conclusion. For indeed the conviction of pure science must be unshakable.
Book 1,Chapter 3 (72b5–73a20)
5 Ἐνίοις μὲν οὖν διὰ τὸ δεῖν τὰ πρῶτα ἐπίστασθαι οὐ δοκεῖ
ἐπιστήμη εἶναι, τοῖς δ' εἶναι μέν, πάντων μέντοι ἀπόδειξις
εἶναι· ὧν οὐδέτερον οὔτ' ἀληθὲς οὔτ' ἀναγκαῖον. οἱ μὲν γὰρ
ὑποθέμενοι μὴ εἶναι ὅλως ἐπίστασθαι, οὗτοι εἰς ἄπειρον ἀξιοῦσιν
ἀνάγεσθαι ὡς οὐκ ἂν ἐπισταμένους τὰ ὕστερα διὰ τὰ
10 πρότερα, ὧν μὴ ἔστι πρῶτα, ὀρθῶς λέγοντες· ἀδύνατον γὰρ
τὰ ἄπειρα διελθεῖν. εἴ τε ἵσταται καὶ εἰσὶν ἀρχαί, ταύτας
ἀγνώστους εἶναι ἀποδείξεώς γε μὴ οὔσης αὐτῶν, ὅπερ φασὶν
εἶναι τὸ ἐπίστασθαι μόνον· εἰ δὲ μὴ ἔστι τὰ πρῶτα εἰδέναι,
οὐδὲ τὰ ἐκ τούτων εἶναι ἐπίστασθαι ἁπλῶς οὐδὲ κυρίως, ἀλλ'
15 ἐξ ὑποθέσεως, εἰ ἐκεῖνα ἔστιν. οἱ δὲ περὶ μὲν τοῦ ἐπίστασθαι
ὁμολογοῦσι· δι' ἀποδείξεως γὰρ εἶναι μόνον· ἀλλὰ πάντων
εἶναι ἀπόδειξιν οὐδὲν κωλύειν· ἐνδέχεσθαι γὰρ κύκλῳ γίνεσθαι
τὴν ἀπόδειξιν καὶ ἐξ ἀλλήλων. Ἡμεῖς δέ φαμεν οὔτε
πᾶσαν ἐπιστήμην ἀποδεικτικὴν εἶναι, ἀλλὰ τὴν τῶν ἀμέσων
20 ἀναπόδεικτον (καὶ τοῦθ' ὅτι ἀναγκαῖον, φανερόν· εἰ γὰρ
ἀνάγκη μὲν ἐπίστασθαι τὰ πρότερα καὶ ἐξ ὧν ἡ ἀπόδειξις,
ἵσταται δέ ποτε τὰ ἄμεσα, ταῦτ' ἀναπόδεικτα ἀνάγκη εἶναι)—
ταῦτά τ' οὖν οὕτω λέγομεν, καὶ οὐ μόνον ἐπιστήμην ἀλλὰ
καὶ ἀρχὴν ἐπιστήμης εἶναί τινά φαμεν, ᾗ τοὺς ὅρους γνωρίζομεν.
25 κύκλῳ τε ὅτι ἀδύνατον ἀποδείκνυσθαι ἁπλῶς, δῆλον,
εἴπερ ἐκ προτέρων δεῖ τὴν ἀπόδειξιν εἶναι καὶ γνωριμωτέρων·
ἀδύνατον γάρ ἐστι τὰ αὐτὰ τῶν αὐτῶν ἅμα πρότερα
καὶ ὕστερα εἶναι, εἰ μὴ τὸν ἕτερον τρόπον, οἷον τὰ μὲν πρὸς
ἡμᾶς τὰ δ' ἁπλῶς, ὅνπερ τρόπον ἡ ἐπαγωγὴ ποιεῖ γνώριμον.
30 εἰ δ' οὕτως, οὐκ ἂν εἴη τὸ ἁπλῶς εἰδέναι καλῶς ὡρισμένον,
ἀλλὰ διττόν· ἢ οὐχ ἁπλῶς ἡ ἑτέρα ἀπόδειξις, γινομένη
γ' ἐκ τῶν ἡμῖν γνωριμωτέρων. συμβαίνει δὲ τοῖς λέγουσι
κύκλῳ τὴν ἀπόδειξιν εἶναι οὐ μόνον τὸ νῦν εἰρημένον, ἀλλ'
οὐδὲν ἄλλο λέγειν ἢ ὅτι τοῦτ' ἔστιν εἰ τοῦτ' ἔστιν· οὕτω δὲ πάντα
35 ῥᾴδιον δεῖξαι. δῆλον δ' ὅτι τοῦτο συμβαίνει τριῶν ὅρων τεθέντων.
τὸ μὲν γὰρ διὰ πολλῶν ἢ δι' ὀλίγων ἀνακάμπτειν
φάναι οὐδὲν διαφέρει, δι' ὀλίγων δ' ἢ δυοῖν. ὅταν γὰρ τοῦ
Α ὄντος ἐξ ἀνάγκης ᾖ τὸ Β, τούτου δὲ τὸ Γ, τοῦ Α ὄντος
ἔσται τὸ Γ. εἰ δὴ τοῦ Α ὄντος ἀνάγκη τὸ Β εἶναι, τούτου δ'
5Some hold that, owing to the necessity of knowing the primary premisses, there is no scientific knowledge. Others think there is, but that all truths are demonstrable. Neither doctrine is either true or a necessary deduction from the premisses. The first school, assuming that there is no way of knowing other than by demonstration, maintain that an infinite regress is involved, on the ground that 10if behind the prior stands no primary, we could not know the posterior through the prior (wherein they are right, for one cannot traverse an infinite series): if on the other hand-they say-the series terminates and there are primary premisses, yet these are unknowable because incapable of demonstration, which according to them is the only form of knowledge. And since thus one cannot know the primary premisses, knowledge of the conclusions which follow from them is not pure scientific knowledge nor properly knowing at all, 15but rests on the mere supposition that the premisses are true. The other party agree with them as regards knowing, holding that it is only possible by demonstration, but they see no difficulty in holding that all truths are demonstrated, on the ground that demonstration may be circular and reciprocal.
Our own doctrine is that not all knowledge is demonstrative: on the contrary, knowledge of the immediate premisses is independent of demonstration. 20(The necessity of this is obvious; for since we must know the prior premisses from which the demonstration is drawn, and since the regress must end in immediate truths, those truths must be indemonstrable.) Such, then, is our doctrine, and in addition we maintain that besides scientific knowledge there is its originative source which enables us to recognize the definitions.
Now demonstration must be based on premisses prior to and better known than the conclusion; and the same things cannot simultaneously be both prior and posterior to one another: 25so circular demonstration is clearly not possible in the unqualified sense of 'demonstration', but only possible if 'demonstration' be extended to include that other method of argument which rests on a distinction between truths prior to us and truths without qualification prior, i.e. the method by which induction produces knowledge. 30But if we accept this extension of its meaning, our definition of unqualified knowledge will prove faulty; for there seem to be two kinds of it. Perhaps, however, the second form of demonstration, that which proceeds from truths better known to us, is not demonstration in the unqualified sense of the term.
The advocates of circular demonstration are not only faced with the difficulty we have just stated: in addition their theory reduces to the mere statement that if a thing exists, then it does exist-35an easy way of proving anything. That this is so can be clearly shown by taking three terms, for to constitute the circle it makes no difference whether many terms or few or even only two are taken.
Our own doctrine is that not all knowledge is demonstrative: on the contrary, knowledge of the immediate premisses is independent of demonstration. 20(The necessity of this is obvious; for since we must know the prior premisses from which the demonstration is drawn, and since the regress must end in immediate truths, those truths must be indemonstrable.) Such, then, is our doctrine, and in addition we maintain that besides scientific knowledge there is its originative source which enables us to recognize the definitions.
Now demonstration must be based on premisses prior to and better known than the conclusion; and the same things cannot simultaneously be both prior and posterior to one another: 25so circular demonstration is clearly not possible in the unqualified sense of 'demonstration', but only possible if 'demonstration' be extended to include that other method of argument which rests on a distinction between truths prior to us and truths without qualification prior, i.e. the method by which induction produces knowledge. 30But if we accept this extension of its meaning, our definition of unqualified knowledge will prove faulty; for there seem to be two kinds of it. Perhaps, however, the second form of demonstration, that which proceeds from truths better known to us, is not demonstration in the unqualified sense of the term.
The advocates of circular demonstration are not only faced with the difficulty we have just stated: in addition their theory reduces to the mere statement that if a thing exists, then it does exist-35an easy way of proving anything. That this is so can be clearly shown by taking three terms, for to constitute the circle it makes no difference whether many terms or few or even only two are taken.
73a
1 ὄντος τὸ Α (τοῦτο γὰρ ἦν τὸ κύκλῳ), κείσθω τὸ Α ἐφ' οὗ
τὸ Γ. τὸ οὖν τοῦ Β ὄντος τὸ Α εἶναι λέγειν ἐστὶ τὸ Γ εἶναι λέγειν,
τοῦτο δ' ὅτι τοῦ Α ὄντος τὸ Γ ἔστι· τὸ δὲ Γ τῷ Α τὸ
αὐτό. ὥστε συμβαίνει λέγειν τοὺς κύκλῳ φάσκοντας εἶναι
5 τὴν ἀπόδειξιν οὐδὲν ἕτερον πλὴν ὅτι τοῦ Α ὄντος τὸ Α ἔστιν.
οὕτω δὲ πάντα δεῖξαι ῥᾴδιον. Οὐ μὴν ἀλλ' οὐδὲ τοῦτο δυνατόν,
πλὴν ἐπὶ τούτων ὅσα ἀλλήλοις ἕπεται, ὥσπερ τὰ ἴδια. ἑνὸς
μὲν οὖν κειμένου δέδεικται ὅτι οὐδέποτ' ἀνάγκη τι εἶναι ἕτερον
(λέγω δ' ἑνός, ὅτι οὔτε ὅρου ἑνὸς οὔτε θέσεως μιᾶς τεθείσης),
10 ἐκ δύο δὲ θέσεων πρώτων καὶ ἐλαχίστων ἐνδέχεται,
εἴπερ καὶ συλλογίσασθαι. ἐὰν μὲν οὖν τό τε Α τῷ Β καὶ τῷ
Γ ἕπηται, καὶ ταῦτ' ἀλλήλοις καὶ τῷ Α, οὕτω μὲν ἐνδέχεται
ἐξ ἀλλήλων δεικνύναι πάντα τὰ αἰτηθέντα ἐν τῷ
πρώτῳ σχήματι, ὡς δέδεικται ἐν τοῖς περὶ συλλογισμοῦ.
15 δέδεικται δὲ καὶ ὅτι ἐν τοῖς ἄλλοις σχήμασιν ἢ οὐ γίνεται
συλλογισμὸς ἢ οὐ περὶ τῶν ληφθέντων. τὰ δὲ μὴ ἀντικατηγορούμενα
οὐδαμῶς ἔστι δεῖξαι κύκλῳ, ὥστ' ἐπειδὴ ὀλίγα τοιαῦτα
ἐν ταῖς ἀποδείξεσι, φανερὸν ὅτι κενόν τε καὶ ἀδύνατον
τὸ λέγειν ἐξ ἀλλήλων εἶναι τὴν ἀπόδειξιν καὶ διὰ τοῦτο
20 πάντων ἐνδέχεσθαι εἶναι ἀπόδειξιν.
1Thus by direct proof, if A is, B must be; if B is, C must be; therefore if A is, C must be. Since then-by the circular proof-if A is, B must be, and if B is, A must be, A may be substituted for C above. Then 'if B is, A must be'='if B is, C must be', which above gave the conclusion 'if A is, C must be': but C and A have been identified. Consequently the upholders of circular demonstration 5are in the position of saying that if A is, A must be-a simple way of proving anything. Moreover, even such circular demonstration is impossible except in the case of attributes that imply one another, viz. 'peculiar' properties.
Now, it has been shown that the positing of one thing-be it one term or one premiss-never involves a necessary consequent: 10two premisses constitute the first and smallest foundation for drawing a conclusion at all and therefore a fortiori for the demonstrative syllogism of science. If, then, A is implied in B and C, and B and C are reciprocally implied in one another and in A, it is possible, as has been shown in my writings on the syllogism, to prove all the assumptions on which the original conclusion rested, by circular demonstration in the first figure. 15But it has also been shown that in the other figures either no conclusion is possible, or at least none which proves both the original premisses. Propositions the terms of which are not convertible cannot be circularly demonstrated at all, and since convertible terms occur rarely in actual demonstrations, it is clearly frivolous and impossible to say that demonstration is reciprocal and 20that therefore everything can be demonstrated.
Now, it has been shown that the positing of one thing-be it one term or one premiss-never involves a necessary consequent: 10two premisses constitute the first and smallest foundation for drawing a conclusion at all and therefore a fortiori for the demonstrative syllogism of science. If, then, A is implied in B and C, and B and C are reciprocally implied in one another and in A, it is possible, as has been shown in my writings on the syllogism, to prove all the assumptions on which the original conclusion rested, by circular demonstration in the first figure. 15But it has also been shown that in the other figures either no conclusion is possible, or at least none which proves both the original premisses. Propositions the terms of which are not convertible cannot be circularly demonstrated at all, and since convertible terms occur rarely in actual demonstrations, it is clearly frivolous and impossible to say that demonstration is reciprocal and 20that therefore everything can be demonstrated.
Book 1,Chapter 4 (73a21–74a3)
Ἐπεὶ δ' ἀδύνατον ἄλλως ἔχειν οὗ ἔστιν ἐπιστήμη ἁπλῶς,
ἀναγκαῖον ἂν εἴη τὸ ἐπιστητὸν τὸ κατὰ τὴν ἀποδεικτικὴν ἐπιστήμην·
ἀποδεικτικὴ δ' ἐστὶν ἣν ἔχομεν τῷ ἔχειν ἀπόδειξιν.
ἐξ ἀναγκαίων ἄρα συλλογισμός ἐστιν ἡ ἀπόδειξις. ληπτέον
25 ἄρα ἐκ τίνων καὶ ποίων αἱ ἀποδείξεις εἰσίν. πρῶτον δὲ διορίσωμεν
τί λέγομεν τὸ κατὰ παντὸς καὶ τί τὸ καθ' αὑτὸ καὶ
τί τὸ καθόλου.
Κατὰ παντὸς μὲν οὖν τοῦτο λέγω ὃ ἂν ᾖ μὴ ἐπὶ τινὸς
μὲν τινὸς δὲ μή, μηδὲ ποτὲ μὲν ποτὲ δὲ μή, οἷον εἰ κατὰ
30 παντὸς ἀνθρώπου ζῷον, εἰ ἀληθὲς τόνδ' εἰπεῖν ἄνθρωπον,
ἀληθὲς καὶ ζῷον, καὶ εἰ νῦν θάτερον, καὶ θάτερον, καὶ εἰ ἐν
πάσῃ γραμμῇ στιγμή, ὡσαύτως. σημεῖον δέ· καὶ γὰρ τὰς
ἐνστάσεις οὕτω φέρομεν ὡς κατὰ παντὸς ἐρωτώμενοι, ἢ εἰ ἐπί
τινι μή, ἢ εἴ ποτε μή. Καθ' αὑτὰ δ' ὅσα ὑπάρχει τε ἐν
35 τῷ τί ἐστιν, οἷον τριγώνῳ γραμμὴ καὶ γραμμῇ στιγμή (ἡ
γὰρ οὐσία αὐτῶν ἐκ τούτων ἐστί, καὶ ἐν τῷ λόγῳ τῷ λέγοντι
τί ἐστιν ἐνυπάρχει), καὶ ὅσοις τῶν ὑπαρχόντων αὐτοῖς αὐτὰ
ἐν τῷ λόγῳ ἐνυπάρχουσι τῷ τί ἐστι δηλοῦντι, οἷον τὸ εὐθὺ
ὑπάρχει γραμμῇ καὶ τὸ περιφερές, καὶ τὸ περιττὸν καὶ
40 ἄρτιον ἀριθμῷ, καὶ τὸ πρῶτον καὶ σύνθετον, καὶ ἰσόπλευρον
21Since the object of pure scientific knowledge cannot be other than it is, the truth obtained by demonstrative knowledge will be necessary. And since demonstrative knowledge is only present when we have a demonstration, it follows that demonstration is an inference from necessary premisses. 25So we must consider what are the premisses of demonstration-i.e. what is their character: and as a preliminary, let us define what we mean by an attribute 'true in every instance of its subject', an 'essential' attribute, and a 'commensurate and universal' attribute. I call 'true in every instance' what is truly predicable of all instances-not of one to the exclusion of others-and at all times, not at this or that time only; e.g. if animal 30is truly predicable of every instance of man, then if it be true to say 'this is a man', 'this is an animal' is also true, and if the one be true now the other is true now. A corresponding account holds if point is in every instance predicable as contained in line. There is evidence for this in the fact that the objection we raise against a proposition put to us as true in every instance is either an instance in which, or an occasion on which, it is not true. Essential attributes are (1) such as belong to their subject 35as elements in its essential nature (e.g. line thus belongs to triangle, point to line; for the very being or 'substance' of triangle and line is composed of these elements, which are contained in the formulae defining triangle and line): (2) such that, while they belong to certain subjects, the subjects to which they belong are contained in the attribute's own defining formula. Thus straight and curved belong to line, odd and 40even, prime and compound, square and oblong, to number; and also the formula defining any one of these attributes contains its subject-e.g. line or number as the case may be.
73b
1 καὶ ἑτερόμηκες· καὶ πᾶσι τούτοις ἐνυπάρχουσιν ἐν τῷ
λόγῳ τῷ τί ἐστι λέγοντι ἔνθα μὲν γραμμὴ ἔνθα δ' ἀριθμός.
ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων τὰ τοιαῦθ' ἑκάστοις καθ'
αὑτὰ λέγω, ὅσα δὲ μηδετέρως ὑπάρχει, συμβεβηκότα,
5 οἷον τὸ μουσικὸν ἢ λευκὸν τῷ ζῴῳ. ἔτι ὃ μὴ καθ' ὑποκειμένου
λέγεται ἄλλου τινός, οἷον τὸ βαδίζον ἕτερόν τι ὂν βαδίζον
ἐστὶ καὶ τὸ λευκὸν <λευκόν>, ἡ δ' οὐσία, καὶ ὅσα τόδε τι
σημαίνει, οὐχ ἕτερόν τι ὄντα ἐστὶν ὅπερ ἐστίν. τὰ μὲν δὴ μὴ καθ'
ὑποκειμένου καθ' αὑτὰ λέγω, τὰ δὲ καθ' ὑποκειμένου συμβεβηκότα.
10 ἔτι δ' ἄλλον τρόπον τὸ μὲν δι' αὑτὸ ὑπάρχον
ἑκάστῳ καθ' αὑτό, τὸ δὲ μὴ δι' αὑτὸ συμβεβηκός, οἷον εἰ
βαδίζοντος ἤστραψε, συμβεβηκός· οὐ γὰρ διὰ τὸ βαδίζειν
ἤστραψεν, ἀλλὰ συνέβη, φαμέν, τοῦτο. εἰ δὲ δι' αὑτό,
καθ' αὑτό, οἷον εἴ τι σφαττόμενον ἀπέθανε, καὶ κατὰ τὴν
15 σφαγήν, ὅτι διὰ τὸ σφάττεσθαι, ἀλλ' οὐ συνέβη σφαττόμενον
ἀποθανεῖν. τὰ ἄρα λεγόμενα ἐπὶ τῶν ἁπλῶς ἐπιστητῶν
καθ' αὑτὰ οὕτως ὡς ἐνυπάρχειν τοῖς κατηγορουμένοις
ἢ ἐνυπάρχεσθαι δι' αὑτά τέ ἐστι καὶ ἐξ ἀνάγκης. οὐ γὰρ
ἐνδέχεται μὴ ὑπάρχειν ἢ ἁπλῶς ἢ τὰ ἀντικείμενα, οἷον
20 γραμμῇ τὸ εὐθὺ ἢ τὸ καμπύλον καὶ ἀριθμῷ τὸ περιττὸν
ἢ τὸ ἄρτιον. ἔστι γὰρ τὸ ἐναντίον ἢ στέρησις ἢ ἀντίφασις ἐν τῷ
αὐτῷ γένει, οἷον ἄρτιον τὸ μὴ περιττὸν ἐν ἀριθμοῖς ᾗ ἕπεται.
ὥστ' εἰ ἀνάγκη φάναι ἢ ἀποφάναι, ἀνάγκη καὶ τὰ καθ'
αὑτὰ ὑπάρχειν.
25 Τὸ μὲν οὖν κατὰ παντὸς καὶ καθ' αὑτὸ διωρίσθω τὸν
τρόπον τοῦτον· καθόλου δὲ λέγω ὃ ἂν κατὰ παντός τε
ὑπάρχῃ καὶ καθ' αὑτὸ καὶ ᾗ αὐτό. φανερὸν ἄρα ὅτι ὅσα
καθόλου, ἐξ ἀνάγκης ὑπάρχει τοῖς πράγμασιν. τὸ καθ'
αὑτὸ δὲ καὶ ᾗ αὐτὸ ταὐτόν, οἷον καθ' αὑτὴν τῇ γραμμῇ
30 ὑπάρχει στιγμὴ καὶ τὸ εὐθύ (καὶ γὰρ ᾗ γραμμή), καὶ τῷ
τριγώνῳ ᾗ τρίγωνον δύο ὀρθαί (καὶ γὰρ καθ' αὑτὸ τὸ τρίγωνον
δύο ὀρθαῖς ἴσον). τὸ καθόλου δὲ ὑπάρχει τότε, ὅταν
ἐπὶ τοῦ τυχόντος καὶ πρώτου δεικνύηται. οἷον τὸ δύο ὀρθὰς
ἔχειν οὔτε τῷ σχήματί ἐστι καθόλου (καίτοι ἔστι δεῖξαι
35 κατὰ σχήματος ὅτι δύο ὀρθὰς ἔχει, ἀλλ' οὐ τοῦ τυχόντος
σχήματος, οὐδὲ χρῆται τῷ τυχόντι σχήματι δεικνύς· τὸ
γὰρ τετράγωνον σχῆμα μέν, οὐκ ἔχει δὲ δύο ὀρθαῖς ἴσας)—
τὸ δ' ἰσοσκελὲς ἔχει μὲν τὸ τυχὸν δύο ὀρθαῖς ἴσας, ἀλλ'
οὐ πρῶτον, ἀλλὰ τὸ τρίγωνον πρότερον. ὃ τοίνυν τὸ τυχὸν
40 πρῶτον δείκνυται δύο ὀρθὰς ἔχον ἢ ὁτιοῦν ἄλλο, τούτῳ πρώτῳ
1Extending this classification to all other attributes, I distinguish those that answer the above description as belonging essentially to their respective subjects; whereas attributes related in neither of these two ways to their subjects I call accidents or 'coincidents'; e.g. 5musical or white is a 'coincident' of animal.
Further (a) that is essential which is not predicated of a subject other than itself: e.g. 'the walking [thing]' walks and is white in virtue of being something else besides; whereas substance, in the sense of whatever signifies a 'this somewhat', is not what it is in virtue of being something else besides. Things, then, not predicated of a subject I call essential; things predicated of a subject I call accidental or 'coincidental'.
10In another sense again (b) a thing consequentially connected with anything is essential; one not so connected is 'coincidental'. An example of the latter is 'While he was walking it lightened': the lightning was not due to his walking; it was, we should say, a coincidence. If, on the other hand, there is a consequential connexion, the predication is essential; e.g. if a beast dies when its throat is being cut, then its death is also essentially connected with 15the cutting, because the cutting was the cause of death, not death a 'coincident' of the cutting.
So far then as concerns the sphere of connexions scientifically known in the unqualified sense of that term, all attributes which (within that sphere) are essential either in the sense that their subjects are contained in them, or in the sense that they are contained in their subjects, are necessary as well as consequentially connected with their subjects. For it is impossible for them not to inhere in their subjects either simply or in the qualified sense that one or other of a pair of opposites must inhere in the subject; e.g. 20in line must be either straightness or curvature, in number either oddness or evenness. For within a single identical genus the contrary of a given attribute is either its privative or its contradictory; e.g. within number what is not odd is even, inasmuch as within this sphere even is a necessary consequent of not-odd. So, since any given predicate must be either affirmed or denied of any subject, essential attributes must inhere in their subjects of necessity.
25Thus, then, we have established the distinction between the attribute which is 'true in every instance' and the 'essential' attribute.
I term 'commensurately universal' an attribute which belongs to every instance of its subject, and to every instance essentially and as such; from which it clearly follows that all commensurate universals inhere necessarily in their subjects. The essential attribute, and the attribute that belongs to its subject as such, are identical. E.g. 30point and straight belong to line essentially, for they belong to line as such; and triangle as such has two right angles, for it is essentially equal to two right angles.
An attribute belongs commensurately and universally to a subject when it can be shown to belong to any random instance of that subject and when the subject is the first thing to which it can be shown to belong. Thus, e.g. (1) the equality of its angles to two right angles is not a commensurately universal attribute of figure. For though it is possible to show 35that a figure has its angles equal to two right angles, this attribute cannot be demonstrated of any figure selected at haphazard, nor in demonstrating does one take a figure at random-a square is a figure but its angles are not equal to two right angles. On the other hand, any isosceles triangle has its angles equal to two right angles, yet isosceles triangle is not the primary subject of this attribute but triangle is prior. So whatever 40can be shown to have its angles equal to two right angles, or to possess any other attribute, in any random instance of itself and primarily-that is the first subject to which the predicate in question belongs commensurately and universally, and the demonstration, in the essential sense, of any predicate is the proof of it as belonging to this first subject commensurately and universally: while the proof of it as belonging to the other subjects to which it attaches is demonstration only in a secondary and unessential sense.
Further (a) that is essential which is not predicated of a subject other than itself: e.g. 'the walking [thing]' walks and is white in virtue of being something else besides; whereas substance, in the sense of whatever signifies a 'this somewhat', is not what it is in virtue of being something else besides. Things, then, not predicated of a subject I call essential; things predicated of a subject I call accidental or 'coincidental'.
10In another sense again (b) a thing consequentially connected with anything is essential; one not so connected is 'coincidental'. An example of the latter is 'While he was walking it lightened': the lightning was not due to his walking; it was, we should say, a coincidence. If, on the other hand, there is a consequential connexion, the predication is essential; e.g. if a beast dies when its throat is being cut, then its death is also essentially connected with 15the cutting, because the cutting was the cause of death, not death a 'coincident' of the cutting.
So far then as concerns the sphere of connexions scientifically known in the unqualified sense of that term, all attributes which (within that sphere) are essential either in the sense that their subjects are contained in them, or in the sense that they are contained in their subjects, are necessary as well as consequentially connected with their subjects. For it is impossible for them not to inhere in their subjects either simply or in the qualified sense that one or other of a pair of opposites must inhere in the subject; e.g. 20in line must be either straightness or curvature, in number either oddness or evenness. For within a single identical genus the contrary of a given attribute is either its privative or its contradictory; e.g. within number what is not odd is even, inasmuch as within this sphere even is a necessary consequent of not-odd. So, since any given predicate must be either affirmed or denied of any subject, essential attributes must inhere in their subjects of necessity.
25Thus, then, we have established the distinction between the attribute which is 'true in every instance' and the 'essential' attribute.
I term 'commensurately universal' an attribute which belongs to every instance of its subject, and to every instance essentially and as such; from which it clearly follows that all commensurate universals inhere necessarily in their subjects. The essential attribute, and the attribute that belongs to its subject as such, are identical. E.g. 30point and straight belong to line essentially, for they belong to line as such; and triangle as such has two right angles, for it is essentially equal to two right angles.
An attribute belongs commensurately and universally to a subject when it can be shown to belong to any random instance of that subject and when the subject is the first thing to which it can be shown to belong. Thus, e.g. (1) the equality of its angles to two right angles is not a commensurately universal attribute of figure. For though it is possible to show 35that a figure has its angles equal to two right angles, this attribute cannot be demonstrated of any figure selected at haphazard, nor in demonstrating does one take a figure at random-a square is a figure but its angles are not equal to two right angles. On the other hand, any isosceles triangle has its angles equal to two right angles, yet isosceles triangle is not the primary subject of this attribute but triangle is prior. So whatever 40can be shown to have its angles equal to two right angles, or to possess any other attribute, in any random instance of itself and primarily-that is the first subject to which the predicate in question belongs commensurately and universally, and the demonstration, in the essential sense, of any predicate is the proof of it as belonging to this first subject commensurately and universally: while the proof of it as belonging to the other subjects to which it attaches is demonstration only in a secondary and unessential sense.
74a
1 ὑπάρχει καθόλου, καὶ ἡ ἀπόδειξις καθ' αὑτὸ τούτου καθόλου
ἐστί, τῶν δ' ἄλλων τρόπον τινὰ οὐ καθ' αὑτό, οὐδὲ τοῦ ἰσοσκελοῦς
οὐκ ἔστι καθόλου ἀλλ' ἐπὶ πλέον.
1Nor again (2) is equality to two right angles a commensurately universal attribute of isosceles; it is of wider application.
Book 1,Chapter 5 (74a4–74b4)
Δεῖ δὲ μὴ λανθάνειν ὅτι πολλάκις συμβαίνει διαμαρτάνειν
5 καὶ μὴ ὑπάρχειν τὸ δεικνύμενον πρῶτον καθόλου, ᾗ
δοκεῖ δείκνυσθαι καθόλου πρῶτον. ἀπατώμεθα δὲ ταύτην τὴν
ἀπάτην, ὅταν ἢ μηδὲν ᾖ λαβεῖν ἀνώτερον παρὰ τὸ καθ'
ἕκαστον [ἢ τὰ καθ' ἕκαστα], ἢ ᾖ μέν, ἀλλ' ἀνώνυμον ᾖ ἐπὶ
διαφόροις εἴδει πράγμασιν, ἢ τυγχάνῃ ὂν ὡς ἐν μέρει ὅλον
10 ἐφ' ᾧ δείκνυται· τοῖς γὰρ ἐν μέρει ὑπάρξει μὲν ἡ ἀπόδειξις,
καὶ ἔσται κατὰ παντός, ἀλλ' ὅμως οὐκ ἔσται τούτου πρώτου
καθόλου ἡ ἀπόδειξις. λέγω δὲ τούτου πρώτου, ᾗ τοῦτο, ἀπόδειξιν,
ὅταν ᾖ πρώτου καθόλου. εἰ οὖν τις δείξειεν ὅτι αἱ ὀρθαὶ
οὐ συμπίπτουσι, δόξειεν ἂν τούτου εἶναι ἡ ἀπόδειξις διὰ τὸ
15 ἐπὶ πασῶν εἶναι τῶν ὀρθῶν. οὐκ ἔστι δέ, εἴπερ μὴ ὅτι ὡδὶ
ἴσαι γίνεται τοῦτο, ἀλλ' ᾗ ὁπωσοῦν ἴσαι. καὶ εἰ τρίγωνον μὴ
ἦν ἄλλο ἢ ἰσοσκελές, ᾗ ἰσοσκελὲς ἂν ἐδόκει ὑπάρχειν. καὶ
τὸ ἀνάλογον ὅτι καὶ ἐναλλάξ, ᾗ ἀριθμοὶ καὶ ᾗ γραμμαὶ καὶ
ᾗ στερεὰ καὶ ᾗ χρόνοι, ὥσπερ ἐδείκνυτό ποτε χωρίς, ἐνδεχόμενόν
20 γε κατὰ πάντων μιᾷ ἀποδείξει δειχθῆναι· ἀλλὰ
διὰ τὸ μὴ εἶναι ὠνομασμένον τι ταῦτα πάντα ἓν, ἀριθμοί
μήκη χρόνοι στερεά, καὶ εἴδει διαφέρειν ἀλλήλων, χωρὶς
ἐλαμβάνετο. νῦν δὲ καθόλου δείκνυται· οὐ γὰρ ᾗ γραμμαὶ
ἢ ᾗ ἀριθμοὶ ὑπῆρχεν, ἀλλ' ᾗ τοδί, ὃ καθόλου ὑποτίθενται
25 ὑπάρχειν. διὰ τοῦτο οὐδ' ἄν τις δείξῃ καθ' ἕκαστον τὸ τρίγωνον
ἀποδείξει ἢ μιᾷ ἢ ἑτέρᾳ ὅτι δύο ὀρθὰς ἔχει ἕκαστον, τὸ
ἰσόπλευρον χωρὶς καὶ τὸ σκαληνὲς καὶ τὸ ἰσοσκελές, οὔπω
οἶδε τὸ τρίγωνον ὅτι δύο ὀρθαῖς, εἰ μὴ τὸν σοφιστικὸν τρόπον,
οὐδὲ καθ' ὅλου τριγώνου, οὐδ' εἰ μηδὲν ἔστι παρὰ ταῦτα
30 τρίγωνον ἕτερον. οὐ γὰρ ᾗ τρίγωνον οἶδεν, οὐδὲ πᾶν τρίγωνον,
ἀλλ' ἢ κατ' ἀριθμόν· κατ' εἶδος δ' οὐ πᾶν, καὶ εἰ μηδὲν
ἔστιν ὃ οὐκ οἶδεν. Πότ' οὖν οὐκ οἶδε καθόλου, καὶ πότ' οἶδεν
ἁπλῶς; δῆλον δὴ ὅτι εἰ ταὐτὸν ἦν τριγώνῳ εἶναι καὶ ἰσοπλεύρῳ
ἢ ἑκάστῳ ἢ πᾶσιν. εἰ δὲ μὴ ταὐτὸν ἀλλ' ἕτερον,
35 ὑπάρχει δ' ᾗ τρίγωνον, οὐκ οἶδεν. πότερον δ' ᾗ τρίγωνον ἢ
ᾗ ἰσοσκελὲς ὑπάρχει; καὶ πότε κατὰ τοῦθ' ὑπάρχει πρῶτον;
καὶ καθόλου τίνος ἡ ἀπόδειξις; δῆλον ὅτι ὅταν ἀφαιρουμένων
ὑπάρχῃ πρώτῳ. οἷον τῷ ἰσοσκελεῖ χαλκῷ τριγώνῳ
ὑπάρξουσι δύο ὀρθαί, ἀλλὰ καὶ τοῦ χαλκοῦν εἶναι ἀφαιρεθέντος
4We must not fail to observe that we often fall into error 5because our conclusion is not in fact primary and commensurately universal in the sense in which we think we prove it so. We make this mistake (1) when the subject is an individual or individuals above which there is no universal to be found: (2) when the subjects belong to different species and there is a higher universal, but it has no name: (3) when the subject which the demonstrator takes as a whole is really only a part of a larger whole; 10for then the demonstration will be true of the individual instances within the part and will hold in every instance of it, yet the demonstration will not be true of this subject primarily and commensurately and universally. When a demonstration is true of a subject primarily and commensurately and universally, that is to be taken to mean that it is true of a given subject primarily and as such. Case (3) may be thus exemplified. If a proof were given that perpendiculars to the same line are parallel, it might be supposed that lines thus perpendicular were the proper subject of the demonstration 15because being parallel is true of every instance of them. But it is not so, for the parallelism depends not on these angles being equal to one another because each is a right angle, but simply on their being equal to one another. An example of (1) would be as follows: if isosceles were the only triangle, it would be thought to have its angles equal to two right angles qua isosceles. An instance of (2) would be the law that proportionals alternate. Alternation used to be demonstrated separately of numbers, lines, solids, and durations, 20though it could have been proved of them all by a single demonstration. Because there was no single name to denote that in which numbers, lengths, durations, and solids are identical, and because they differed specifically from one another, this property was proved of each of them separately. To-day, however, the proof is commensurately universal, for they do not possess this attribute qua lines or qua numbers, but qua manifesting this generic character which they are postulated as possessing universally. 25Hence, even if one prove of each kind of triangle that its angles are equal to two right angles, whether by means of the same or different proofs; still, as long as one treats separately equilateral, scalene, and isosceles, one does not yet know, except sophistically, that triangle has its angles equal to two right angles, nor does one yet know that triangle has this property commensurately and universally, even if there is no other species of triangle but these. 30For one does not know that triangle as such has this property, nor even that 'all' triangles have it-unless 'all' means 'each taken singly': if 'all' means 'as a whole class', then, though there be none in which one does not recognize this property, one does not know it of 'all triangles'.
When, then, does our knowledge fail of commensurate universality, and when it is unqualified knowledge? If triangle be identical in essence with equilateral, i.e. with each or all equilaterals, then clearly we have unqualified knowledge: if on the other hand it be not, and 35the attribute belongs to equilateral qua triangle; then our knowledge fails of commensurate universality. 'But', it will be asked, 'does this attribute belong to the subject of which it has been demonstrated qua triangle or qua isosceles? What is the point at which the subject. to which it belongs is primary? (i.e. to what subject can it be demonstrated as belonging commensurately and universally?)' Clearly this point is the first term in which it is found to inhere as the elimination of inferior differentiae proceeds. Thus the angles of a brazen isosceles triangle are equal to two right angles: but eliminate brazen and isosceles and the attribute remains.
When, then, does our knowledge fail of commensurate universality, and when it is unqualified knowledge? If triangle be identical in essence with equilateral, i.e. with each or all equilaterals, then clearly we have unqualified knowledge: if on the other hand it be not, and 35the attribute belongs to equilateral qua triangle; then our knowledge fails of commensurate universality. 'But', it will be asked, 'does this attribute belong to the subject of which it has been demonstrated qua triangle or qua isosceles? What is the point at which the subject. to which it belongs is primary? (i.e. to what subject can it be demonstrated as belonging commensurately and universally?)' Clearly this point is the first term in which it is found to inhere as the elimination of inferior differentiae proceeds. Thus the angles of a brazen isosceles triangle are equal to two right angles: but eliminate brazen and isosceles and the attribute remains.
74b
1 καὶ τοῦ ἰσοσκελές. ἀλλ' οὐ τοῦ σχήματος ἢ πέρατος.
ἀλλ' οὐ πρώτων. τίνος οὖν πρώτου; εἰ δὴ τριγώνου, κατὰ τοῦτο
ὑπάρχει καὶ τοῖς ἄλλοις, καὶ τούτου καθόλου ἐστὶν ἡ ἀπόδειξις.
1'But'-you may say-'eliminate figure or limit, and the attribute vanishes.' True, but figure and limit are not the first differentiae whose elimination destroys the attribute. 'Then what is the first?' If it is triangle, it will be in virtue of triangle that the attribute belongs to all the other subjects of which it is predicable, and triangle is the subject to which it can be demonstrated as belonging commensurately and universally.
Book 1,Chapter 6 (74b5–75a37)
5 Εἰ οὖν ἐστιν ἡ ἀποδεικτικὴ ἐπιστήμη ἐξ ἀναγκαίων ἀρχῶν
(ὃ γὰρ ἐπίσταται, οὐ δυνατὸν ἄλλως ἔχειν), τὰ δὲ καθ'
αὑτὰ ὑπάρχοντα ἀναγκαῖα τοῖς πράγμασιν (τὰ μὲν γὰρ ἐν
τῷ τί ἐστιν ὑπάρχει· τοῖς δ' αὐτὰ ἐν τῷ τί ἐστιν ὑπάρχει
κατηγορουμένοις αὐτῶν, ὧν θάτερον τῶν ἀντικειμένων ἀνάγκη
10 ὑπάρχειν), φανερὸν ὅτι ἐκ τοιούτων τινῶν ἂν εἴη ὁ ἀποδεικτικὸς
συλλογισμός· ἅπαν γὰρ ἢ οὕτως ὑπάρχει ἢ κατὰ
συμβεβηκός, τὰ δὲ συμβεβηκότα οὐκ ἀναγκαῖα.
Ἢ δὴ οὕτω λεκτέον, ἢ ἀρχὴν θεμένοις ὅτι ἡ ἀπόδειξις
ἀναγκαίων ἐστί, καὶ εἰ ἀποδέδεικται, οὐχ οἷόν τ' ἄλλως
15 ἔχειν· ἐξ ἀναγκαίων ἄρα δεῖ εἶναι τὸν συλλογισμόν. ἐξ ἀληθῶν
μὲν γὰρ ἔστι καὶ μὴ ἀποδεικνύντα συλλογίσασθαι, ἐξ
ἀναγκαίων δ' οὐκ ἔστιν ἀλλ' ἢ ἀποδεικνύντα· τοῦτο γὰρ ἤδη
ἀποδείξεώς ἐστιν. σημεῖον δ' ὅτι ἡ ἀπόδειξις ἐξ ἀναγκαίων,
ὅτι καὶ τὰς ἐνστάσεις οὕτω φέρομεν πρὸς τοὺς οἰομένους ἀποδεικνύναι,
20 ὅτι οὐκ ἀνάγκη, ἂν οἰώμεθα ἢ ὅλως ἐνδέχεσθαι
ἄλλως ἢ ἕνεκά γε τοῦ λόγου. δῆλον δ' ἐκ τούτων καὶ ὅτι εὐήθεις
οἱ λαμβάνειν οἰόμενοι καλῶς τὰς ἀρχάς, ἐὰν ἔνδοξος
ᾖ ἡ πρότασις καὶ ἀληθής, οἷον οἱ σοφισταὶ ὅτι τὸ ἐπίστασθαι
τὸ ἐπιστήμην ἔχειν. οὐ γὰρ τὸ ἔνδοξον ἡμῖν ἀρχή ἐστιν,
25 ἀλλὰ τὸ πρῶτον τοῦ γένους περὶ ὃ δείκνυται· καὶ τἀληθὲς
οὐ πᾶν οἰκεῖον. ὅτι δ' ἐξ ἀναγκαίων εἶναι δεῖ τὸν συλλογισμόν,
φανερὸν καὶ ἐκ τῶνδε. εἰ γὰρ ὁ μὴ ἔχων λόγον τοῦ
διὰ τί οὔσης ἀποδείξεως οὐκ ἐπιστήμων, εἴη δ' ἂν ὥστε τὸ Α
κατὰ τοῦ Γ ἐξ ἀνάγκης ὑπάρχειν, τὸ δὲ Β τὸ μέσον, δι'
30 οὗ ἀπεδείχθη, μὴ ἐξ ἀνάγκης, οὐκ οἶδε διότι. οὐ γάρ ἐστι τοῦτο
διὰ τὸ μέσον· τὸ μὲν γὰρ ἐνδέχεται μὴ εἶναι, τὸ δὲ συμπέρασμα
ἀναγκαῖον. ἔτι εἴ τις μὴ οἶδε νῦν ἔχων τὸν λόγον
καὶ σῳζόμενος, σῳζομένου τοῦ πράγματος, μὴ ἐπιλελησμένος,
οὐδὲ πρότερον ᾔδει. φθαρείη δ' ἂν τὸ μέσον, εἰ μὴ
35 ἀναγκαῖον, ὥστε ἕξει μὲν τὸν λόγον σῳζόμενος σῳζομένου
τοῦ πράγματος, οὐκ οἶδε δέ. οὐδ' ἄρα πρότερον ᾔδει. εἰ δὲ
μὴ ἔφθαρται, ἐνδέχεται δὲ φθαρῆναι, τὸ συμβαῖνον ἂν εἴη
δυνατὸν καὶ ἐνδεχόμενον. ἀλλ' ἔστιν ἀδύνατον οὕτως ἔχοντα
εἰδέναι.
5Demonstrative knowledge must rest on necessary basic truths; for the object of scientific knowledge cannot be other than it is. Now attributes attaching essentially to their subjects attach necessarily to them: for essential attributes are either elements in the essential nature of their subjects, or contain their subjects as elements in their own essential nature. (The pairs of opposites which the latter class includes are necessary because one member or the other necessarily inheres.) 10It follows from this that premisses of the demonstrative syllogism must be connexions essential in the sense explained: for all attributes must inhere essentially or else be accidental, and accidental attributes are not necessary to their subjects.
We must either state the case thus, or else premise that the conclusion of demonstration is necessary and that a demonstrated conclusion cannot be other than it is, 15and then infer that the conclusion must be developed from necessary premisses. For though you may reason from true premisses without demonstrating, yet if your premisses are necessary you will assuredly demonstrate-in such necessity you have at once a distinctive character of demonstration. That demonstration proceeds from necessary premisses is also indicated by the fact that the objection we raise against a professed demonstration is 20that a premiss of it is not a necessary truth-whether we think it altogether devoid of necessity, or at any rate so far as our opponent's previous argument goes. This shows how naive it is to suppose one's basic truths rightly chosen if one starts with a proposition which is (1) popularly accepted and (2) true, such as the sophists' assumption that to know is the same as to possess knowledge. For (1) popular acceptance or rejection is no criterion of a basic truth, 25which can only be the primary law of the genus constituting the subject matter of the demonstration; and (2) not all truth is 'appropriate'.
A further proof that the conclusion must be the development of necessary premisses is as follows. Where demonstration is possible, one who can give no account which includes the cause has no scientific knowledge. If, then, we suppose a syllogism in which, though A necessarily inheres in C, yet B, the middle term 30of the demonstration, is not necessarily connected with A and C, then the man who argues thus has no reasoned knowledge of the conclusion, since this conclusion does not owe its necessity to the middle term; for though the conclusion is necessary, the mediating link is a contingent fact. Or again, if a man is without knowledge now, though he still retains the steps of the argument, though there is no change in himself or in the fact and no lapse of memory on his part; then neither had he knowledge previously. But the mediating link, 35not being necessary, may have perished in the interval; and if so, though there be no change in him nor in the fact, and though he will still retain the steps of the argument, yet he has not knowledge, and therefore had not knowledge before.
We must either state the case thus, or else premise that the conclusion of demonstration is necessary and that a demonstrated conclusion cannot be other than it is, 15and then infer that the conclusion must be developed from necessary premisses. For though you may reason from true premisses without demonstrating, yet if your premisses are necessary you will assuredly demonstrate-in such necessity you have at once a distinctive character of demonstration. That demonstration proceeds from necessary premisses is also indicated by the fact that the objection we raise against a professed demonstration is 20that a premiss of it is not a necessary truth-whether we think it altogether devoid of necessity, or at any rate so far as our opponent's previous argument goes. This shows how naive it is to suppose one's basic truths rightly chosen if one starts with a proposition which is (1) popularly accepted and (2) true, such as the sophists' assumption that to know is the same as to possess knowledge. For (1) popular acceptance or rejection is no criterion of a basic truth, 25which can only be the primary law of the genus constituting the subject matter of the demonstration; and (2) not all truth is 'appropriate'.
A further proof that the conclusion must be the development of necessary premisses is as follows. Where demonstration is possible, one who can give no account which includes the cause has no scientific knowledge. If, then, we suppose a syllogism in which, though A necessarily inheres in C, yet B, the middle term 30of the demonstration, is not necessarily connected with A and C, then the man who argues thus has no reasoned knowledge of the conclusion, since this conclusion does not owe its necessity to the middle term; for though the conclusion is necessary, the mediating link is a contingent fact. Or again, if a man is without knowledge now, though he still retains the steps of the argument, though there is no change in himself or in the fact and no lapse of memory on his part; then neither had he knowledge previously. But the mediating link, 35not being necessary, may have perished in the interval; and if so, though there be no change in him nor in the fact, and though he will still retain the steps of the argument, yet he has not knowledge, and therefore had not knowledge before.
75a
1 Ὅταν μὲν οὖν τὸ συμπέρασμα ἐξ ἀνάγκης ᾖ, οὐδὲν κωλύει
τὸ μέσον μὴ ἀναγκαῖον εἶναι δι' οὗ ἐδείχθη (ἔστι γὰρ
τὸ ἀναγκαῖον καὶ μὴ ἐξ ἀναγκαίων συλλογίσασθαι, ὥσπερ
καὶ ἀληθὲς μὴ ἐξ ἀληθῶν)· ὅταν δὲ τὸ μέσον ἐξ ἀνάγκης,
5 καὶ τὸ συμπέρασμα ἐξ ἀνάγκης, ὥσπερ καὶ ἐξ ἀληθῶν ἀληθὲς
ἀεί (ἔστω γὰρ τὸ Α κατὰ τοῦ Β ἐξ ἀνάγκης, καὶ τοῦτο
κατὰ τοῦ Γ· ἀναγκαῖον τοίνυν καὶ τὸ Α τῷ Γ ὑπάρχειν)·
ὅταν δὲ μὴ ἀναγκαῖον ᾖ τὸ συμπέρασμα, οὐδὲ τὸ μέσον
ἀναγκαῖον οἷόν τ' εἶναι (ἔστω γὰρ τὸ Α τῷ Γ μὴ ἐξ ἀνάγκης
10 ὑπάρχειν, τῷ δὲ Β, καὶ τοῦτο τῷ Γ ἐξ ἀνάγκης· καὶ
τὸ Α ἄρα τῷ Γ ἐξ ἀνάγκης ὑπάρξει· ἀλλ' οὐχ ὑπέκειτο).
Ἐπεὶ τοίνυν εἰ ἐπίσταται ἀποδεικτικῶς, δεῖ ἐξ ἀνάγκης ὑπάρχειν,
δῆλον ὅτι καὶ διὰ μέσου ἀναγκαίου δεῖ ἔχειν τὴν ἀπόδειξιν·
ἢ οὐκ ἐπιστήσεται οὔτε διότι οὔτε ὅτι ἀνάγκη ἐκεῖνο εἶναι,
15 ἀλλ' ἢ οἰήσεται οὐκ εἰδώς, ἐὰν ὑπολάβῃ ὡς ἀναγκαῖον
τὸ μὴ ἀναγκαῖον, ἢ οὐδ' οἰήσεται, ὁμοίως ἐάν τε τὸ ὅτι εἰδῇ
διὰ μέσων ἐάν τε τὸ διότι καὶ δι' ἀμέσων.
Τῶν δὲ συμβεβηκότων μὴ καθ' αὑτά, ὃν τρόπον διωρίσθη
τὰ καθ' αὑτά, οὐκ ἔστιν ἐπιστήμη ἀποδεικτική. οὐ γὰρ
20 ἔστιν ἐξ ἀνάγκης δεῖξαι τὸ συμπέρασμα· τὸ συμβεβηκὸς
γὰρ ἐνδέχεται μὴ ὑπάρχειν· περὶ τοῦ τοιούτου γὰρ λέγω συμβεβηκότος.
καίτοι ἀπορήσειεν ἄν τις ἴσως τίνος ἕνεκα ταῦτα
δεῖ ἐρωτᾶν περὶ τούτων, εἰ μὴ ἀνάγκη τὸ συμπέρασμα εἶναι·
οὐδὲν γὰρ διαφέρει εἴ τις ἐρόμενος τὰ τυχόντα εἶτα εἴπειεν τὸ
25 συμπέρασμα. δεῖ δ' ἐρωτᾶν οὐχ ὡς ἀναγκαῖον εἶναι διὰ τὰ
ἠρωτημένα, ἀλλ' ὅτι λέγειν ἀνάγκη τῷ ἐκεῖνα λέγοντι, καὶ
ἀληθῶς λέγειν, ἐὰν ἀληθῶς ᾖ ὑπάρχοντα.
Ἐπεὶ δ' ἐξ ἀνάγκης ὑπάρχει περὶ ἕκαστον γένος ὅσα
καθ' αὑτὰ ὑπάρχει καὶ ᾗ ἕκαστον, φανερὸν ὅτι περὶ τῶν
30 καθ' αὑτὰ ὑπαρχόντων αἱ ἐπιστημονικαὶ ἀποδείξεις καὶ ἐκ
τῶν τοιούτων εἰσίν. τὰ μὲν γὰρ συμβεβηκότα οὐκ ἀναγκαῖα,
ὥστ' οὐκ ἀνάγκη τὸ συμπέρασμα εἰδέναι διότι ὑπάρχει, οὐδ'
εἰ ἀεὶ εἴη, μὴ καθ' αὑτὸ δέ, οἷον οἱ διὰ σημείων συλλογισμοί.
τὸ γὰρ καθ' αὑτὸ οὐ καθ' αὑτὸ ἐπιστήσεται, οὐδὲ διότι
35 (τὸ δὲ διότι ἐπίστασθαί ἐστι τὸ διὰ τοῦ αἰτίου ἐπίστασθαι). δι'
αὑτὸ ἄρα δεῖ καὶ τὸ μέσον τῷ τρίτῳ καὶ τὸ πρῶτον τῷ μέσῳ
ὑπάρχειν.
1Even if the link has not actually perished but is liable to perish, this situation is possible and might occur. But such a condition cannot be knowledge.
When the conclusion is necessary, the middle through which it was proved may yet quite easily be non-necessary. You can in fact infer the necessary even from a non-necessary premiss, just as you can infer the true from the not true. On the other hand, when the middle is necessary 5the conclusion must be necessary; just as true premisses always give a true conclusion. Thus, if A is necessarily predicated of B and B of C, then A is necessarily predicated of C. But when the conclusion is nonnecessary the middle cannot be necessary either. Thus: let A be predicated non-necessarily of C 10but necessarily of B, and let B be a necessary predicate of C; then A too will be a necessary predicate of C, which by hypothesis it is not.
To sum up, then: demonstrative knowledge must be knowledge of a necessary nexus, and therefore must clearly be obtained through a necessary middle term; otherwise its possessor will know neither the cause nor the fact that his conclusion is a necessary connexion. 15Either he will mistake the non-necessary for the necessary and believe the necessity of the conclusion without knowing it, or else he will not even believe it-in which case he will be equally ignorant, whether he actually infers the mere fact through middle terms or the reasoned fact and from immediate premisses.
Of accidents that are not essential according to our definition of essential there is no demonstrative knowledge; for since an accident, in the sense in which I here speak of it, may also not inhere, 20it is impossible to prove its inherence as a necessary conclusion. A difficulty, however, might be raised as to why in dialectic, if the conclusion is not a necessary connexion, such and such determinate premisses should be proposed in order to deal with such and such determinate problems. Would not the result be the same if one asked any questions whatever and then merely stated one's 25conclusion? The solution is that determinate questions have to be put, not because the replies to them affirm facts which necessitate facts affirmed by the conclusion, but because these answers are propositions which if the answerer affirm, he must affirm the conclusion and affirm it with truth if they are true.
Since it is just those attributes within every genus which are essential and possessed by their respective subjects as such that are necessary it is clear that 30both the conclusions and the premisses of demonstrations which produce scientific knowledge are essential. For accidents are not necessary: and, further, since accidents are not necessary one does not necessarily have reasoned knowledge of a conclusion drawn from them (this is so even if the accidental premisses are invariable but not essential, as in proofs through signs; for though the conclusion be actually essential, one will not know it as essential nor know its reason); 35but to have reasoned knowledge of a conclusion is to know it through its cause. We may conclude that the middle must be consequentially connected with the minor, and the major with the middle.
When the conclusion is necessary, the middle through which it was proved may yet quite easily be non-necessary. You can in fact infer the necessary even from a non-necessary premiss, just as you can infer the true from the not true. On the other hand, when the middle is necessary 5the conclusion must be necessary; just as true premisses always give a true conclusion. Thus, if A is necessarily predicated of B and B of C, then A is necessarily predicated of C. But when the conclusion is nonnecessary the middle cannot be necessary either. Thus: let A be predicated non-necessarily of C 10but necessarily of B, and let B be a necessary predicate of C; then A too will be a necessary predicate of C, which by hypothesis it is not.
To sum up, then: demonstrative knowledge must be knowledge of a necessary nexus, and therefore must clearly be obtained through a necessary middle term; otherwise its possessor will know neither the cause nor the fact that his conclusion is a necessary connexion. 15Either he will mistake the non-necessary for the necessary and believe the necessity of the conclusion without knowing it, or else he will not even believe it-in which case he will be equally ignorant, whether he actually infers the mere fact through middle terms or the reasoned fact and from immediate premisses.
Of accidents that are not essential according to our definition of essential there is no demonstrative knowledge; for since an accident, in the sense in which I here speak of it, may also not inhere, 20it is impossible to prove its inherence as a necessary conclusion. A difficulty, however, might be raised as to why in dialectic, if the conclusion is not a necessary connexion, such and such determinate premisses should be proposed in order to deal with such and such determinate problems. Would not the result be the same if one asked any questions whatever and then merely stated one's 25conclusion? The solution is that determinate questions have to be put, not because the replies to them affirm facts which necessitate facts affirmed by the conclusion, but because these answers are propositions which if the answerer affirm, he must affirm the conclusion and affirm it with truth if they are true.
Since it is just those attributes within every genus which are essential and possessed by their respective subjects as such that are necessary it is clear that 30both the conclusions and the premisses of demonstrations which produce scientific knowledge are essential. For accidents are not necessary: and, further, since accidents are not necessary one does not necessarily have reasoned knowledge of a conclusion drawn from them (this is so even if the accidental premisses are invariable but not essential, as in proofs through signs; for though the conclusion be actually essential, one will not know it as essential nor know its reason); 35but to have reasoned knowledge of a conclusion is to know it through its cause. We may conclude that the middle must be consequentially connected with the minor, and the major with the middle.
Book 1,Chapter 7 (75a38–75b20)
Οὐκ ἄρα ἔστιν ἐξ ἄλλου γένους μεταβάντα δεῖξαι, οἷον
τὸ γεωμετρικὸν ἀριθμητικῇ. τρία γάρ ἐστι τὰ ἐν ταῖς ἀποδείξεσιν,
40 ἓν μὲν τὸ ἀποδεικνύμενον, τὸ συμπέρασμα (τοῦτο
δ' ἐστὶ τὸ ὑπάρχον γένει τινὶ καθ' αὑτό), ἓν δὲ τὰ ἐξιώματα
(ἀξιώματα δ' ἐστὶν ἐξ ὧν)· τρίτον τὸ γένος τὸ ὑποκείμενον,
38It follows that we cannot in demonstrating pass from one genus to another. We cannot, for instance, prove geometrical truths by arithmetic. For there are three elements in demonstration: 40(1) what is proved, the conclusion-an attribute inhering essentially in a genus; (2) the axioms, i.e. axioms which are premisses of demonstration; (3) the subject-genus whose attributes, i.e.
75b
1 οὗ τὰ πάθη καὶ τὰ καθ' αὑτὰ συμβεβηκότα δηλοῖ
ἡ ἀπόδειξις. ἐξ ὧν μὲν οὖν ἡ ἀπόδειξις, ἐνδέχεται τὰ αὐτὰ
εἶναι· ὧν δὲ τὸ γένος ἕτερον, ὥσπερ ἀριθμητικῆς καὶ γεωμετρίας,
οὐκ ἔστι τὴν ἀριθμητικὴν ἀπόδειξιν ἐφαρμόσαι ἐπὶ
5 τὰ τοῖς μεγέθεσι συμβεβηκότα, εἰ μὴ τὰ μεγέθη ἀριθμοί
εἰσι· τοῦτο δ' ὡς ἐνδέχεται ἐπί τινων, ὕστερον λεχθήσεται.
ἡ δ' ἀριθμητικὴ ἀπόδειξις ἀεὶ ἔχει τὸ γένος περὶ ὃ ἡ ἀπόδειξις,
καὶ αἱ ἄλλαι ὁμοίως. ὥστ' ἢ ἁπλῶς ἀνάγκη τὸ
αὐτὸ εἶναι γένος ἢ πῇ, εἰ μέλλει ἡ ἀπόδειξις μεταβαίνειν.
10 ἄλλως δ' ὅτι ἀδύνατον, δῆλον· ἐκ γὰρ τοῦ αὐτοῦ γένους
ἀνάγκη τὰ ἄκρα καὶ τὰ μέσα εἶναι. εἰ γὰρ μὴ καθ' αὑτά,
συμβεβηκότα ἔσται. διὰ τοῦτο τῇ γεωμετρίᾳ οὐκ ἔστι δεῖξαι
ὅτι τῶν ἐναντίων μία ἐπιστήμη, ἀλλ' οὐδ' ὅτι οἱ δύο κύβοι
κύβος· οὐδ' ἄλλῃ ἐπιστήμῃ τὸ ἑτέρας, ἀλλ' ἢ ὅσα οὕτως
15 ἔχει πρὸς ἄλληλα ὥστ' εἶναι θάτερον ὑπὸ θάτερον, οἷον τὰ
ὀπτικὰ πρὸς γεωμετρίαν καὶ τὰ ἁρμονικὰ πρὸς ἀριθμητικήν.
οὐδ' εἴ τι ὑπάρχει ταῖς γραμμαῖς μὴ ᾗ γραμμαὶ καὶ
ᾗ ἐκ τῶν ἀρχῶν τῶν ἰδίων, οἷον εἰ καλλίστη τῶν γραμμῶν
ἡ εὐθεῖα ἢ εἰ ἐναντίως ἔχει τῇ περιφερεῖ· οὐ γὰρ ᾗ τὸ
20 ἴδιον γένος αὐτῶν, ὑπάρχει, ἀλλ' ᾗ κοινόν τι.
1essential properties, are revealed by the demonstration. The axioms which are premisses of demonstration may be identical in two or more sciences: but in the case of two different genera such as arithmetic and geometry you cannot apply arithmetical demonstration 5to the properties of magnitudes unless the magnitudes in question are numbers. How in certain cases transference is possible I will explain later.
Arithmetical demonstration and the other sciences likewise possess, each of them, their own genera; so that if the demonstration is to pass from one sphere to another, the genus must be either absolutely or to some extent the same. 10If this is not so, transference is clearly impossible, because the extreme and the middle terms must be drawn from the same genus: otherwise, as predicated, they will not be essential and will thus be accidents. That is why it cannot be proved by geometry that opposites fall under one science, nor even that the product of two cubes is a cube. Nor can the theorem of any one science be demonstrated by means of another science, unless 15these theorems are related as subordinate to superior (e.g. as optical theorems to geometry or harmonic theorems to arithmetic). Geometry again cannot prove of lines any property which they do not possess qua lines, i.e. in virtue of the fundamental truths of their peculiar genus: it cannot show, for example, that the straight line is the most beautiful of lines or the contrary of the circle; for these qualities do not belong to lines 20in virtue of their peculiar genus, but through some property which it shares with other genera.
Arithmetical demonstration and the other sciences likewise possess, each of them, their own genera; so that if the demonstration is to pass from one sphere to another, the genus must be either absolutely or to some extent the same. 10If this is not so, transference is clearly impossible, because the extreme and the middle terms must be drawn from the same genus: otherwise, as predicated, they will not be essential and will thus be accidents. That is why it cannot be proved by geometry that opposites fall under one science, nor even that the product of two cubes is a cube. Nor can the theorem of any one science be demonstrated by means of another science, unless 15these theorems are related as subordinate to superior (e.g. as optical theorems to geometry or harmonic theorems to arithmetic). Geometry again cannot prove of lines any property which they do not possess qua lines, i.e. in virtue of the fundamental truths of their peculiar genus: it cannot show, for example, that the straight line is the most beautiful of lines or the contrary of the circle; for these qualities do not belong to lines 20in virtue of their peculiar genus, but through some property which it shares with other genera.
Book 1,Chapter 8 (75b21–36)
Φανερὸν δὲ καὶ ἐὰν ὦσιν αἱ προτάσεις καθόλου ἐξ ὧν
ὁ συλλογισμός, ὅτι ἀνάγκη καὶ τὸ συμπέρασμα ἀΐδιον
εἶναι τῆς τοιαύτης ἀποδείξεως καὶ τῆς ἁπλῶς εἰπεῖν ἀποδείξεως.
οὐκ ἔστιν ἄρα ἀπόδειξις τῶν φθαρτῶν οὐδ' ἐπιστήμη
25 ἁπλῶς, ἀλλ' οὕτως ὥσπερ κατὰ συμβεβηκός, ὅτι οὐ καθ'
ὅλου αὐτοῦ ἐστιν ἀλλὰ ποτὲ καὶ πώς. ὅταν δ' ᾖ, ἀνάγκη
τὴν ἑτέραν μὴ καθόλου εἶναι πρότασιν καὶ φθαρτήν—φθαρτὴν
μὲν ὅτι ἔσται καὶ τὸ συμπέρασμα οὔσης, μὴ καθόλου δὲ
ὅτι τῷ μὲν ἔσται τῷ δ' οὐκ ἔσται ἐφ' ὧν—ὥστ' οὐκ ἔστι συλλογίσασθαι
30 καθόλου, ἀλλ' ὅτι νῦν. ὁμοίως δ' ἔχει καὶ
περὶ ὁρισμούς, ἐπείπερ ἐστὶν ὁ ὁρισμὸς ἢ ἀρχὴ ἀποδείξεως
ἢ ἀπόδειξις θέσει διαφέρουσα ἢ συμπέρασμά τι ἀποδείξεως.
αἱ δὲ τῶν πολλάκις γινομένων ἀποδείξεις καὶ ἐπιστῆμαι, οἷον
σελήνης ἐκλείψεως, δῆλον ὅτι ᾗ μὲν τοιοῦδ' εἰσίν, ἀεὶ εἰσίν,
35 ᾗ δ' οὐκ ἀεί, κατὰ μέρος εἰσίν. ὥσπερ δ' ἡ ἔκλειψις, ὡσαύτως
τοῖς ἄλλοις.
21It is also clear that if the premisses from which the syllogism proceeds are commensurately universal, the conclusion of such i.e. in the unqualified sense-must also be eternal. Therefore no attribute can be demonstrated nor known by strictly scientific knowledge to inhere in perishable things. 25The proof can only be accidental, because the attribute's connexion with its perishable subject is not commensurately universal but temporary and special. If such a demonstration is made, one premiss must be perishable and not commensurately universal (perishable because only if it is perishable will the conclusion be perishable; not commensurately universal, because the predicate will be predicable of some instances of the subject and not of others); so that the conclusion can only be that a fact is true at the moment-30not commensurately and universally. The same is true of definitions, since a definition is either a primary premiss or a conclusion of a demonstration, or else only differs from a demonstration in the order of its terms. Demonstration and science of merely frequent occurrences-e.g. of eclipse as happening to the moon-are, as such, clearly eternal: 35whereas so far as they are not eternal they are not fully commensurate. Other subjects too have properties attaching to them in the same way as eclipse attaches to the moon.
Book 1,Chapter 9 (75b37–76a30)
Ἐπεὶ δὲ φανερὸν ὅτι ἕκαστον ἀποδεῖξαι οὐκ ἔστιν ἀλλ'
ἢ ἐκ τῶν ἑκάστου ἀρχῶν, ἂν τὸ δεικνύμενον ὑπάρχῃ ᾗ ἐκεῖνο,
οὐκ ἔστι τὸ ἐπίστασθαι τοῦτο, ἂν ἐξ ἀληθῶν καὶ ἀναποδείκτων
40 δειχθῇ καὶ ἀμέσων. ἔστι γὰρ οὕτω δεῖξαι, ὥσπερ Βρύσων
τὸν τετραγωνισμόν. κατὰ κοινόν τε γὰρ δεικνύουσιν οἱ τοιοῦτοι
λόγοι, ὃ καὶ ἑτέρῳ ὑπάρξει· διὸ καὶ ἐπ' ἄλλων ἐφαρμόττουσιν
37It is clear that if the conclusion is to show an attribute inhering as such, nothing can be demonstrated except from its 'appropriate' basic truths. Consequently a proof even from true, indemonstrable, 40and immediate premisses does not constitute knowledge. Such proofs are like Bryson's method of squaring the circle; for they operate by taking as their middle a common character-a character, therefore, which the subject may share with another-and consequently they apply equally to subjects different in kind.
76a
1 οἱ λόγοι οὐ συγγενῶν. οὐκοῦν οὐχ ᾗ ἐκεῖνο ἐπίσταται,
ἀλλὰ κατὰ συμβεβηκός· οὐ γὰρ ἂν ἐφήρμοττεν ἡ ἀπόδειξις
καὶ ἐπ' ἄλλο γένος.
Ἕκαστον δ' ἐπιστάμεθα μὴ κατὰ συμβεβηκός, ὅταν
5 κατ' ἐκεῖνο γινώσκωμεν καθ' ὃ ὑπάρχει, ἐκ τῶν ἀρχῶν
τῶν ἐκείνου ᾗ ἐκεῖνο, οἷον τὸ δυσὶν ὀρθαῖς ἴσας ἔχειν, ᾧ
ὑπάρχει καθ' αὑτὸ τὸ εἰρημένον, ἐκ τῶν ἀρχῶν τῶν τούτου.
ὥστ' εἰ καθ' αὑτὸ κἀκεῖνο ὑπάρχει ᾧ ὑπάρχει, ἀνάγκη
τὸ μέσον ἐν τῇ αὐτῇ συγγενείᾳ εἶναι. εἰ δὲ μή, ἀλλ' ὡς
10 τὰ ἁρμονικὰ δι' ἀριθμητικῆς. τὰ δὲ τοιαῦτα δείκνυται
μὲν ὡσαύτως, διαφέρει δέ· τὸ μὲν γὰρ ὅτι ἑτέρας ἐπιστήμης
(τὸ γὰρ ὑποκείμενον γένος ἕτερον), τὸ δὲ διότι τῆς ἄνω,
ἧς καθ' αὑτὰ τὰ πάθη ἐστίν. ὥστε καὶ ἐκ τούτων φανερὸν
ὅτι οὐκ ἔστιν ἀποδεῖξαι ἕκαστον ἁπλῶς ἀλλ' ἢ ἐκ τῶν ἑκάστου
15 ἀρχῶν. ἀλλὰ τούτων αἱ ἀρχαὶ ἔχουσι τὸ κοινόν.
Εἰ δὲ φανερὸν τοῦτο, φανερὸν καὶ ὅτι οὐκ ἔστι τὰς ἑκάστου
ἰδίας ἀρχὰς ἀποδεῖξαι· ἔσονται γὰρ ἐκεῖναι ἁπάντων
ἀρχαί, καὶ ἐπιστήμη ἡ ἐκείνων κυρία πάντων. καὶ γὰρ ἐπίσταται
μᾶλλον ὁ ἐκ τῶν ἀνώτερον αἰτίων εἰδώς· ἐκ τῶν
20 προτέρων γὰρ οἶδεν, ὅταν ἐκ μὴ αἰτιατῶν εἰδῇ αἰτίων. ὥστ'
εἰ μᾶλλον οἶδε καὶ μάλιστα, κἂν ἐπιστήμη ἐκείνη εἴη καὶ
μᾶλλον καὶ μάλιστα. ἡ δ' ἀπόδειξις οὐκ ἐφαρμόττει ἐπ'
ἄλλο γένος, ἀλλ' ἢ ὡς εἴρηται αἱ γεωμετρικαὶ ἐπὶ τὰς
μηχανικὰς ἢ ὀπτικὰς καὶ αἱ ἀριθμητικαὶ ἐπὶ τὰς ἁρμονικάς.
25
Χαλεπὸν δ' ἐστὶ τὸ γνῶναι εἰ οἶδεν ἢ μή. χαλεπὸν
γὰρ τὸ γνῶναι εἰ ἐκ τῶν ἑκάστου ἀρχῶν ἴσμεν ἢ μή· ὅπερ
ἐστὶ τὸ εἰδέναι. οἰόμεθα δ', ἂν ἔχωμεν ἐξ ἀληθινῶν τινῶν
συλλογισμὸν καὶ πρώτων, ἐπίστασθαι. τὸ δ' οὐκ ἔστιν, ἀλλὰ
30 συγγενῆ δεῖ εἶναι τοῖς πρώτοις.
1They therefore afford knowledge of an attribute only as inhering accidentally, not as belonging to its subject as such: otherwise they would not have been applicable to another genus.
Our knowledge of any attribute's connexion with a subject is accidental unless 5we know that connexion through the middle term in virtue of which it inheres, and as an inference from basic premisses essential and 'appropriate' to the subject-unless we know, e.g. the property of possessing angles equal to two right angles as belonging to that subject in which it inheres essentially, and as inferred from basic premisses essential and 'appropriate' to that subject: so that if that middle term also belongs essentially to the minor, the middle must belong to the same kind as the major and minor terms. The only exceptions to this rule are such cases as theorems in harmonics which are demonstrable by arithmetic. 10Such theorems are proved by the same middle terms as arithmetical properties, but with a qualification-the fact falls under a separate science (for the subject genus is separate), but the reasoned fact concerns the superior science, to which the attributes essentially belong. Thus, even these apparent exceptions show that no attribute is strictly demonstrable except from its 'appropriate' basic truths, 15which, however, in the case of these sciences have the requisite identity of character.
It is no less evident that the peculiar basic truths of each inhering attribute are indemonstrable; for basic truths from which they might be deduced would be basic truths of all that is, and the science to which they belonged would possess universal sovereignty. This is so because he knows better whose knowledge is deduced from higher causes, 20for his knowledge is from prior premisses when it derives from causes themselves uncaused: hence, if he knows better than others or best of all, his knowledge would be science in a higher or the highest degree. But, as things are, demonstration is not transferable to another genus, with such exceptions as we have mentioned of the application of geometrical demonstrations to theorems 25in mechanics or optics, or of arithmetical demonstrations to those of harmonics.
It is hard to be sure whether one knows or not; for it is hard to be sure whether one's knowledge is based on the basic truths appropriate to each attribute-the differentia of true knowledge. We think we have scientific knowledge if we have reasoned from true and primary premisses. But that is not so: 30the conclusion must be homogeneous with the basic facts of the science.
Our knowledge of any attribute's connexion with a subject is accidental unless 5we know that connexion through the middle term in virtue of which it inheres, and as an inference from basic premisses essential and 'appropriate' to the subject-unless we know, e.g. the property of possessing angles equal to two right angles as belonging to that subject in which it inheres essentially, and as inferred from basic premisses essential and 'appropriate' to that subject: so that if that middle term also belongs essentially to the minor, the middle must belong to the same kind as the major and minor terms. The only exceptions to this rule are such cases as theorems in harmonics which are demonstrable by arithmetic. 10Such theorems are proved by the same middle terms as arithmetical properties, but with a qualification-the fact falls under a separate science (for the subject genus is separate), but the reasoned fact concerns the superior science, to which the attributes essentially belong. Thus, even these apparent exceptions show that no attribute is strictly demonstrable except from its 'appropriate' basic truths, 15which, however, in the case of these sciences have the requisite identity of character.
It is no less evident that the peculiar basic truths of each inhering attribute are indemonstrable; for basic truths from which they might be deduced would be basic truths of all that is, and the science to which they belonged would possess universal sovereignty. This is so because he knows better whose knowledge is deduced from higher causes, 20for his knowledge is from prior premisses when it derives from causes themselves uncaused: hence, if he knows better than others or best of all, his knowledge would be science in a higher or the highest degree. But, as things are, demonstration is not transferable to another genus, with such exceptions as we have mentioned of the application of geometrical demonstrations to theorems 25in mechanics or optics, or of arithmetical demonstrations to those of harmonics.
It is hard to be sure whether one knows or not; for it is hard to be sure whether one's knowledge is based on the basic truths appropriate to each attribute-the differentia of true knowledge. We think we have scientific knowledge if we have reasoned from true and primary premisses. But that is not so: 30the conclusion must be homogeneous with the basic facts of the science.
Book 1,Chapter 10 (76a31–77a4)
Λέγω δ' ἀρχὰς ἐν ἑκάστῳ γένει ταύτας ἃς ὅτι ἔστι
μὴ ἐνδέχεται δεῖξαι. τί μὲν οὖν σημαίνει καὶ τὰ πρῶτα καὶ
τὰ ἐκ τούτων, λαμβάνεται, ὅτι δ' ἔστι, τὰς μὲν ἀρχὰς
ἀνάγκη λαμβάνειν, τὰ δ' ἄλλα δεικνύναι· οἷον τί μονὰς
35 ἢ τί τὸ εὐθὺ καὶ τρίγωνον, εἶναι δὲ τὴν μονάδα λαβεῖν καὶ
μέγεθος, τὰ δ' ἕτερα δεικνύναι.
Ἔστι δ' ὧν χρῶνται ἐν ταῖς ἀποδεικτικαῖς ἐπιστήμαις
τὰ μὲν ἴδια ἑκάστης ἐπιστήμης τὰ δὲ κοινά, κοινὰ δὲ κατ'
ἀναλογίαν, ἐπεὶ χρήσιμόν γε ὅσον ἐν τῷ ὑπὸ τὴν ἐπιστήμην
40 γένει· ἴδια μὲν οἷον γραμμὴν εἶναι τοιανδὶ καὶ τὸ εὐθύ,
κοινὰ δὲ οἷον τὸ ἴσα ἀπὸ ἴσων ἂν ἀφέλῃ, ὅτι ἴσα τὰ λοιπά.
ἱκανὸν δ' ἕκαστον τούτων ὅσον ἐν τῷ γένει· ταὐτὸ γὰρ ποιήσει,
31I call the basic truths of every genus those clements in it the existence of which cannot be proved. As regards both these primary truths and the attributes dependent on them the meaning of the name is assumed. The fact of their existence as regards the primary truths must be assumed; but it has to be proved of the remainder, the attributes. Thus we assume the meaning alike of unity, 35straight, and triangular; but while as regards unity and magnitude we assume also the fact of their existence, in the case of the remainder proof is required.
Of the basic truths used in the demonstrative sciences some are peculiar to each science, and some are common, but common only in the sense of analogous, being of use only in so far as they fall within the genus constituting the province of the science in question.
40Peculiar truths are, e.g. the definitions of line and straight; common truths are such as 'take equals from equals and equals remain'.
Of the basic truths used in the demonstrative sciences some are peculiar to each science, and some are common, but common only in the sense of analogous, being of use only in so far as they fall within the genus constituting the province of the science in question.
40Peculiar truths are, e.g. the definitions of line and straight; common truths are such as 'take equals from equals and equals remain'.
76b
1 κἂν μὴ κατὰ πάντων λάβῃ ἀλλ' ἐπὶ μεγεθῶν μόνον,
τῷ δ' ἀριθμητικῷ ἐπ' ἀριθμῶν.
Ἔστι δ' ἴδια μὲν καὶ ἃ λαμβάνεται εἶναι, περὶ ἃ ἡ
ἐπιστήμη θεωρεῖ τὰ ὑπάρχοντα καθ' αὑτά, οἷον μονάδας ἡ
5 ἀριθμητική, ἡ δὲ γεωμετρία σημεῖα καὶ γραμμάς. ταῦτα
γὰρ λαμβάνουσι τὸ εἶναι καὶ τοδὶ εἶναι. τὰ δὲ τούτων πάθη
καθ' αὑτά, τί μὲν σημαίνει ἕκαστον, λαμβάνουσιν, οἷον ἡ
μὲν ἀριθμητικὴ τί περιττὸν ἢ ἄρτιον ἢ τετράγωνον ἢ κύβος,
ἡ δὲ γεωμετρία τί τὸ ἄλογον ἢ τὸ κεκλάσθαι ἢ νεύειν, ὅτι
10 δ' ἔστι, δεικνύουσι διά τε τῶν κοινῶν καὶ ἐκ τῶν ἀποδεδειγμένων.
καὶ ἡ ἀστρολογία ὡσαύτως. πᾶσα γὰρ ἀποδεικτικὴ
ἐπιστήμη περὶ τρία ἐστίν, ὅσα τε εἶναι τίθεται (ταῦτα δ'
ἐστὶ τὸ γένος, οὗ τῶν καθ' αὑτὰ παθημάτων ἐστὶ θεωρητική),
καὶ τὰ κοινὰ λεγόμενα ἀξιώματα, ἐξ ὧν πρώτων ἀποδείκνυσι,
15 καὶ τρίτον τὰ πάθη, ὧν τί σημαίνει ἕκαστον λαμβάνει.
ἐνίας μέντοι ἐπιστήμας οὐδὲν κωλύει ἔνια τούτων παρορᾶν,
οἷον τὸ γένος μὴ ὑποτίθεσθαι εἶναι, ἂν ᾖ φανερὸν ὅτι
ἔστιν (οὐ γὰρ ὁμοίως δῆλον ὅτι ἀριθμὸς ἔστι καὶ ὅτι ψυχρὸν
καὶ θερμόν), καὶ τὰ πάθη μὴ λαμβάνειν τί σημαίνει, ἂν ᾖ δῆλα·
20 ὥσπερ οὐδὲ τὰ κοινὰ οὐ λαμβάνει τί σημαίνει τὸ ἴσα ἀπὸ
ἴσων ἀφελεῖν, ὅτι γνώριμον. ἀλλ' οὐδὲν ἧττον τῇ γε φύσει τρία
ταῦτά ἐστι, περὶ ὅ τε δείκνυσι καὶ ἃ δείκνυσι καὶ ἐξ ὧν.
Οὐκ ἔστι δ' ὑπόθεσις οὐδ' αἴτημα, ὃ ἀνάγκη εἶναι δι'
αὑτὸ καὶ δοκεῖν ἀνάγκη. οὐ γὰρ πρὸς τὸν ἔξω λόγον ἡ ἀπόδειξις,
25 ἀλλὰ πρὸς τὸν ἐν τῇ ψυχῇ, ἐπεὶ οὐδὲ συλλογισμός.
ἀεὶ γὰρ ἔστιν ἐνστῆναι πρὸς τὸν ἔξω λόγον, ἀλλὰ πρὸς τὸν
ἔσω λόγον οὐκ ἀεί. ὅσα μὲν οὖν δεικτὰ ὄντα λαμβάνει αὐτὸς
μὴ δείξας, ταῦτ', ἐὰν μὲν δοκοῦντα λαμβάνῃ τῷ μανθάνοντι,
ὑποτίθεται, καὶ ἔστιν οὐχ ἁπλῶς ὑπόθεσις ἀλλὰ
30 πρὸς ἐκεῖνον μόνον, ἂν δὲ ἢ μηδεμιᾶς ἐνούσης δόξης ἢ καὶ
ἐναντίας ἐνούσης λαμβάνῃ τὸ αὐτό, αἰτεῖται. καὶ τούτῳ διαφέρει
ὑπόθεσις καὶ αἴτημα· ἔστι γὰρ αἴτημα τὸ ὑπεναντίον
τοῦ μανθάνοντος τῇ δόξῃ, ἢ ὃ ἄν τις ἀποδεικτὸν ὂν λαμβάνῃ
καὶ χρῆται μὴ δείξας.
35 Οἱ μὲν οὖν ὅροι οὐκ εἰσὶν ὑποθέσεις (οὐδὲν γὰρ εἶναι ἢ μὴ
λέγεται), ἀλλ' ἐν ταῖς προτάσεσιν αἱ ὑποθέσεις, τοὺς δ'
ὅρους μόνον ξυνίεσθαι δεῖ· τοῦτο δ' οὐχ ὑπόθεσις (εἰ μὴ καὶ
τὸ ἀκούειν ὑπόθεσίν τις εἶναι φήσει), ἀλλ' ὅσων ὄντων τῷ
ἐκεῖνα εἶναι γίνεται τὸ συμπέρασμα. (οὐδ' ὁ γεωμέτρης ψευδῆ
40 ὑποτίθεται, ὥσπερ τινὲς ἔφασαν, λέγοντες ὡς οὐ δεῖ τῷ ψεύδει
χρῆσθαι, τὸν δὲ γεωμέτρην ψεύδεσθαι λέγοντα ποδιαίαν
τὴν οὐ ποδιαίαν ἢ εὐθεῖαν τὴν γεγραμμένην οὐκ εὐθεῖαν
1Only so much of these common truths is required as falls within the genus in question: for a truth of this kind will have the same force even if not used generally but applied by the geometer only to magnitudes, or by the arithmetician only to numbers. Also peculiar to a science are the subjects the existence as well as the meaning of which it assumes, and the essential attributes of which it investigates, e.g. 5in arithmetic units, in geometry points and lines. Both the existence and the meaning of the subjects are assumed by these sciences; but of their essential attributes only the meaning is assumed. For example arithmetic assumes the meaning of odd and even, square and cube, geometry that of incommensurable, or of deflection or verging of lines, whereas 10the existence of these attributes is demonstrated by means of the axioms and from previous conclusions as premisses. Astronomy too proceeds in the same way. For indeed every demonstrative science has three elements: (1) that which it posits, the subject genus whose essential attributes it examines; (2) the so-called axioms, which are primary premisses of its demonstration; 15(3) the attributes, the meaning of which it assumes. Yet some sciences may very well pass over some of these elements; e.g. we might not expressly posit the existence of the genus if its existence were obvious (for instance, the existence of hot and cold is more evident than that of number); or we might omit to assume expressly the meaning of the attributes if it were well understood. 20In the way the meaning of axioms, such as 'Take equals from equals and equals remain', is well known and so not expressly assumed. Nevertheless in the nature of the case the essential elements of demonstration are three: the subject, the attributes, and the basic premisses.
That which expresses necessary self-grounded fact, and which we must necessarily believe, is distinct both from the hypotheses of a science and from illegitimate postulate-I say 'must believe', because all syllogism, and therefore a fortiori demonstration, is addressed not to the spoken word, 25but to the discourse within the soul, and though we can always raise objections to the spoken word, to the inward discourse we cannot always object. That which is capable of proof but assumed by the teacher without proof is, if the pupil believes and accepts it, hypothesis, though only in a limited sense hypothesis-that is, 30relatively to the pupil; if the pupil has no opinion or a contrary opinion on the matter, the same assumption is an illegitimate postulate. Therein lies the distinction between hypothesis and illegitimate postulate: the latter is the contrary of the pupil's opinion, demonstrable, but assumed and used without demonstration.
35The definition-viz. those which are not expressed as statements that anything is or is not-are not hypotheses: but it is in the premisses of a science that its hypotheses are contained. Definitions require only to be understood, and this is not hypothesis-unless it be contended that the pupil's hearing is also an hypothesis required by the teacher. Hypotheses, on the contrary, postulate facts on the being of which depends the being of the fact inferred. 40Nor are the geometer's hypotheses false, as some have held, urging that one must not employ falsehood and that the geometer is uttering falsehood in stating that the line which he draws is a foot long or straight, when it is actually neither.
That which expresses necessary self-grounded fact, and which we must necessarily believe, is distinct both from the hypotheses of a science and from illegitimate postulate-I say 'must believe', because all syllogism, and therefore a fortiori demonstration, is addressed not to the spoken word, 25but to the discourse within the soul, and though we can always raise objections to the spoken word, to the inward discourse we cannot always object. That which is capable of proof but assumed by the teacher without proof is, if the pupil believes and accepts it, hypothesis, though only in a limited sense hypothesis-that is, 30relatively to the pupil; if the pupil has no opinion or a contrary opinion on the matter, the same assumption is an illegitimate postulate. Therein lies the distinction between hypothesis and illegitimate postulate: the latter is the contrary of the pupil's opinion, demonstrable, but assumed and used without demonstration.
35The definition-viz. those which are not expressed as statements that anything is or is not-are not hypotheses: but it is in the premisses of a science that its hypotheses are contained. Definitions require only to be understood, and this is not hypothesis-unless it be contended that the pupil's hearing is also an hypothesis required by the teacher. Hypotheses, on the contrary, postulate facts on the being of which depends the being of the fact inferred. 40Nor are the geometer's hypotheses false, as some have held, urging that one must not employ falsehood and that the geometer is uttering falsehood in stating that the line which he draws is a foot long or straight, when it is actually neither.
77a
1 οὖσαν. ὁ δὲ γεωμέτρης οὐδὲν συμπεραίνεται τῷ τήνδε εἶναι
γραμμὴν ἣν αὐτὸς ἔφθεγκται, ἀλλὰ τὰ διὰ τούτων δηλούμενα.)
ἔτι τὸ αἴτημα καὶ ὑπόθεσις πᾶσα ἢ ὡς ὅλον ἢ ὡς
ἐν μέρει, οἱ δ' ὅροι οὐδέτερον τούτων.
1The truth is that the geometer does not draw any conclusion from the being of the particular line of which he speaks, but from what his diagrams symbolize. A further distinction is that all hypotheses and illegitimate postulates are either universal or particular, whereas a definition is neither.
Book 1,Chapter 11 (77a5–35)
5 Εἴδη μὲν οὖν εἶναι ἢ ἕν τι παρὰ τὰ πολλὰ οὐκ ἀνάγκη,
εἰ ἀπόδειξις ἔσται, εἶναι μέντοι ἓν κατὰ πολλῶν ἀληθὲς εἰπεῖν
ἀνάγκη· οὐ γὰρ ἔσται τὸ καθόλου, ἂν μὴ τοῦτο ᾖ· ἐὰν
δὲ τὸ καθόλου μὴ ᾖ, τὸ μέσον οὐκ ἔσται, ὥστ' οὐδ' ἀπόδειξις.
δεῖ ἄρα τι ἓν καὶ τὸ αὐτὸ ἐπὶ πλειόνων εἶναι μὴ ὁμώνυμον.
10 τὸ δὲ μὴ ἐνδέχεσθαι ἅμα φάναι καὶ ἀποφάναι οὐδεμία
λαμβάνει ἀπόδειξις, ἀλλ' ἢ ἐὰν δέῃ δεῖξαι καὶ τὸ συμπέρασμα
οὕτως. δείκνυται δὲ λαβοῦσι τὸ πρῶτον κατὰ τοῦ μέσου,
ὅτι ἀληθές, ἀποφάναι δ' οὐκ ἀληθές. τὸ δὲ μέσον οὐδὲν
διαφέρει εἶναι καὶ μὴ εἶναι λαβεῖν, ὡς δ' αὔτως καὶ
15 τὸ τρίτον. εἰ γὰρ ἐδόθη, καθ' οὗ ἄνθρωπον ἀληθὲς εἰπεῖν, εἰ
καὶ μὴ ἄνθρωπον ἀληθές, ἀλλ' εἰ μόνον ἄνθρωπον ζῷον εἶναι,
μὴ ζῷον δὲ μή, ἔσται [γὰρ] ἀληθὲς εἰπεῖν Καλλίαν, εἰ
καὶ μὴ Καλλίαν, ὅμως ζῷον, μὴ ζῷον δ' οὔ. αἴτιον δ' ὅτι
τὸ πρῶτον οὐ μόνον κατὰ τοῦ μέσου λέγεται ἀλλὰ καὶ κατ'
20 ἄλλου διὰ τὸ εἶναι ἐπὶ πλειόνων, ὥστ' οὐδ' εἰ τὸ μέσον καὶ
αὐτό ἐστι καὶ μὴ αὐτό, πρὸς τὸ συμπέρασμα οὐδὲν διαφέρει.
τὸ δ' ἅπαν φάναι ἢ ἀποφάναι ἡ εἰς τὸ ἀδύνατον ἀπόδειξις
λαμβάνει, καὶ ταῦτα οὐδ' ἀεὶ καθόλου, ἀλλ' ὅσον ἱκανόν,
ἱκανὸν δ' ἐπὶ τοῦ γένους. λέγω δ' ἐπὶ τοῦ γένους οἷον περὶ
25 ὃ γένος τὰς ἀποδείξεις φέρει, ὥσπερ εἴρηται καὶ πρότερον.
Ἐπικοινωνοῦσι δὲ πᾶσαι αἱ ἐπιστῆμαι ἀλλήλαις κατὰ
τὰ κοινά (κοινὰ δὲ λέγω οἷς χρῶνται ὡς ἐκ τούτων ἀποδεικνύντες,
ἀλλ' οὐ περὶ ὧν δεικνύουσιν οὐδ' ὃ δεικνύουσιν),
καὶ ἡ διαλεκτικὴ πάσαις, καὶ εἴ τις καθόλου πειρῷτο δεικνύναι
30 τὰ κοινά, οἷον ὅτι ἅπαν φάναι ἢ ἀποφάναι, ἢ ὅτι
ἴσα ἀπὸ ἴσων, ἢ τῶν τοιούτων ἄττα. ἡ δὲ διαλεκτικὴ οὐκ ἔστιν
οὕτως ὡρισμένων τινῶν, οὐδὲ γένους τινὸς ἑνός. οὐ γὰρ ἂν ἠρώτα·
ἀποδεικνύντα γὰρ οὐκ ἔστιν ἐρωτᾶν διὰ τὸ τῶν ἀντικειμένων
ὄντων μὴ δείκνυσθαι τὸ αὐτό. δέδεικται δὲ τοῦτο ἐν τοῖς
35 περὶ συλλογισμοῦ.
5So demonstration does not necessarily imply the being of Forms nor a One beside a Many, but it does necessarily imply the possibility of truly predicating one of many; since without this possibility we cannot save the universal, and if the universal goes, the middle term goes witb. it, and so demonstration becomes impossible. We conclude, then, that there must be a single identical term unequivocally predicable of a number of individuals.
10The law that it is impossible to affirm and deny simultaneously the same predicate of the same subject is not expressly posited by any demonstration except when the conclusion also has to be expressed in that form; in which case the proof lays down as its major premiss that the major is truly affirmed of the middle but falsely denied. It makes no difference, however, if we add to the middle, or again to the minor term, the corresponding negative. 15For grant a minor term of which it is true to predicate man-even if it be also true to predicate not-man of it--still grant simply that man is animal and not not-animal, and the conclusion follows: for it will still be true to say that Callias--even if it be also true to say that not-Callias--is animal and not not-animal. The reason is that the major term is predicable not only of the middle, 20but of something other than the middle as well, being of wider application; so that the conclusion is not affected even if the middle is extended to cover the original middle term and also what is not the original middle term.
The law that every predicate can be either truly affirmed or truly denied of every subject is posited by such demonstration as uses reductio ad impossibile, and then not always universally, but so far as it is requisite; within the limits, that is, of the genus-the genus, I mean (as I have already explained), 25to which the man of science applies his demonstrations. In virtue of the common elements of demonstration-I mean the common axioms which are used as premisses of demonstration, not the subjects nor the attributes demonstrated as belonging to them-all the sciences have communion with one another, and in communion with them all is dialectic and any science which might attempt a universal proof 30of axioms such as the law of excluded middle, the law that the subtraction of equals from equals leaves equal remainders, or other axioms of the same kind. Dialectic has no definite sphere of this kind, not being confined to a single genus. Otherwise its method would not be interrogative; for the interrogative method is barred to the demonstrator, who cannot use the opposite facts to prove the same nexus. This was shown in my work 35on the syllogism.
10The law that it is impossible to affirm and deny simultaneously the same predicate of the same subject is not expressly posited by any demonstration except when the conclusion also has to be expressed in that form; in which case the proof lays down as its major premiss that the major is truly affirmed of the middle but falsely denied. It makes no difference, however, if we add to the middle, or again to the minor term, the corresponding negative. 15For grant a minor term of which it is true to predicate man-even if it be also true to predicate not-man of it--still grant simply that man is animal and not not-animal, and the conclusion follows: for it will still be true to say that Callias--even if it be also true to say that not-Callias--is animal and not not-animal. The reason is that the major term is predicable not only of the middle, 20but of something other than the middle as well, being of wider application; so that the conclusion is not affected even if the middle is extended to cover the original middle term and also what is not the original middle term.
The law that every predicate can be either truly affirmed or truly denied of every subject is posited by such demonstration as uses reductio ad impossibile, and then not always universally, but so far as it is requisite; within the limits, that is, of the genus-the genus, I mean (as I have already explained), 25to which the man of science applies his demonstrations. In virtue of the common elements of demonstration-I mean the common axioms which are used as premisses of demonstration, not the subjects nor the attributes demonstrated as belonging to them-all the sciences have communion with one another, and in communion with them all is dialectic and any science which might attempt a universal proof 30of axioms such as the law of excluded middle, the law that the subtraction of equals from equals leaves equal remainders, or other axioms of the same kind. Dialectic has no definite sphere of this kind, not being confined to a single genus. Otherwise its method would not be interrogative; for the interrogative method is barred to the demonstrator, who cannot use the opposite facts to prove the same nexus. This was shown in my work 35on the syllogism.
Book 1,Chapter 12 (77a36–78a21)
Εἰ δὲ τὸ αὐτό ἐστιν ἐρώτημα συλλογιστικὸν καὶ πρότασις
ἀντιφάσεως, προτάσεις δὲ καθ' ἑκάστην ἐπιστήμην
ἐξ ὧν ὁ συλλογισμὸς ὁ καθ' ἑκάστην, εἴη ἄν τι ἐρώτημα
ἐπιστημονικόν, ἐξ ὧν ὁ καθ' ἑκάστην οἰκεῖος γίνεται συλλογισμός.
40 δῆλον ἄρα ὅτι οὐ πᾶν ἐρώτημα γεωμετρικὸν ἂν
εἴη οὐδ' ἰατρικόν, ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων· ἀλλ' ἐξ
36If a syllogistic question is equivalent to a proposition embodying one of the two sides of a contradiction, and if each science has its peculiar propositions from which its peculiar conclusion is developed, then there is such a thing as a distinctively scientific question, and it is the interrogative form of the premisses from which the 'appropriate' conclusion of each science is developed.
77b
1 ὧν δείκνυταί τι περὶ ὧν ἡ γεωμετρία ἐστίν, ἢ ἃ ἐκ τῶν
αὐτῶν δείκνυται τῇ γεωμετρίᾳ, ὥσπερ τὰ ὀπτικά. ὁμοίως
δὲ καὶ ἐπὶ τῶν ἄλλων. καὶ περὶ μὲν τούτων καὶ λόγον ὑφεκτέον
ἐκ τῶν γεωμετρικῶν ἀρχῶν καὶ συμπερασμάτων,
5 περὶ δὲ τῶν ἀρχῶν λόγον οὐχ ὑφεκτέον τῷ γεωμέτρῃ ᾗ
γεωμέτρης· ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων ἐπιστημῶν. οὔτε
πᾶν ἄρα ἕκαστον ἐπιστήμονα ἐρώτημα ἐρωτητέον, οὔθ' ἅπαν
τὸ ἐρωτώμενον ἀποκριτέον περὶ ἑκάστου, ἀλλὰ τὰ κατὰ τὴν
ἐπιστήμην διορισθέντα. εἰ δὲ διαλέξεται γεωμέτρῃ ᾗ γεωμέτρης
10 οὕτως, φανερὸν ὅτι καὶ καλῶς, ἐὰν ἐκ τούτων τι
δεικνύῃ· εἰ δὲ μή, οὐ καλῶς. δῆλον δ' ὅτι οὐδ' ἐλέγχει
γεωμέτρην ἀλλ' ἢ κατὰ συμβεβηκός· ὥστ' οὐκ ἂν εἴη ἐν
ἀγεωμετρήτοις περὶ γεωμετρίας διαλεκτέον· λήσει γὰρ ὁ
φαύλως διαλεγόμενος. ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων ἔχει
15 ἐπιστημῶν.
Ἐπεὶ δ' ἔστι γεωμετρικὰ ἐρωτήματα, ἆρ' ἔστι καὶ
ἀγεωμέτρητα; καὶ παρ' ἑκάστην ἐπιστήμην τὰ κατὰ τὴν
ἄγνοιαν τὴν ποίαν γεωμετρικά ἐστιν; καὶ πότερον
ὁ κατὰ τὴν ἄγνοιαν συλλογισμὸς ὁ ἐκ τῶν ἀντικειμένων
20 συλλογισμός, ἢ ὁ παραλογισμός, κατὰ γεωμετρίαν
δέ, ἢ <ὁ> ἐξ ἄλλης τέχνης, οἷον τὸ μουσικόν ἐστιν ἐρώτημα
ἀγεωμέτρητον περὶ γεωμετρίας, τὸ δὲ τὰς παραλλήλους
συμπίπτειν οἴεσθαι γεωμετρικόν πως καὶ ἀγεωμέτρητον ἄλλον
τρόπον; διττὸν γὰρ τοῦτο, ὥσπερ τὸ ἄρρυθμον, καὶ τὸ
25 μὲν ἕτερον ἀγεωμέτρητον τῷ μὴ ἔχειν [ὥσπερ τὸ ἄρρυθμον],
τὸ δ' ἕτερον τῷ φαύλως ἔχειν· καὶ ἡ ἄγνοια αὕτη καὶ ἡ ἐκ
τῶν τοιούτων ἀρχῶν ἐναντία. ἐν δὲ τοῖς μαθήμασιν οὐκ ἔστιν
ὁμοίως ὁ παραλογισμός, ὅτι τὸ μέσον ἐστὶν ἀεὶ τὸ διττόν·
κατά τε γὰρ τούτου παντός, καὶ τοῦτο πάλιν κατ' ἄλλου
30 λέγεται παντός (τὸ δὲ κατηγορούμενον οὐ λέγεται πᾶν), ταῦτα
δ' ἔστιν οἷον ὁρᾶν τῇ νοήσει, ἐν δὲ τοῖς λόγοις λανθάνει. ἆρα
πᾶς κύκλος σχῆμα; ἂν δὲ γράψῃ, δῆλον. τί δέ; τὰ ἔπη
κύκλος; φανερὸν ὅτι οὐκ ἔστιν.
Οὐ δεῖ δ' ἔνστασιν εἰς αὐτὸ φέρειν, ἂν ᾖ ἡ πρότασις
35 ἐπακτική. ὥσπερ γὰρ οὐδὲ πρότασίς ἐστιν ἣ μὴ ἔστιν ἐπὶ
πλειόνων (οὐ γὰρ ἔσται ἐπὶ πάντων, ἐκ τῶν καθόλου δ' ὁ
συλλογισμός), δῆλον ὅτι οὐδ' ἔνστασις. αἱ αὐταὶ γὰρ προτάσεις
καὶ ἐνστάσεις· ἣν γὰρ φέρει ἔνστασιν, αὕτη γένοιτ'
ἂν πρότασις ἢ ἀποδεικτικὴ ἢ διαλεκτική.
40 Συμβαίνει δ' ἐνίους ἀσυλλογίστως λέγειν διὰ τὸ λαμβάνειν
ἀμφοτέροις τὰ ἑπόμενα, οἷον καὶ ὁ Καινεὺς ποιεῖ,
1Hence it is clear that not every question will be relevant to geometry, nor to medicine, nor to any other science: only those questions will be geometrical which form premisses for the proof of the theorems of geometry or of any other science, such as optics, which uses the same basic truths as geometry. Of the other sciences the like is true. Of these questions the geometer is bound to give his account, using the basic truths of geometry in conjunction with his previous conclusions; 5of the basic truths the geometer, as such, is not bound to give any account. The like is true of the other sciences. There is a limit, then, to the questions which we may put to each man of science; nor is each man of science bound to answer all inquiries on each several subject, but only such as fall within the defined field of his own science. If, then, in controversy with a geometer qua geometer the disputant confines himself to geometry and proves anything from geometrical premisses, 10he is clearly to be applauded; if he goes outside these he will be at fault, and obviously cannot even refute the geometer except accidentally. One should therefore not discuss geometry among those who are not geometers, for in such a company an unsound argument will pass unnoticed. 15This is correspondingly true in the other sciences.
Since there are 'geometrical' questions, does it follow that there are also distinctively 'ungeometrical' questions? Further, in each special science-geometry for instance-what kind of error is it that may vitiate questions, and yet not exclude them from that science? Again, is the erroneous conclusion one constructed from premisses opposite to the true premisses, 20or is it formal fallacy though drawn from geometrical premisses? Or, perhaps, the erroneous conclusion is due to the drawing of premisses from another science; e.g. in a geometrical controversy a musical question is distinctively ungeometrical, whereas the notion that parallels meet is in one sense geometrical, being ungeometrical in a different fashion: the reason being that 'ungeometrical', like 'unrhythmical', is equivocal, 25meaning in the one case not geometry at all, in the other bad geometry? It is this error, i.e. error based on premisses of this kind-'of' the science but false-that is the contrary of science. In mathematics the formal fallacy is not so common, because it is the middle term in which the ambiguity lies, 30since the major is predicated of the whole of the middle and the middle of the whole of the minor (the predicate of course never has the prefix 'all'); and in mathematics one can, so to speak, see these middle terms with an intellectual vision, while in dialectic the ambiguity may escape detection. E.g. 'Is every circle a figure?' A diagram shows that this is so, but the minor premiss 'Are epics circles?' is shown by the diagram to be false.
If a proof has an 35inductive minor premiss, one should not bring an 'objection' against it. 40For since every premiss must be applicable to a number of cases (otherwise it will not be true in every instance, which, since the syllogism proceeds from universals, it must be), then assuredly the same is true of an 'objection'; since premisses and 'objections' are so far the same that anything which can be validly advanced as an 'objection' must be such that it could take the form of a premiss, either demonstrative or dialectical.
Since there are 'geometrical' questions, does it follow that there are also distinctively 'ungeometrical' questions? Further, in each special science-geometry for instance-what kind of error is it that may vitiate questions, and yet not exclude them from that science? Again, is the erroneous conclusion one constructed from premisses opposite to the true premisses, 20or is it formal fallacy though drawn from geometrical premisses? Or, perhaps, the erroneous conclusion is due to the drawing of premisses from another science; e.g. in a geometrical controversy a musical question is distinctively ungeometrical, whereas the notion that parallels meet is in one sense geometrical, being ungeometrical in a different fashion: the reason being that 'ungeometrical', like 'unrhythmical', is equivocal, 25meaning in the one case not geometry at all, in the other bad geometry? It is this error, i.e. error based on premisses of this kind-'of' the science but false-that is the contrary of science. In mathematics the formal fallacy is not so common, because it is the middle term in which the ambiguity lies, 30since the major is predicated of the whole of the middle and the middle of the whole of the minor (the predicate of course never has the prefix 'all'); and in mathematics one can, so to speak, see these middle terms with an intellectual vision, while in dialectic the ambiguity may escape detection. E.g. 'Is every circle a figure?' A diagram shows that this is so, but the minor premiss 'Are epics circles?' is shown by the diagram to be false.
If a proof has an 35inductive minor premiss, one should not bring an 'objection' against it. 40For since every premiss must be applicable to a number of cases (otherwise it will not be true in every instance, which, since the syllogism proceeds from universals, it must be), then assuredly the same is true of an 'objection'; since premisses and 'objections' are so far the same that anything which can be validly advanced as an 'objection' must be such that it could take the form of a premiss, either demonstrative or dialectical.
78a
1 ὅτι τὸ πῦρ ἐν τῇ πολλαπλασίᾳ ἀναλογίᾳ· καὶ γὰρ τὸ πῦρ
ταχὺ γεννᾶται, ὥς φησι, καὶ αὕτη ἡ ἀναλογία. οὕτω δ'
οὐκ ἔστι συλλογισμός· ἀλλ' εἰ τῇ ταχίστῃ ἀναλογίᾳ ἕπεται
ἡ πολλαπλάσιος καὶ τῷ πυρὶ ἡ ταχίστη ἐν τῇ κινήσει
5 ἀναλογία. ἐνίοτε μὲν οὖν οὐκ ἐνδέχεται συλλογίσασθαι ἐκ τῶν
εἰλημμένων, ὁτὲ δ' ἐνδέχεται, ἀλλ' οὐχ ὁρᾶται. Εἰ δ' ἦν
ἀδύνατον ἐκ ψεύδους ἀληθὲς δεῖξαι, ῥᾴδιον ἂν ἦν τὸ ἀναλύειν·
ἀντέστρεφε γὰρ ἂν ἐξ ἀνάγκης. ἔστω γὰρ τὸ Α ὄν·
τούτου δ' ὄντος ταδὶ ἔστιν, ἃ οἶδα ὅτι ἔστιν, οἷον τὸ Β. ἐκ
10 τούτων ἄρα δείξω ὅτι ἔστιν ἐκεῖνο. ἀντιστρέφει δὲ μᾶλλον
τὰ ἐν τοῖς μαθήμασιν, ὅτι οὐδὲν συμβεβηκὸς λαμβάνουσιν
(ἀλλὰ καὶ τούτῳ διαφέρουσι τῶν ἐν τοῖς διαλόγοις) ἀλλ'
ὁρισμούς.
Αὔξεται δ' οὐ διὰ τῶν μέσων, ἀλλὰ τῷ προσλαμβάνειν,
15 οἷον τὸ Α τοῦ Β, τοῦτο δὲ τοῦ Γ, πάλιν τοῦτο τοῦ Δ,
καὶ τοῦτ' εἰς ἄπειρον· καὶ εἰς τὸ πλάγιον, οἷον τὸ Α καὶ
κατὰ τοῦ Γ καὶ κατὰ τοῦ Ε, οἷον ἔστιν ἀριθμὸς ποσὸς ἢ
καὶ ἄπειρος τοῦτο ἐφ' ᾧ Α, ὁ περιττὸς ἀριθμὸς ποσὸς ἐφ'
οὗ Β, ἀριθμὸς περιττὸς ἐφ' οὗ Γ· ἔστιν ἄρα τὸ Α κατὰ
20 τοῦ Γ. καὶ ἔστιν ὁ ἄρτιος ποσὸς ἀριθμὸς ἐφ' οὗ Δ, ὁ ἄρτιος
ἀριθμὸς ἐφ' οὗ Ε· ἔστιν ἄρα τὸ Α κατὰ τοῦ Ε.
1On the other hand, arguments formally illogical do sometimes occur through taking as middles mere attributes of the major and minor terms. An instance of this is Caeneus' proof that fire increases in geometrical proportion: 'Fire', he argues, 'increases rapidly, and so does geometrical proportion'. There is no syllogism so, but there is a syllogism if the most rapidly increasing proportion is geometrical and the most rapidly increasing proportion is attributable to fire in its motion. 5Sometimes, no doubt, it is impossible to reason from premisses predicating mere attributes: but sometimes it is possible, though the possibility is overlooked. If false premisses could never give true conclusions 'resolution' would be easy, for premisses and conclusion would in that case inevitably reciprocate. I might then argue thus: let A be an existing fact; let the existence of A imply such and such facts actually known to me to exist, which we may call B. 10I can now, since they reciprocate, infer A from B.
Reciprocation of premisses and conclusion is more frequent in mathematics, because mathematics takes definitions, but never an accident, for its premisses-a second characteristic distinguishing mathematical reasoning from dialectical disputations.
A science expands not by the interposition of fresh middle terms, but by the apposition of fresh extreme terms. E.g. 15A is predicated of B, B of C, C of D, and so indefinitely. Or the expansion may be lateral: e.g. one major A, may be proved of two minors, C and E. Thus let A represent number-a number or number taken indeterminately; B determinate odd number; C any particular odd number. We can then predicate A of C. 20Next let D represent determinate even number, and E even number. Then A is predicable of E.
Reciprocation of premisses and conclusion is more frequent in mathematics, because mathematics takes definitions, but never an accident, for its premisses-a second characteristic distinguishing mathematical reasoning from dialectical disputations.
A science expands not by the interposition of fresh middle terms, but by the apposition of fresh extreme terms. E.g. 15A is predicated of B, B of C, C of D, and so indefinitely. Or the expansion may be lateral: e.g. one major A, may be proved of two minors, C and E. Thus let A represent number-a number or number taken indeterminately; B determinate odd number; C any particular odd number. We can then predicate A of C. 20Next let D represent determinate even number, and E even number. Then A is predicable of E.
Book 1,Chapter 13 (78a22–79a16)
Τὸ δ' ὅτι διαφέρει καὶ τὸ διότι ἐπίστασθαι, πρῶτον
μὲν ἐν τῇ αὐτῇ ἐπιστήμῃ, καὶ ἐν ταύτῃ διχῶς, ἕνα μὲν
τρόπον ἐὰν μὴ δι' ἀμέσων γίνηται ὁ συλλογισμός (οὐ γὰρ
25 λαμβάνεται τὸ πρῶτον αἴτιον, ἡ δὲ τοῦ διότι ἐπιστήμη κατὰ
τὸ πρῶτον αἴτιον), ἄλλον δὲ εἰ δι' ἀμέσων μέν, ἀλλὰ
μὴ διὰ τοῦ αἰτίου ἀλλὰ τῶν ἀντιστρεφόντων διὰ τοῦ γνωριμωτέρου.
κωλύει γὰρ οὐδὲν τῶν ἀντικατηγορουμένων γνωριμώτερον
εἶναι ἐνίοτε τὸ μὴ αἴτιον, ὥστ' ἔσται διὰ τούτου ἡ
30 ἀπόδειξις, οἷον ὅτι ἐγγὺς οἱ πλάνητες διὰ τοῦ μὴ στίλβειν.
ἔστω ἐφ' ᾧ Γ πλάνητες, ἐφ' ᾧ Β τὸ μὴ στίλβειν, ἐφ' ᾧ
Α τὸ ἐγγὺς εἶναι. ἀληθὲς δὴ τὸ Β κατὰ τοῦ Γ εἰπεῖν· οἱ
γὰρ πλάνητες οὐ στίλβουσιν. ἀλλὰ καὶ τὸ Α κατὰ τοῦ Β· τὸ
γὰρ μὴ στίλβον ἐγγύς ἐστι· τοῦτο δ' εἰλήφθω δι' ἐπαγωγῆς
35 ἢ δι' αἰσθήσεως. ἀνάγκη οὖν τὸ Α τῷ Γ ὑπάρχειν, ὥστ'
ἀποδέδεικται ὅτι οἱ πλάνητες ἐγγύς εἰσιν. οὗτος οὖν ὁ συλλογισμὸς
οὐ τοῦ διότι ἀλλὰ τοῦ ὅτι ἐστίν· οὐ γὰρ διὰ τὸ μὴ
στίλβειν ἐγγύς εἰσιν, ἀλλὰ διὰ τὸ ἐγγὺς εἶναι οὐ στίλβουσιν.
ἐγχωρεῖ δὲ καὶ διὰ θατέρου θάτερον δειχθῆναι, καὶ ἔσται
40 τοῦ διότι ἡ ἀπόδειξις, οἷον ἔστω τὸ Γ πλάνητες, ἐφ' ᾧ Β
22Knowledge of the fact differs from knowledge of the reasoned fact. To begin with, they differ within the same science and in two ways: (1) when the premisses of the syllogism are not immediate 25(for then the proximate cause is not contained in them-a necessary condition of knowledge of the reasoned fact): (2) when the premisses are immediate, but instead of the cause the better known of the two reciprocals is taken as the middle; for of two reciprocally predicable terms the one which is not the cause may quite easily be the better known and so become the middle term of the demonstration. 30Thus (2, a) you might prove as follows that the planets are near because they do not twinkle: let C be the planets, B not twinkling, A proximity. Then B is predicable of C; for the planets do not twinkle. But A is also predicable of B, since that which does not twinkle is near--we must take this truth as having been reached by induction 35or sense-perception. Therefore A is a necessary predicate of C; so that we have demonstrated that the planets are near. This syllogism, then, proves not the reasoned fact but only the fact; since they are not near because they do not twinkle, but, because they are near, do not twinkle. The major and middle of the proof, however, may be reversed, and then 40the demonstration will be of the reasoned fact. Thus: let C be the planets, B proximity, A not twinkling.
78b
1 τὸ ἐγγὺς εἶναι, τὸ Α τὸ μὴ στίλβειν· ὑπάρχει δὴ καὶ τὸ
Β τῷ Γ καὶ τὸ Α τῷ Β, ὥστε καὶ τῷ Γ τὸ Α [τὸ μὴ στίλβειν].
καὶ ἔστι τοῦ διότι ὁ συλλογισμός· εἴληπται γὰρ τὸ
πρῶτον αἴτιον. πάλιν ὡς τὴν σελήνην δεικνύουσιν ὅτι σφαιροειδής,
5 διὰ τῶν αὐξήσεων—εἰ γὰρ τὸ αὐξανόμενον οὕτω
σφαιροειδές, αὐξάνει δ' ἡ σελήνη, φανερὸν ὅτι σφαιροειδής—οὕτω
μὲν οὖν τοῦ ὅτι γέγονεν ὁ συλλογισμός, ἀνάπαλιν
δὲ τεθέντος τοῦ μέσου τοῦ διότι· οὐ γὰρ διὰ τὰς αὐξήσεις
σφαιροειδής ἐστιν, ἀλλὰ διὰ τὸ σφαιροειδὴς εἶναι λαμβάνει
10 τὰς αὐξήσεις τοιαύτας. σελήνη ἐφ' ᾧ Γ, σφαιροειδὴς
ἐφ' ᾧ Β, αὔξησις ἐφ' ᾧ Α. ἐφ' ὧν δὲ τὰ μέσα μὴ
ἀντιστρέφει καὶ ἔστι γνωριμώτερον τὸ ἀναίτιον, τὸ ὅτι μὲν
δείκνυται, τὸ διότι δ' οὔ. Ἔτι ἐφ' ὧν τὸ μέσον ἔξω τίθεται.
καὶ γὰρ ἐν τούτοις τοῦ ὅτι καὶ οὐ τοῦ διότι ἡ ἀπόδειξις· οὐ
15 γὰρ λέγεται τὸ αἴτιον. οἷον διὰ τί οὐκ ἀναπνεῖ ὁ τοῖχος;
ὅτι οὐ ζῷον. εἰ γὰρ τοῦτο τοῦ μὴ ἀναπνεῖν αἴτιον, ἔδει τὸ
ζῷον εἶναι αἴτιον τοῦ ἀναπνεῖν, οἷον εἰ ἡ ἀπόφασις αἰτία τοῦ
μὴ ὑπάρχειν, ἡ κατάφασις τοῦ ὑπάρχειν, ὥσπερ εἰ τὸ ἀσύμμετρα
εἶναι τὰ θερμὰ καὶ τὰ ψυχρὰ τοῦ μὴ ὑγιαίνειν, τὸ
20 σύμμετρα εἶναι τοῦ ὑγιαίνειν, —ὁμοίως δὲ καὶ εἰ ἡ κατάφασις
τοῦ ὑπάρχειν, ἡ ἀπόφασις τοῦ μὴ ὑπάρχειν. ἐπὶ δὲ
τῶν οὕτως ἀποδεδομένων οὐ συμβαίνει τὸ λεχθέν· οὐ γὰρ
ἅπαν ἀναπνεῖ ζῷον. ὁ δὲ συλλογισμὸς γίνεται τῆς τοιαύτης
αἰτίας ἐν τῷ μέσῳ σχήματι. οἷον ἔστω τὸ Α ζῷον, ἐφ'
25 ᾧ Β τὸ ἀναπνεῖν, ἐφ' ᾧ Γ τοῖχος. τῷ μὲν οὖν Β παντὶ
ὑπάρχει τὸ Α (πᾶν γὰρ τὸ ἀναπνέον ζῷον), τῷ δὲ Γ οὐθενί,
ὥστε οὐδὲ τὸ Β τῷ Γ οὐθενί· οὐκ ἄρα ἀναπνεῖ ὁ τοῖχος.
ἐοίκασι δ' αἱ τοιαῦται τῶν αἰτιῶν τοῖς καθ' ὑπερβολὴν
εἰρημένοις· τοῦτο δ' ἔστι τὸ πλέον ἀποστήσαντα τὸ μέσον
30 εἰπεῖν, οἷον τὸ τοῦ Ἀναχάρσιος, ὅτι ἐν Σκύθαις οὐκ εἰσὶν
αὐλητρίδες, οὐδὲ γὰρ ἄμπελοι.
Κατὰ μὲν δὴ τὴν αὐτὴν ἐπιστήμην καὶ κατὰ τὴν τῶν
μέσων θέσιν αὗται διαφοραί εἰσι τοῦ ὅτι πρὸς τὸν τοῦ διότι
συλλογισμόν· ἄλλον δὲ τρόπον διαφέρει τὸ διότι τοῦ ὅτι
35 τῷ δι' ἄλλης ἐπιστήμης ἑκάτερον θεωρεῖν. τοιαῦτα δ' ἐστὶν
ὅσα οὕτως ἔχει πρὸς ἄλληλα ὥστ' εἶναι θάτερον ὑπὸ θάτερον,
οἷον τὰ ὀπτικὰ πρὸς γεωμετρίαν καὶ τὰ μηχανικὰ
πρὸς στερεομετρίαν καὶ τὰ ἁρμονικὰ πρὸς ἀριθμητικὴν καὶ
τὰ φαινόμενα πρὸς ἀστρολογικήν. σχεδὸν δὲ συνώνυμοί εἰσιν
40 ἔνιαι τούτων τῶν ἐπιστημῶν, οἷον ἀστρολογία ἥ τε μαθηματικὴ
1Then B is an attribute of C, and A-not twinkling-of B. Consequently A is predicable of C, and the syllogism proves the reasoned fact, since its middle term is the proximate cause. Another example is the inference that the moon is spherical 5from its manner of waxing. Thus: since that which so waxes is spherical, and since the moon so waxes, clearly the moon is spherical. Put in this form, the syllogism turns out to be proof of the fact, but if the middle and major be reversed it is proof of the reasoned fact; since the moon is not spherical because it waxes in a certain manner, 10but waxes in such a manner because it is spherical. (Let C be the moon, B spherical, and A waxing.) Again (b), in cases where the cause and the effect are not reciprocal and the effect is the better known, the fact is demonstrated but not the reasoned fact. This also occurs (1) when the middle falls outside the major and minor, for here too 15the strict cause is not given, and so the demonstration is of the fact, not of the reasoned fact. For example, the question 'Why does not a wall breathe?' might be answered, 'Because it is not an animal'; but that answer would not give the strict cause, because if not being an animal causes the absence of respiration, then being an animal should be the cause of respiration, according to the rule that if the negation of causes the non-inherence of y, the affirmation of x causes the inherence of y; e.g. if the disproportion of the hot and cold elements is the cause of ill health, 20their proportion is the cause of health; and conversely, if the assertion of x causes the inherence of y, the negation of x must cause y's non-inherence. But in the case given this consequence does not result; for not every animal breathes. A syllogism with this kind of cause takes place in the second figure. Thus: let A be animal, 25B respiration, C wall. Then A is predicable of all B (for all that breathes is animal), but of no C; and consequently B is predicable of no C; that is, the wall does not breathe. Such causes are like far-fetched explanations, which precisely consist in making the cause too remote, 30as in Anacharsis' account of why the Scythians have no flute-players; namely because they have no vines.
Thus, then, do the syllogism of the fact and the syllogism of the reasoned fact differ within one science and according to the position of the middle terms. But there is another way too in which the fact and the reasoned fact differ, and that is 35when they are investigated respectively by different sciences. This occurs in the case of problems related to one another as subordinate and superior, as when optical problems are subordinated to geometry, mechanical problems to stereometry, harmonic problems to arithmetic, the data of observation to astronomy. (40Some of these sciences bear almost the same name; e.g. mathematical and nautical astronomy, mathematical and acoustical harmonics.)
Thus, then, do the syllogism of the fact and the syllogism of the reasoned fact differ within one science and according to the position of the middle terms. But there is another way too in which the fact and the reasoned fact differ, and that is 35when they are investigated respectively by different sciences. This occurs in the case of problems related to one another as subordinate and superior, as when optical problems are subordinated to geometry, mechanical problems to stereometry, harmonic problems to arithmetic, the data of observation to astronomy. (40Some of these sciences bear almost the same name; e.g. mathematical and nautical astronomy, mathematical and acoustical harmonics.)
79a
1 καὶ ἡ ναυτική, καὶ ἁρμονικὴ ἥ τε μαθηματικὴ
καὶ ἡ κατὰ τὴν ἀκοήν. ἐνταῦθα γὰρ τὸ μὲν ὅτι τῶν αἰσθητικῶν
εἰδέναι, τὸ δὲ διότι τῶν μαθηματικῶν· οὗτοι γὰρ ἔχουσι
τῶν αἰτίων τὰς ἀποδείξεις, καὶ πολλάκις οὐκ ἴσασι τὸ ὅτι, καθάπερ
5 οἱ τὸ καθόλου θεωροῦντες πολλάκις ἔνια τῶν καθ' ἕκαστον
οὐκ ἴσασι δι' ἀνεπισκεψίαν. ἔστι δὲ ταῦτα ὅσα ἕτερόν τι ὄντα
τὴν οὐσίαν κέχρηται τοῖς εἴδεσιν. τὰ γὰρ μαθήματα περὶ εἴδη
ἐστίν· οὐ γὰρ καθ' ὑποκειμένου τινός· εἰ γὰρ καὶ καθ' ὑποκειμένου
τινὸς τὰ γεωμετρικά ἐστιν, ἀλλ' οὐχ ᾗ γε καθ' ὑποκειμένου.
10 ἔχει δὲ καὶ πρὸς τὴν ὀπτικήν, ὡς αὕτη πρὸς τὴν γεωμετρίαν,
ἄλλη πρὸς ταύτην, οἷον τὸ περὶ τῆς ἴριδος· τὸ μὲν
γὰρ ὅτι φυσικοῦ εἰδέναι, τὸ δὲ διότι ὀπτικοῦ, ἢ ἁπλῶς ἢ τοῦ
κατὰ τὸ μάθημα. πολλαὶ δὲ καὶ τῶν μὴ ὑπ' ἀλλήλας
ἐπιστημῶν ἔχουσιν οὕτως, οἷον ἰατρικὴ πρὸς γεωμετρίαν· ὅτι
15 μὲν γὰρ τὰ ἕλκη τὰ περιφερῆ βραδύτερον ὑγιάζεται, τοῦ
ἰατροῦ εἰδέναι, διότι δὲ τοῦ γεωμέτρου.
1Here it is the business of the empirical observers to know the fact, of the mathematicians to know the reasoned fact; for the latter are in possession of the demonstrations giving the causes, and are often ignorant of the fact: just as 5we have often a clear insight into a universal, but through lack of observation are ignorant of some of its particular instances. These connexions have a perceptible existence though they are manifestations of forms. For the mathematical sciences concern forms: they do not demonstrate properties of a substratum, since, even though the geometrical subjects are predicable as properties of a perceptible substratum, it is not as thus predicable that the mathematician demonstrates properties of them. 10As optics is related to geometry, so another science is related to optics, namely the theory of the rainbow. Here knowledge of the fact is within the province of the natural philosopher, knowledge of the reasoned fact within that of the optician, either qua optician or qua mathematical optician. Many sciences not standing in this mutual relation enter into it at points; e.g. medicine and geometry: it is the physician's business to know 15that circular wounds heal more slowly, the geometer's to know the reason why.
Book 1,Chapter 14 (79a17–32)
Τῶν δὲ σχημάτων ἐπιστημονικὸν μάλιστα τὸ πρῶτόν
ἐστιν. αἵ τε γὰρ μαθηματικαὶ τῶν ἐπιστημῶν διὰ τούτου
φέρουσι τὰς ἀποδείξεις, οἷον ἀριθμητικὴ καὶ γεωμετρία καὶ
20 ὀπτική, καὶ σχεδὸν ὡς εἰπεῖν ὅσαι τοῦ διότι ποιοῦνται τὴν
σκέψιν· ἢ γὰρ ὅλως ἢ ὡς ἐπὶ τὸ πολὺ καὶ ἐν τοῖς πλείστοις
διὰ τούτου τοῦ σχήματος ὁ τοῦ διότι συλλογισμός. ὥστε
κἂν διὰ τοῦτ' εἴη μάλιστα ἐπιστημονικόν· κυριώτατον γὰρ
τοῦ εἰδέναι τὸ διότι θεωρεῖν. εἶτα τὴν τοῦ τί ἐστιν ἐπιστήμην
25 διὰ μόνου τούτου θηρεῦσαι δυνατόν. ἐν μὲν γὰρ τῷ μέσῳ
σχήματι οὐ γίνεται κατηγορικὸς συλλογισμός, ἡ δὲ τοῦ
τί ἐστιν ἐπιστήμη καταφάσεως· ἐν δὲ τῷ ἐσχάτῳ γίνεται
μὲν ἀλλ' οὐ καθόλου, τὸ δὲ τί ἐστι τῶν καθόλου ἐστίν· οὐ
γὰρ πῇ ἐστι ζῷον δίπουν ὁ ἄνθρωπος. ἔτι τοῦτο μὲν ἐκείνων
30 οὐδὲν προσδεῖται, ἐκεῖνα δὲ διὰ τούτου καταπυκνοῦται καὶ
αὔξεται, ἕως ἂν εἰς τὰ ἄμεσα ἔλθῃ. φανερὸν οὖν ὅτι κυριώτατον
τοῦ ἐπίστασθαι τὸ πρῶτον σχῆμα.
17Of all the figures the most scientific is the first. Thus, it is the vehicle of the demonstrations of all the mathematical sciences, such as arithmetic, geometry, and 20optics, and practically all of all sciences that investigate causes: for the syllogism of the reasoned fact is either exclusively or generally speaking and in most cases in this figure-a second proof that this figure is the most scientific; for grasp of a reasoned conclusion is the primary condition of knowledge. Thirdly, the first is 25the only figure which enables us to pursue knowledge of the essence of a thing. In the second figure no affirmative conclusion is possible, and knowledge of a thing's essence must be affirmative; while in the third figure the conclusion can be affirmative, but cannot be universal, and essence must have a universal character: e.g. man is not two-footed animal in any qualified sense, but universally. Finally, the first figure 30has no need of the others, while it is by means of the first that the other two figures are developed, and have their intervals closepacked until immediate premisses are reached.
Clearly, therefore, the first figure is the primary condition of knowledge.
Clearly, therefore, the first figure is the primary condition of knowledge.
Book 1,Chapter 15 (79a33–79b22)
Ὥσπερ δὲ ὑπάρχειν τὸ Α τῷ Β ἐνεδέχετο ἀτόμως, οὕτω
καὶ μὴ ὑπάρχειν ἐγχωρεῖ. λέγω δὲ τὸ ἀτόμως ὑπάρχειν ἢ
35 μὴ ὑπάρχειν τὸ μὴ εἶναι αὐτῶν μέσον· οὕτω γὰρ οὐκέτι ἔσται
κατ' ἄλλο τὸ ὑπάρχειν ἢ μὴ ὑπάρχειν. ὅταν μὲν οὖν ἢ τὸ Α
ἢ τὸ Β ἐν ὅλῳ τινὶ ᾖ, ἢ καὶ ἄμφω, οὐκ ἐνδέχεται τὸ Α τῷ
Β πρώτως μὴ ὑπάρχειν. ἔστω γὰρ τὸ Α ἐν ὅλῳ τῷ Γ.
οὐκοῦν εἰ τὸ Β μὴ ἔστιν ἐν ὅλῳ τῷ Γ (ἐγχωρεῖ γὰρ τὸ μὲν
40 Α εἶναι ἔν τινι ὅλῳ, τὸ δὲ Β μὴ εἶναι ἐν τούτῳ), συλλογισμὸς
ἔσται τοῦ μὴ ὑπάρχειν τὸ Α τῷ Β· εἰ γὰρ τῷ μὲν
33Just as an attribute A may (as we saw) be atomically connected with a subject B, so its disconnexion may be atomic. I call 'atomic' connexions or disconnexions 35which involve no intermediate term; since in that case the connexion or disconnexion will not be mediated by something other than the terms themselves. It follows that if either A or B, or both A and B, have a genus, their disconnexion cannot be primary. Thus: let C be the genus of A. Then, if C is not the genus of B-40for A may well have a genus which is not the genus of B-there will be a syllogism proving A's disconnexion from B thus:
all A is C, no B is C, therefore no B is A.
all A is C, no B is C, therefore no B is A.
79b
1 Α παντὶ τὸ Γ, τῷ δὲ Β μηδενί, οὐδενὶ τῷ Β τὸ Α. ὁμοίως
δὲ καὶ εἰ τὸ Β ἐν ὅλῳ τινί ἐστιν, οἷον ἐν τῷ Δ· τὸ μὲν
γὰρ Δ παντὶ τῷ Β ὑπάρχει, τὸ δὲ Α οὐδενὶ τῷ Δ, ὥστε
τὸ Α οὐδενὶ τῷ Β ὑπάρξει διὰ συλλογισμοῦ. τὸν αὐτὸν
5 δὲ τρόπον δειχθήσεται καὶ εἰ ἄμφω ἐν ὅλῳ τινί ἐστιν. ὅτι
δ' ἐνδέχεται τὸ Β μὴ εἶναι ἐν ᾧ ὅλῳ ἐστὶ τὸ Α, ἢ πάλιν
τὸ Α ἐν ᾧ τὸ Β, φανερὸν ἐκ τῶν συστοιχιῶν, ὅσαι μὴ ἐπαλλάττουσιν
ἀλλήλαις. εἰ γὰρ μηδὲν τῶν ἐν τῇ Α Γ Δ συστοιχίᾳ
κατὰ μηδενὸς κατηγορεῖται τῶν ἐν τῇ Β Ε Ζ, τὸ
10 δ' Α ἐν ὅλῳ ἐστὶ τῷ Θ συστοίχῳ ὄντι, φανερὸν ὅτι τὸ Β
οὐκ ἔσται ἐν τῷ Θ· ἐπαλλάξουσι γὰρ αἱ συστοιχίαι. ὁμοίως
δὲ καὶ εἰ τὸ Β ἐν ὅλῳ τινί ἐστιν. ἐὰν δὲ μηδέτερον ᾖ ἐν
ὅλῳ μηδενί, μὴ ὑπάρχῃ δὲ τὸ Α τῷ Β, ἀνάγκη ἀτόμως
μὴ ὑπάρχειν. εἰ γὰρ ἔσται τι μέσον, ἀνάγκη θάτερον αὐτῶν
15 ἐν ὅλῳ τινὶ εἶναι. ἢ γὰρ ἐν τῷ πρώτῳ σχήματι ἢ ἐν
τῷ μέσῳ ἔσται ὁ συλλογισμός. εἰ μὲν οὖν ἐν τῷ πρώτῳ,
τὸ Β ἔσται ἐν ὅλῳ τινί (καταφατικὴν γὰρ δεῖ τὴν πρὸς τοῦτο
γενέσθαι πρότασιν), εἰ δ' ἐν τῷ μέσῳ, ὁπότερον ἔτυχεν
(πρὸς ἀμφοτέροις γὰρ ληφθέντος τοῦ στερητικοῦ γίνεται συλλογισμός·
20 ἀμφοτέρων δ' ἀποφατικῶν οὐσῶν οὐκ ἔσται).
Φανερὸν οὖν ὅτι ἐνδέχεταί τε ἄλλο ἄλλῳ μὴ ὑπάρχειν ἀτόμως,
καὶ πότ' ἐνδέχεται καὶ πῶς, εἰρήκαμεν.
1Or if it is B which has a genus D, we have all B is D, no D is A, therefore no B is A, by syllogism; 5and the proof will be similar if both A and B have a genus. That the genus of A need not be the genus of B and vice versa, is shown by the existence of mutually exclusive coordinate series of predication. If no term in the series ACD...is predicable of any term in the series BEF...10,and if G-a term in the former series-is the genus of A, clearly G will not be the genus of B; since, if it were, the series would not be mutually exclusive. So also if B has a genus, it will not be the genus of A. If, on the other hand, neither A nor B has a genus and A does not inhere in B, this disconnexion must be atomic. If there be a middle term, one or other of them 15is bound to have a genus, for the syllogism will be either in the first or the second figure. If it is in the first, B will have a genus-for the premiss containing it must be affirmative: if in the second, either A or B indifferently, since syllogism is possible if either is contained in a negative premiss, 20but not if both premisses are negative.
Hence it is clear that one thing may be atomically disconnected from another, and we have stated when and how this is possible.
Hence it is clear that one thing may be atomically disconnected from another, and we have stated when and how this is possible.
Book 1,Chapter 16 (79b23–80b16)
Ἄγνοια δ' ἡ μὴ κατ' ἀπόφασιν ἀλλὰ κατὰ διάθεσιν
λεγομένη ἔστι μὲν ἡ διὰ συλλογισμοῦ γινομένη ἀπάτη,
25 αὕτη δ' ἐν μὲν τοῖς πρώτως ὑπάρχουσιν ἢ μὴ ὑπάρχουσι
συμβαίνει διχῶς· ἢ γὰρ ὅταν ἁπλῶς ὑπολάβῃ ὑπάρχειν
ἢ μὴ ὑπάρχειν, ἢ ὅταν διὰ συλλογισμοῦ λάβῃ τὴν ὑπόληψιν.
τῆς μὲν οὖν ἁπλῆς ὑπολήψεως ἁπλῆ ἡ ἀπάτη, τῆς
δὲ διὰ συλλογισμοῦ πλείους. μὴ ὑπαρχέτω γὰρ τὸ Α μηδενὶ
30 τῷ Β ἀτόμως· οὐκοῦν ἐὰν συλλογίζηται ὑπάρχειν τὸ
Α τῷ Β, μέσον λαβὼν τὸ Γ, ἠπατημένος ἔσται διὰ συλλογισμοῦ.
ἐνδέχεται μὲν οὖν ἀμφοτέρας τὰς προτάσεις εἶναι
ψευδεῖς, ἐνδέχεται δὲ τὴν ἑτέραν μόνον. εἰ γὰρ μήτε
τὸ Α μηδενὶ τῶν Γ ὑπάρχει μήτε τὸ Γ μηδενὶ τῶν Β, εἴληπται
35 δ' ἑκατέρα ἀνάπαλιν, ἄμφω ψευδεῖς ἔσονται. ἐγχωρεῖ
δ' οὕτως ἔχειν τὸ Γ πρὸς τὸ Α καὶ Β ὥστε μήτε ὑπὸ
τὸ Α εἶναι μήτε καθόλου τῷ Β. τὸ μὲν γὰρ Β ἀδύνατον
εἶναι ἐν ὅλῳ τινί (πρώτως γὰρ ἐλέγετο αὐτῷ τὸ Α μὴ ὑπάρχειν),
τὸ δὲ Α οὐκ ἀνάγκη πᾶσι τοῖς οὖσιν εἶναι καθόλου,
40 ὥστ' ἀμφότεραι ψευδεῖς. ἀλλὰ καὶ τὴν ἑτέραν ἐνδέχεται
ἀληθῆ λαμβάνειν, οὐ μέντοι ὁποτέραν ἔτυχεν, ἀλλὰ τὴν
23Ignorance-defined not as the negation of knowledge but as a positive state of mind-is error produced by inference.
25(1) Let us first consider propositions asserting a predicate's immediate connexion with or disconnexion from a subject. Here, it is true, positive error may befall one in alternative ways; for it may arise where one directly believes a connexion or disconnexion as well as where one's belief is acquired by inference. The error, however, that consists in a direct belief is without complication; but the error resulting from inference-which here concerns us-takes many forms. 30Thus, let A be atomically disconnected from all B: then the conclusion inferred through a middle term C, that all B is A, will be a case of error produced by syllogism. Now, two cases are possible. Either (a) both premisses, or (b) one premiss only, may be false. (a) If neither A is an attribute of any C nor C of any B, 35whereas the contrary was posited in both cases, both premisses will be false. (C may quite well be so related to A and B that C is neither subordinate to A nor a universal attribute of B: for B, since A was said to be primarily disconnected from B, cannot have a genus, and A need not necessarily be a universal attribute of all things. 40Consequently both premisses may be false.)
25(1) Let us first consider propositions asserting a predicate's immediate connexion with or disconnexion from a subject. Here, it is true, positive error may befall one in alternative ways; for it may arise where one directly believes a connexion or disconnexion as well as where one's belief is acquired by inference. The error, however, that consists in a direct belief is without complication; but the error resulting from inference-which here concerns us-takes many forms. 30Thus, let A be atomically disconnected from all B: then the conclusion inferred through a middle term C, that all B is A, will be a case of error produced by syllogism. Now, two cases are possible. Either (a) both premisses, or (b) one premiss only, may be false. (a) If neither A is an attribute of any C nor C of any B, 35whereas the contrary was posited in both cases, both premisses will be false. (C may quite well be so related to A and B that C is neither subordinate to A nor a universal attribute of B: for B, since A was said to be primarily disconnected from B, cannot have a genus, and A need not necessarily be a universal attribute of all things. 40Consequently both premisses may be false.)
80a
1 Α Γ· ἡ γὰρ Γ Β πρότασις ἀεὶ ψευδὴς ἔσται διὰ τὸ ἐν μηδενὶ
εἶναι τὸ Β, τὴν δὲ Α Γ ἐγχωρεῖ, οἷον εἰ τὸ Α καὶ τῷ
Γ καὶ τῷ Β ὑπάρχει ἀτόμως (ὅταν γὰρ πρώτως κατηγορῆται
ταὐτὸ πλειόνων, οὐδέτερον ἐν οὐδετέρῳ ἔσται). διαφέρει
5 δ' οὐδέν, οὐδ' εἰ μὴ ἀτόμως ὑπάρχει.
Ἡ μὲν οὖν τοῦ ὑπάρχειν ἀπάτη διὰ τούτων τε καὶ
οὕτω γίνεται μόνως (οὐ γὰρ ἦν ἐν ἄλλῳ σχήματι τοῦ ὑπάρχειν
συλλογισμός), ἡ δὲ τοῦ μὴ ὑπάρχειν ἔν τε τῷ πρώτῳ
καὶ ἐν τῷ μέσῳ σχήματι. πρῶτον οὖν εἴπωμεν ποσαχῶς
10 ἐν τῷ πρώτῳ γίνεται, καὶ πῶς ἐχουσῶν τῶν προτάσεων.
ἐνδέχεται μὲν οὖν ἀμφοτέρων ψευδῶν οὐσῶν, οἷον εἰ τὸ
Α καὶ τῷ Γ καὶ τῷ Β ὑπάρχει ἀτόμως· ἐὰν γὰρ ληφθῇ
τὸ μὲν Α τῷ Γ μηδενί, τὸ δὲ Γ παντὶ τῷ Β, ψευδεῖς
αἱ προτάσεις. ἐνδέχεται δὲ καὶ τῆς ἑτέρας ψευδοῦς οὔσης,
15 καὶ ταύτης ὁποτέρας ἔτυχεν. ἐγχωρεῖ γὰρ τὴν μὲν Α Γ
ἀληθῆ εἶναι, τὴν δὲ Γ Β ψευδῆ, τὴν μὲν Α Γ ἀληθῆ ὅτι
οὐ πᾶσι τοῖς οὖσιν ὑπάρχει τὸ Α, τὴν δὲ Γ Β ψευδῆ ὅτι
ἀδύνατον ὑπάρχειν τῷ Β τὸ Γ, ᾧ μηδενὶ ὑπάρχει τὸ Α·
οὐ γὰρ ἔτι ἀληθὴς ἔσται ἡ Α Γ πρότασις· ἅμα δέ, εἰ καὶ
20 εἰσὶν ἀμφότεραι ἀληθεῖς, καὶ τὸ συμπέρασμα ἔσται ἀληθές.
ἀλλὰ καὶ τὴν Γ Β ἐνδέχεται ἀληθῆ εἶναι τῆς ἑτέρας οὔσης
ψευδοῦς, οἷον εἰ τὸ Β καὶ ἐν τῷ Γ καὶ ἐν τῷ Α ἐστίν·
ἀνάγκη γὰρ θάτερον ὑπὸ θάτερον εἶναι, ὥστ' ἂν λάβῃ τὸ
Α μηδενὶ τῷ Γ ὑπάρχειν, ψευδὴς ἔσται ἡ πρότασις. φανερὸν
25 οὖν ὅτι καὶ τῆς ἑτέρας ψευδοῦς οὔσης καὶ ἀμφοῖν ἔσται
ψευδὴς ὁ συλλογισμός.
Ἐν δὲ τῷ μέσῳ σχήματι ὅλας μὲν εἶναι τὰς προτάσεις
ἀμφοτέρας ψευδεῖς οὐκ ἐνδέχεται· ὅταν γὰρ τὸ Α παντὶ τῷ
Β ὑπάρχῃ, οὐδὲν ἔσται λαβεῖν ὃ τῷ μὲν ἑτέρῳ παντὶ θατέρῳ
30 δ' οὐδενὶ ὑπάρξει· δεῖ δ' οὕτω λαμβάνειν τὰς προτάσεις
ὥστε τῷ μὲν ὑπάρχειν τῷ δὲ μὴ ὑπάρχειν, εἴπερ ἔσται συλλογισμός.
εἰ οὖν οὕτω λαμβανόμεναι ψευδεῖς, δῆλον ὡς ἐναντίως
ἀνάπαλιν ἕξουσι· τοῦτο δ' ἀδύνατον. ἐπί τι δ' ἑκατέραν
οὐδὲν κωλύει ψευδῆ εἶναι, οἷον εἰ τὸ Γ καὶ τῷ Α καὶ
35 τῷ Β τινὶ ὑπάρχοι· ἂν γὰρ τῷ μὲν Α παντὶ ληφθῇ ὑπάρχον,
τῷ δὲ Β μηδενί, ψευδεῖς μὲν ἀμφότεραι αἱ προτάσεις,
οὐ μέντοι ὅλαι ἀλλ' ἐπί τι. καὶ ἀνάπαλιν δὲ τεθέντος
τοῦ στερητικοῦ ὡσαύτως. τὴν δ' ἑτέραν εἶναι ψευδῆ καὶ
ὁποτερανοῦν ἐνδέχεται. ὃ γὰρ ὑπάρχει τῷ Α παντί, καὶ
40 τῷ Β ὑπάρχει· ἐὰν οὖν ληφθῇ τῷ μὲν Α ὅλῳ ὑπάρχειν
1On the other hand, (b) one of the premisses may be true, though not either indifferently but only the major A-C since, B having no genus, the premiss C-B will always be false, while A-C may be true. This is the case if, for example, A is related atomically to both C and B; because when the same term is related atomically to more terms than one, neither of those terms will belong to the other. 5It is, of course, equally the case if A-C is not atomic.
Error of attribution, then, occurs through these causes and in this form only-for we found that no syllogism of universal attribution was possible in any figure but the first. On the other hand, an error of non-attribution may occur either in the first or in the second figure. Let us therefore first explain the various forms it takes 10in the first figure and the character of the premisses in each case.
(c) It may occur when both premisses are false; e.g. supposing A atomically connected with both C and B, if it be then assumed that no C is and all B is C, both premisses are false.
(d) It is also possible when one is false. 15This may be either premiss indifferently. A-C may be true, C-B false-A-C true because A is not an attribute of all things, C-B false because C, which never has the attribute A, cannot be an attribute of B; for if C-B were true, the premiss A-C would no longer be true, and besides 20if both premisses were true, the conclusion would be true. Or again, C-B may be true and A-C false; e.g. if both C and A contain B as genera, one of them must be subordinate to the other, so that if the premiss takes the form No C is A, it will be false. 25This makes it clear that whether either or both premisses are false, the conclusion will equally be false.
In the second figure the premisses cannot both be wholly false; for if all B is A, no middle term can be with truth universally affirmed of one extreme and universally denied of the other: 30but premisses in which the middle is affirmed of one extreme and denied of the other are the necessary condition if one is to get a valid inference at all. Therefore if, taken in this way, they are wholly false, their contraries conversely should be wholly true. But this is impossible. On the other hand, there is nothing to prevent both premisses being partially false; e.g. if actually some A is C 35and some B is C, then if it is premised that all A is C and no B is C, both premisses are false, yet partially, not wholly, false. The same is true if the major is made negative instead of the minor. Or one premiss may be wholly false, and it may be either of them. Thus, supposing that actually an attribute of all A 40must also be an attribute of all B, then if C is yet taken to be a universal attribute of all but universally non-attributable to B, C-A will be true but C-B false.
Error of attribution, then, occurs through these causes and in this form only-for we found that no syllogism of universal attribution was possible in any figure but the first. On the other hand, an error of non-attribution may occur either in the first or in the second figure. Let us therefore first explain the various forms it takes 10in the first figure and the character of the premisses in each case.
(c) It may occur when both premisses are false; e.g. supposing A atomically connected with both C and B, if it be then assumed that no C is and all B is C, both premisses are false.
(d) It is also possible when one is false. 15This may be either premiss indifferently. A-C may be true, C-B false-A-C true because A is not an attribute of all things, C-B false because C, which never has the attribute A, cannot be an attribute of B; for if C-B were true, the premiss A-C would no longer be true, and besides 20if both premisses were true, the conclusion would be true. Or again, C-B may be true and A-C false; e.g. if both C and A contain B as genera, one of them must be subordinate to the other, so that if the premiss takes the form No C is A, it will be false. 25This makes it clear that whether either or both premisses are false, the conclusion will equally be false.
In the second figure the premisses cannot both be wholly false; for if all B is A, no middle term can be with truth universally affirmed of one extreme and universally denied of the other: 30but premisses in which the middle is affirmed of one extreme and denied of the other are the necessary condition if one is to get a valid inference at all. Therefore if, taken in this way, they are wholly false, their contraries conversely should be wholly true. But this is impossible. On the other hand, there is nothing to prevent both premisses being partially false; e.g. if actually some A is C 35and some B is C, then if it is premised that all A is C and no B is C, both premisses are false, yet partially, not wholly, false. The same is true if the major is made negative instead of the minor. Or one premiss may be wholly false, and it may be either of them. Thus, supposing that actually an attribute of all A 40must also be an attribute of all B, then if C is yet taken to be a universal attribute of all but universally non-attributable to B, C-A will be true but C-B false.
80b
1 τὸ Γ, τῷ δὲ Β ὅλῳ μὴ ὑπάρχειν, ἡ μὲν Γ Α ἀληθὴς ἔσται,
ἡ δὲ Γ Β ψευδής. πάλιν ὃ τῷ Β μηδενὶ ὑπάρχει, οὐδὲ τῷ
Α παντὶ ὑπάρξει· εἰ γὰρ τῷ Α, καὶ τῷ Β· ἀλλ' οὐχ ὑπῆρχεν.
ἐὰν οὖν ληφθῇ τὸ Γ τῷ μὲν Α ὅλῳ ὑπάρχειν, τῷ δὲ
5 Β μηδενί, ἡ μὲν Γ Β πρότασις ἀληθής, ἡ δ' ἑτέρα ψευδής.
ὁμοίως δὲ καὶ μετατεθέντος τοῦ στερητικοῦ. ὃ γὰρ μηδενὶ
ὑπάρχει τῷ Α, οὐδὲ τῷ Β οὐδενὶ ὑπάρξει· ἐὰν οὖν ληφθῇ
τὸ Γ τῷ μὲν Α ὅλῳ μὴ ὑπάρχειν, τῷ δὲ Β ὅλῳ
ὑπάρχειν, ἡ μὲν Γ Α πρότασις ἀληθὴς ἔσται, ἡ ἑτέρα δὲ
10 ψευδής. καὶ πάλιν, ὃ παντὶ τῷ Β ὑπάρχει, μηδενὶ λαβεῖν
τῷ Α ὑπάρχον ψεῦδος. ἀνάγκη γάρ, εἰ τῷ Β παντί,
καὶ τῷ Α τινὶ ὑπάρχειν· ἐὰν οὖν ληφθῇ τῷ μὲν Β παντὶ
ὑπάρχειν τὸ Γ, τῷ δὲ Α μηδενί, ἡ μὲν Γ Β ἀληθὴς ἔσται,
ἡ δὲ Γ Α ψευδής. φανερὸν οὖν ὅτι καὶ ἀμφοτέρων οὐσῶν
15 ψευδῶν καὶ τῆς ἑτέρας μόνον ἔσται συλλογισμὸς ἀπατητικὸς
ἐν τοῖς ἀτόμοις.
1Again, actually that which is an attribute of no B will not be an attribute of all A either; for if it be an attribute of all A, it will also be an attribute of all B, which is contrary to supposition; but if C be nevertheless assumed to be a universal attribute of A, 5but an attribute of no B, then the premiss C-B is true but the major is false. The case is similar if the major is made the negative premiss. For in fact what is an attribute of no A will not be an attribute of any B either; and if it be yet assumed that C is universally non-attributable to A, but a universal attribute of B, the premiss C-A is true but the minor wholly false. 10Again, in fact it is false to assume that that which is an attribute of all B is an attribute of no A, for if it be an attribute of all B, it must be an attribute of some A. If then C is nevertheless assumed to be an attribute of all B but of no A, C-B will be true but C-A false.
It is thus clear that in the case of atomic propositions erroneous inference will be possible not only when both premisses are false 15but also when only one is false.
It is thus clear that in the case of atomic propositions erroneous inference will be possible not only when both premisses are false 15but also when only one is false.
Book 1,Chapter 17 (80b17–81a37)
Ἐν δὲ τοῖς μὴ ἀτόμως ὑπάρχουσιν [ἢ μὴ ὑπάρχουσιν],
ὅταν μὲν διὰ τοῦ οἰκείου μέσου γίνηται τοῦ ψεύδους ὁ
συλλογισμός, οὐχ οἷόν τε ἀμφοτέρας ψευδεῖς εἶναι τὰς
20 προτάσεις, ἀλλὰ μόνον τὴν πρὸς τῷ μείζονι ἄκρῳ. (λέγω
δ' οἰκεῖον μέσον δι' οὗ γίνεται τῆς ἀντιφάσεως ὁ συλλογισμός.)
ὑπαρχέτω γὰρ τὸ Α τῷ Β διὰ μέσου τοῦ Γ.
ἐπεὶ οὖν ἀνάγκη τὴν Γ Β καταφατικὴν λαμβάνεσθαι συλλογισμοῦ
γινομένου, δῆλον ὅτι ἀεὶ αὕτη ἔσται ἀληθής· οὐ
25 γὰρ ἀντιστρέφεται. ἡ δὲ Α Γ ψευδής· ταύτης γὰρ ἀντιστρεφομένης
ἐναντίος γίνεται ὁ συλλογισμός. ὁμοίως δὲ καὶ
εἰ ἐξ ἄλλης συστοιχίας ληφθείη τὸ μέσον, οἷον τὸ Δ εἰ
καὶ ἐν τῷ Α ὅλῳ ἐστι καὶ κατὰ τοῦ Β κατηγορεῖται παντός·
ἀνάγκη γὰρ τὴν μὲν Δ Β πρότασιν μένειν, τὴν δ'
30 ἑτέραν ἀντιστρέφεσθαι, ὥσθ' ἡ μὲν ἀεὶ ἀληθής, ἡ δ' ἀεὶ
ψευδής. καὶ σχεδὸν ἥ γε τοιαύτη ἀπάτη ἡ αὐτή ἐστι τῇ
διὰ τοῦ οἰκείου μέσου. ἐὰν δὲ μὴ διὰ τοῦ οἰκείου μέσου γίνηται
ὁ συλλογισμός, ὅταν μὲν ὑπὸ τὸ Α ᾖ τὸ μέσον, τῷ
δὲ Β μηδενὶ ὑπάρχῃ, ἀνάγκη ψευδεῖς εἶναι ἀμφοτέρας.
35 ληπτέαι γὰρ ἐναντίως ἢ ὡς ἔχουσιν αἱ προτάσεις, εἰ μέλλει
συλλογισμὸς ἔσεσθαι· οὕτω δὲ λαμβανομένων ἀμφότεραι
γίνονται ψευδεῖς. οἷον εἰ τὸ μὲν Α ὅλῳ τῷ Δ ὑπάρχει,
τὸ δὲ Δ μηδενὶ τῶν Β· ἀντιστραφέντων γὰρ τούτων
συλλογισμός τ' ἔσται καὶ αἱ προτάσεις ἀμφότεραι ψευδεῖς.
40 ὅταν δὲ μὴ ᾖ ὑπὸ τὸ Α τὸ μέσον, οἷον τὸ Δ, ἡ
17In the case of attributes not atomically connected with or disconnected from their subjects, (a, i) as long as the false conclusion is inferred through the 'appropriate' middle, only the major and not both 20premisses can be false. By 'appropriate middle' I mean the middle term through which the contradictory-i.e. the true-conclusion is inferrible. Thus, let A be attributable to B through a middle term C: then, since to produce a conclusion the premiss C-B must be taken affirmatively, it is clear that this premiss must always be true, 25for its quality is not changed. But the major A-C is false, for it is by a change in the quality of A-C that the conclusion becomes its contradictory-i.e. true. Similarly (ii) if the middle is taken from another series of predication; e.g. suppose D to be not only contained within A as a part within its whole but also predicable of all B. Then the premiss D-B must remain unchanged, 30but the quality of A-D must be changed; so that D-B is always true, A-D always false. Such error is practically identical with that which is inferred through the 'appropriate' middle. On the other hand, (b) if the conclusion is not inferred through the 'appropriate' middle-(i) when the middle is subordinate to A but is predicable of no B, both premisses must be false, 35because if there is to be a conclusion both must be posited as asserting the contrary of what is actually the fact, and so posited both become false: e.g. 40suppose that actually all D is A but no B is D; then if these premisses are changed in quality, a conclusion will follow and both of the new premisses will be false.
81a
1 μὲν Α Δ ἀληθὴς ἔσται, ἡ δὲ Δ Β ψευδής. ἡ μὲν γὰρ Α Δ
ἀληθής, ὅτι οὐκ ἦν ἐν τῷ Α τὸ Δ, ἡ δὲ Δ Β ψευδής, ὅτι
εἰ ἦν ἀληθής, κἂν τὸ συμπέρασμα ἦν ἀληθές· ἀλλ' ἦν
ψεῦδος.
5 Διὰ δὲ τοῦ μέσου σχήματος γινομένης τῆς ἀπάτης,
ἀμφοτέρας μὲν οὐκ ἐνδέχεται ψευδεῖς εἶναι τὰς προτάσεις
ὅλας (ὅταν γὰρ ᾖ τὸ Β ὑπὸ τὸ Α, οὐδὲν ἐνδέχεται τῷ μὲν
παντὶ τῷ δὲ μηδενὶ ὑπάρχειν, καθάπερ ἐλέχθη καὶ πρότερον),
τὴν ἑτέραν δ' ἐγχωρεῖ, καὶ ὁποτέραν ἔτυχεν. εἰ γὰρ
10 τὸ Γ καὶ τῷ Α καὶ τῷ Β ὑπάρχει, ἐὰν ληφθῇ τῷ μὲν Α
ὑπάρχειν τῷ δὲ Β μὴ ὑπάρχειν, ἡ μὲν Γ Α ἀληθὴς ἔσται,
ἡ δ' ἑτέρα ψευδής. πάλιν δ' εἰ τῷ μὲν Β ληφθείη τὸ Γ
ὑπάρχον, τῷ δὲ Α μηδενί, ἡ μὲν Γ Β ἀληθὴς ἔσται, ἡ δ'
ἑτέρα ψευδής.
15 Ἐὰν μὲν οὖν στερητικὸς ᾖ τῆς ἀπάτης ὁ συλλογισμός,
εἴρηται πότε καὶ διὰ τίνων ἔσται ἡ ἀπάτη· ἐὰν δὲ καταφατικός,
ὅταν μὲν διὰ τοῦ οἰκείου μέσου, ἀδύνατον ἀμφοτέρας
εἶναι ψευδεῖς· ἀνάγκη γὰρ τὴν Γ Β μένειν, εἴπερ ἔσται
συλλογισμός, καθάπερ ἐλέχθη καὶ πρότερον. ὥστε ἡ Α Γ
20 ἀεὶ ἔσται ψευδής· αὕτη γάρ ἐστιν ἡ ἀντιστρεφομένη. ὁμοίως
δὲ καὶ εἰ ἐξ ἄλλης συστοιχίας λαμβάνοιτο τὸ μέσον, ὥςπερ
ἐλέχθη καὶ ἐπὶ τῆς στερητικῆς ἀπάτης· ἀνάγκη γὰρ
τὴν μὲν Δ Β μένειν, τὴν δ' Α Δ ἀντιστρέφεσθαι, καὶ ἡ
ἀπάτη ἡ αὐτὴ τῇ πρότερον. ὅταν δὲ μὴ διὰ τοῦ οἰκείου, ἐὰν
25 μὲν ᾖ τὸ Δ ὑπὸ τὸ Α, αὕτη μὲν ἔσται ἀληθής, ἡ ἑτέρα δὲ
ψευδής· ἐγχωρεῖ γὰρ τὸ Α πλείοσιν ὑπάρχειν ἃ οὐκ ἔστιν
ὑπ' ἄλληλα. ἐὰν δὲ μὴ ᾖ τὸ Δ ὑπὸ τὸ Α, αὕτη μὲν ἀεὶ
δῆλον ὅτι ἔσται ψευδής (καταφατικὴ γὰρ λαμβάνεται),
τὴν δὲ Δ Β ἐνδέχεται καὶ ἀληθῆ εἶναι καὶ ψευδῆ· οὐδὲν
30 γὰρ κωλύει τὸ μὲν Α τῷ Δ μηδενὶ ὑπάρχειν, τὸ δὲ Δ
τῷ Β παντί, οἷον ζῷον ἐπιστήμῃ, ἐπιστήμη δὲ μουσικῇ. οὐδ'
αὖ μήτε τὸ Α μηδενὶ τῶν Δ μήτε τὸ Δ μηδενὶ τῶν Β.
[φανερὸν οὖν ὅτι μὴ ὄντος τοῦ μέσου ὑπὸ τὸ Α καὶ ἀμφοτέρας
ἐγχωρεῖ ψευδεῖς εἶναι καὶ ὁποτέραν ἔτυχεν.]
35 Ποσαχῶς μὲν οὖν καὶ διὰ τίνων ἐγχωρεῖ γίνεσθαι τὰς
κατὰ συλλογισμὸν ἀπάτας ἔν τε τοῖς ἀμέσοις καὶ ἐν τοῖς
δι' ἀποδείξεως, φανερόν.
1When, however, (ii) the middle D is not subordinate to A, A-D will be true, D-B false-A-D true because A was not subordinate to D, D-B false because if it had been true, the conclusion too would have been true; but it is ex hypothesi false.
5When the erroneous inference is in the second figure, both premisses cannot be entirely false; since if B is subordinate to A, there can be no middle predicable of all of one extreme and of none of the other, as was stated before. One premiss, however, may be false, and it may be either of them. Thus, if 10C is actually an attribute of both A and B, but is assumed to be an attribute of A only and not of B, C-A will be true, C-B false: or again if C be assumed to be attributable to B but to no A, C-B will be true, C-A false.
15We have stated when and through what kinds of premisses error will result in cases where the erroneous conclusion is negative. If the conclusion is affirmative, (a, i) it may be inferred through the 'appropriate' middle term. In this case both premisses cannot be false since, as we said before, C-B must remain unchanged if there is to be a conclusion, and consequently A-C, the quality of which is changed, 20will always be false. This is equally true if (ii) the middle is taken from another series of predication, as was stated to be the case also with regard to negative error; for D-B must remain unchanged, while the quality of A-D must be converted, and the type of error is the same as before.
(b) The middle may be inappropriate. Then (i) 25if D is subordinate to A, A-D will be true, but D-B false; since A may quite well be predicable of several terms no one of which can be subordinated to another. If, however, (ii) D is not subordinate to A, obviously A-D, since it is affirmed, will always be false, while D-B may be either true or false; 30for A may very well be an attribute of no D, whereas all B is D, e.g. no science is animal, all music is science. Equally well A may be an attribute of no D, and D of no B. It emerges, then, that if the middle term is not subordinate to the major, not only both premisses but either singly may be false.
35Thus we have made it clear how many varieties of erroneous inference are liable to happen and through what kinds of premisses they occur, in the case both of immediate and of demonstrable truths.
5When the erroneous inference is in the second figure, both premisses cannot be entirely false; since if B is subordinate to A, there can be no middle predicable of all of one extreme and of none of the other, as was stated before. One premiss, however, may be false, and it may be either of them. Thus, if 10C is actually an attribute of both A and B, but is assumed to be an attribute of A only and not of B, C-A will be true, C-B false: or again if C be assumed to be attributable to B but to no A, C-B will be true, C-A false.
15We have stated when and through what kinds of premisses error will result in cases where the erroneous conclusion is negative. If the conclusion is affirmative, (a, i) it may be inferred through the 'appropriate' middle term. In this case both premisses cannot be false since, as we said before, C-B must remain unchanged if there is to be a conclusion, and consequently A-C, the quality of which is changed, 20will always be false. This is equally true if (ii) the middle is taken from another series of predication, as was stated to be the case also with regard to negative error; for D-B must remain unchanged, while the quality of A-D must be converted, and the type of error is the same as before.
(b) The middle may be inappropriate. Then (i) 25if D is subordinate to A, A-D will be true, but D-B false; since A may quite well be predicable of several terms no one of which can be subordinated to another. If, however, (ii) D is not subordinate to A, obviously A-D, since it is affirmed, will always be false, while D-B may be either true or false; 30for A may very well be an attribute of no D, whereas all B is D, e.g. no science is animal, all music is science. Equally well A may be an attribute of no D, and D of no B. It emerges, then, that if the middle term is not subordinate to the major, not only both premisses but either singly may be false.
35Thus we have made it clear how many varieties of erroneous inference are liable to happen and through what kinds of premisses they occur, in the case both of immediate and of demonstrable truths.
Book 1,Chapter 18 (81a38–81b9)
Φανερὸν δὲ καὶ ὅτι, εἴ τις αἴσθησις ἐκλέλοιπεν, ἀνάγκη
καὶ ἐπιστήμην τινὰ ἐκλελοιπέναι, ἣν ἀδύνατον λαβεῖν, εἴπερ
40 μανθάνομεν ἢ ἐπαγωγῇ ἢ ἀποδείξει, ἔστι δ' ἡ μὲν ἀπόδειξις
38It is also clear that the loss of any one of the senses entails the loss of a corresponding portion of knowledge, and that, 40since we learn either by induction or by demonstration, this knowledge cannot be acquired.
81b
1 ἐκ τῶν καθόλου, ἡ δ' ἐπαγωγὴ ἐκ τῶν κατὰ μέρος,
ἀδύνατον δὲ τὰ καθόλου θεωρῆσαι μὴ δι' ἐπαγωγῆς (ἐπεὶ
καὶ τὰ ἐξ ἀφαιρέσεως λεγόμενα ἔσται δι' ἐπαγωγῆς γνώριμα
ποιεῖν, ὅτι ὑπάρχει ἑκάστῳ γένει ἔνια, καὶ εἰ μὴ χωριστά
5 ἐστιν, ᾗ τοιονδὶ ἕκαστον), ἐπαχθῆναι δὲ μὴ ἔχοντας αἴσθησιν
ἀδύνατον. τῶν γὰρ καθ' ἕκαστον ἡ αἴσθησις· οὐ γὰρ
ἐνδέχεται λαβεῖν αὐτῶν τὴν ἐπιστήμην· οὔτε γὰρ ἐκ τῶν καθόλου
ἄνευ ἐπαγωγῆς, οὔτε δι' ἐπαγωγῆς ἄνευ τῆς αἰσθήσεως.
1Thus demonstration develops from universals, induction from particulars; but since it is possible to familiarize the pupil with even the so-called mathematical abstractions only through induction-i.e. only because each subject genus possesses, in virtue of a determinate mathematical character, certain properties which can be treated as separate even though they do not exist in isolation-it is consequently impossible to come to grasp universals except through induction. 5But induction is impossible for those who have not sense-perception. For it is sense-perception alone which is adequate for grasping the particulars: they cannot be objects of scientific knowledge, because neither can universals give us knowledge of them without induction, nor can we get it through induction without sense-perception.
Book 1,Chapter 19 (81b10–82a20)
10 Ἔστι δὲ πᾶς συλλογισμὸς διὰ τριῶν ὅρων, καὶ ὁ μὲν
δεικνύναι δυνάμενος ὅτι ὑπάρχει τὸ Α τῷ Γ διὰ τὸ ὑπάρχειν
τῷ Β καὶ τοῦτο τῷ Γ, ὁ δὲ στερητικός, τὴν μὲν ἑτέραν
πρότασιν ἔχων ὅτι ὑπάρχει τι ἄλλο ἄλλῳ, τὴν δ' ἑτέραν
ὅτι οὐχ ὑπάρχει. φανερὸν οὖν ὅτι αἱ μὲν ἀρχαὶ καὶ αἱ λεγόμεναι
15 ὑποθέσεις αὗταί εἰσι· λαβόντα γὰρ ταῦτα οὕτως
ἀνάγκη δεικνύναι, οἷον ὅτι τὸ Α τῷ Γ ὑπάρχει διὰ τοῦ Β,
πάλιν δ' ὅτι τὸ Α τῷ Β δι' ἄλλου μέσου, καὶ ὅτι τὸ Β
τῷ Γ ὡσαύτως. κατὰ μὲν οὖν δόξαν συλλογιζομένοις καὶ
μόνον διαλεκτικῶς δῆλον ὅτι τοῦτο μόνον σκεπτέον, εἰ ἐξ ὧν
20 ἐνδέχεται ἐνδοξοτάτων γίνεται ὁ συλλογισμός, ὥστ' εἰ καὶ
μὴ ἔστι τι τῇ ἀληθείᾳ τῶν Α Β μέσον, δοκεῖ δὲ εἶναι, ὁ
διὰ τούτου συλλογιζόμενος συλλελόγισται διαλεκτικῶς· πρὸς
δ' ἀλήθειαν ἐκ τῶν ὑπαρχόντων δεῖ σκοπεῖν. ἔχει δ' οὕτως·
ἐπειδὴ ἔστιν ὃ αὐτὸ μὲν κατ' ἄλλου κατηγορεῖται μὴ κατὰ
25 συμβεβηκός—λέγω δὲ τὸ κατὰ συμβεβηκός, οἷον τὸ λευκόν
ποτ' ἐκεῖνό φαμεν εἶναι ἄνθρωπον, οὐχ ὁμοίως λέγοντες
καὶ τὸν ἄνθρωπον λευκόν· ὁ μὲν γὰρ οὐχ ἕτερόν τι ὢν λευκός
ἐστι, τὸ δὲ λευκόν, ὅτι συμβέβηκε τῷ ἀνθρώπῳ εἶναι
λευκῷ—ἔστιν οὖν ἔνια τοιαῦτα ὥστε καθ' αὑτὰ κατηγορεῖσθαι.
30 Ἔστω δὴ τὸ Γ τοιοῦτον ὃ αὐτὸ μὲν μηκέτι ὑπάρχει ἄλλῳ,
τούτῳ δὲ τὸ Β πρώτῳ, καὶ οὐκ ἔστιν ἄλλο μεταξύ. καὶ
πάλιν τὸ Ε τῷ Ζ ὡσαύτως, καὶ τοῦτο τῷ Β. ἆρ' οὖν τοῦτο
ἀνάγκη στῆναι, ἢ ἐνδέχεται εἰς ἄπειρον ἰέναι; καὶ πάλιν εἰ
τοῦ μὲν Α μηδὲν κατηγορεῖται καθ' αὑτό, τὸ δὲ Α τῷ Θ
35 ὑπάρχει πρώτῳ, μεταξὺ δὲ μηδενὶ προτέρῳ, καὶ τὸ Θ τῷ
Η, καὶ τοῦτο τῷ Β, ἆρα καὶ τοῦτο ἵστασθαι ἀνάγκη, ἢ καὶ
τοῦτ' ἐνδέχεται εἰς ἄπειρον ἰέναι; διαφέρει δὲ τοῦτο τοῦ πρότερον
τοσοῦτον, ὅτι τὸ μέν ἐστιν, ἆρα ἐνδέχεται ἀρξαμένῳ
ἀπὸ τοιούτου ὃ μηδενὶ ὑπάρχει ἑτέρῳ ἀλλ' ἄλλο ἐκείνῳ, ἐπὶ
40 τὸ ἄνω εἰς ἄπειρον ἰέναι, θάτερον δὲ ἀρξάμενον ἀπὸ τοιούτου
10Every syllogism is effected by means of three terms. One kind of syllogism serves to prove that A inheres in C by showing that A inheres in B and B in C; the other is negative and one of its premisses asserts one term of another, while the other denies one term of another. It is clear, then, that these are the fundamentals and so-called 15hypotheses of syllogism. Assume them as they have been stated, and proof is bound to follow-proof that A inheres in C through B, and again that A inheres in B through some other middle term, and similarly that B inheres in C. If our reasoning aims at gaining credence and so is merely dialectical, it is obvious that we have only to see that our inference is 20based on premisses as credible as possible: so that if a middle term between A and B is credible though not real, one can reason through it and complete a dialectical syllogism. If, however, one is aiming at truth, one must be guided by the real connexions of subjects and attributes. Thus: since there are attributes which are predicated of a subject essentially or naturally and not 25coincidentally-not, that is, in the sense in which we say 'That white (thing) is a man', which is not the same mode of predication as when we say 'The man is white': the man is white not because he is something else but because he is man, but the white is man because 'being white' coincides with 'humanity' within one substratum-therefore there are terms such as are naturally subjects of predicates. 30Suppose, then, C such a term not itself attributable to anything else as to a subject, but the proximate subject of the attribute B--i.e. so that B-C is immediate; suppose further E related immediately to F, and F to B. The first question is, must this series terminate, or can it proceed to infinity? The second question is as follows: Suppose nothing is essentially predicated of A, but A 35is predicated primarily of H and of no intermediate prior term, and suppose H similarly related to G and G to B; then must this series also terminate, or can it too proceed to infinity? There is this much difference between the questions: the first is, is it possible to start from that which is not itself attributable to anything else but is the subject of attributes, and 40ascend to infinity? The second is the problem whether one can start from that which is a predicate but not itself a subject of predicates, and descend to infinity?
82a
1 ὃ αὐτὸ μὲν ἄλλου, ἐκείνου δὲ μηδὲν κατηγορεῖται, ἐπὶ τὸ
κάτω σκοπεῖν εἰ ἐνδέχεται εἰς ἄπειρον ἰέναι. Ἔτι τὰ μεταξὺ
ἆρ' ἐνδέχεται ἄπειρα εἶναι ὡρισμένων τῶν ἄκρων; λέγω δ'
οἷον εἰ τὸ Α τῷ Γ ὑπάρχει, μέσον δ' αὐτῶν τὸ Β, τοῦ
5 δὲ Β καὶ τοῦ Α ἕτερα, τούτων δ' ἄλλα, ἆρα καὶ ταῦτα
εἰς ἄπειρον ἐνδέχεται ἰέναι, ἢ ἀδύνατον; ἔστι δὲ τοῦτο σκοπεῖν
ταὐτὸ καὶ εἰ αἱ ἀποδείξεις εἰς ἄπειρον ἔρχονται, καὶ
εἰ ἔστιν ἀπόδειξις ἅπαντος, ἢ πρὸς ἄλληλα περαίνεται.
Ὁμοίως δὲ λέγω καὶ ἐπὶ τῶν στερητικῶν συλλογισμῶν
10 καὶ προτάσεων, οἷον εἰ τὸ Α μὴ ὑπάρχει τῷ Β μηδενί, ἤτοι
πρώτῳ, ἢ ἔσται τι μεταξὺ ᾧ προτέρῳ οὐχ ὑπάρχει (οἷον εἰ
τῷ Η, ὃ τῷ Β ὑπάρχει παντί), καὶ πάλιν τούτου ἔτι ἄλλῳ
προτέρῳ, οἷον εἰ τῷ Θ, ὃ τῷ Η παντὶ ὑπάρχει. καὶ γὰρ
ἐπὶ τούτων ἢ ἄπειρα οἷς ὑπάρχει προτέροις, ἢ ἵσταται.
15 Ἐπὶ δὲ τῶν ἀντιστρεφόντων οὐχ ὁμοίως ἔχει. οὐ γὰρ
ἔστιν ἐν τοῖς ἀντικατηγορουμένοις οὗ πρώτου κατηγορεῖται ἢ
τελευταίου πάντα γὰρ πρὸς πάντα ταύτῃ γε ὁμοίως ἔχει, εἴτ'
ἐστὶν ἄπειρα τὰ κατ' αὐτοῦ κατηγορούμενα, εἴτ' ἀμφότερά ἐστι
τὰ ἀπορηθέντα ἄπειρα· πλὴν εἰ μὴ ὁμοίως ἐνδέχεται ἀντιστρέφειν,
20 ἀλλὰ τὸ μὲν ὡς συμβεβηκός, τὸ δ' ὡς κατηγορίαν.
1A third question is, if the extreme terms are fixed, can there be an infinity of middles? I mean this: suppose for example that A inheres in C and B is intermediate between them, but 5between B and A there are other middles, and between these again fresh middles; can these proceed to infinity or can they not? This is the equivalent of inquiring, do demonstrations proceed to infinity, i.e. is everything demonstrable? Or do ultimate subject and primary attribute limit one another?
I hold that the same questions arise with regard to negative conclusions 10and premisses: viz. if A is attributable to no B, then either this predication will be primary, or there will be an intermediate term prior to B to which a is not attributable-G, let us say, which is attributable to all B-and there may still be another term H prior to G, which is attributable to all G. The same questions arise, I say, because in these cases too either the series of prior terms to which a is not attributable is infinite or it terminates.
15One cannot ask the same questions in the case of reciprocating terms, since when subject and predicate are convertible there is neither primary nor ultimate subject, seeing that all the reciprocals qua subjects stand in the same relation to one another, whether we say that the subject has an infinity of attributes or that both subjects and attributes-and we raised the question in both cases-are infinite in number. These questions then cannot be asked-unless, indeed, the terms can reciprocate by two different modes, 20by accidental predication in one relation and natural predication in the other.
I hold that the same questions arise with regard to negative conclusions 10and premisses: viz. if A is attributable to no B, then either this predication will be primary, or there will be an intermediate term prior to B to which a is not attributable-G, let us say, which is attributable to all B-and there may still be another term H prior to G, which is attributable to all G. The same questions arise, I say, because in these cases too either the series of prior terms to which a is not attributable is infinite or it terminates.
15One cannot ask the same questions in the case of reciprocating terms, since when subject and predicate are convertible there is neither primary nor ultimate subject, seeing that all the reciprocals qua subjects stand in the same relation to one another, whether we say that the subject has an infinity of attributes or that both subjects and attributes-and we raised the question in both cases-are infinite in number. These questions then cannot be asked-unless, indeed, the terms can reciprocate by two different modes, 20by accidental predication in one relation and natural predication in the other.
Book 1,Chapter 20 (82a21–35)
Ὅτι μὲν οὖν τὰ μεταξὺ οὐκ ἐνδέχεται ἄπειρα εἶναι, εἰ
ἐπὶ τὸ κάτω καὶ τὸ ἄνω ἵστανται αἱ κατηγορίαι, δῆλον.
λέγω δ' ἄνω μὲν τὴν ἐπὶ τὸ καθόλου μᾶλλον, κάτω δὲ
τὴν ἐπὶ τὸ κατὰ μέρος. εἰ γὰρ τοῦ Α κατηγορουμένου κατὰ
25 τοῦ Ζ ἄπειρα τὰ μεταξύ, ἐφ' ὧν Β, δῆλον ὅτι ἐνδέχοιτ'
ἂν ὥστε καὶ ἀπὸ τοῦ Α ἐπὶ τὸ κάτω ἕτερον ἑτέρου κατηγορεῖσθαι
εἰς ἄπειρον (πρὶν γὰρ ἐπὶ τὸ Ζ ἐλθεῖν, ἄπειρα τὰ
μεταξύ) καὶ ἀπὸ τοῦ Ζ ἐπὶ τὸ ἄνω ἄπειρα, πρὶν ἐπὶ τὸ Α
ἐλθεῖν. ὥστ' εἰ ταῦτα ἀδύνατα, καὶ τοῦ Α καὶ Ζ ἀδύνατον
30 ἄπειρα εἶναι μεταξύ. οὐδὲ γὰρ εἴ τις λέγοι ὅτι τὰ μέν ἐστι
τῶν Α Β Ζ ἐχόμενα ἀλλήλων ὥστε μὴ εἶναι μεταξύ, τὰ δ' οὐκ
ἔστι λαβεῖν, οὐδὲν διαφέρει. ὃ γὰρ ἂν λάβω τῶν Β, ἔσται
πρὸς τὸ Α ἢ πρὸς τὸ Ζ ἢ ἄπειρα τὰ μεταξὺ ἢ οὔ. ἀφ'
οὗ δὴ πρῶτον ἄπειρα, εἴτ' εὐθὺς εἴτε μὴ εὐθύς, οὐδὲν διαφέρει·
35 τὰ γὰρ μετὰ ταῦτα ἄπειρά ἐστιν.
21Now, it is clear that if the predications terminate in both the upward and the downward direction (by 'upward' I mean the ascent to the more universal, by 'downward' the descent to the more particular), the middle terms cannot be infinite in number. For suppose that A is predicated 25of F, and that the intermediates-call them BB'B"...-are infinite, then clearly you might descend from and find one term predicated of another ad infinitum, since you have an infinity of terms between you and F; and equally, if you ascend from F, there are infinite terms between you and A. It follows that if these processes are impossible there cannot be 30an infinity of intermediates between A and F. Nor is it of any effect to urge that some terms of the series AB...F are contiguous so as to exclude intermediates, while others cannot be taken into the argument at all: whichever terms of the series B...I take, the number of intermediates in the direction either of A or of F must be finite or infinite: where the infinite series starts, whether from the first term or from a later one, is of no moment, 35for the succeeding terms in any case are infinite in number.
Book 1,Chapter 21 (82a36–82b36)
Φανερὸν δὲ καὶ ἐπὶ τῆς στερητικῆς ἀποδείξεως ὅτι στήσεται,
εἴπερ ἐπὶ τῆς κατηγορικῆς ἵσταται ἐπ' ἀμφότερα.
ἔστω γὰρ μὴ ἐνδεχόμενον μήτε ἐπὶ τὸ ἄνω ἀπὸ τοῦ ὑστάτου
εἰς ἄπειρον ἰέναι (λέγω δ' ὕστατον ὃ αὐτὸ μὲν ἄλλῳ
36Further, if in affirmative demonstration the series terminates in both directions, clearly it will terminate too in negative demonstration.
82b
1 μηδενὶ ὑπάρχει, ἐκείνῳ δὲ ἄλλο, οἷον τὸ Ζ) μήτε ἀπὸ τοῦ
πρώτου ἐπὶ τὸ ὕστατον (λέγω δὲ πρῶτον ὃ αὐτὸ μὲν κατ'
ἄλλου, κατ' ἐκείνου δὲ μηδὲν ἄλλο). εἰ δὴ ταῦτ' ἔστι, καὶ
ἐπὶ τῆς ἀποφάσεως στήσεται. τριχῶς γὰρ δείκνυται μὴ
5 ὑπάρχον. ἢ γὰρ ᾧ μὲν τὸ Γ, τὸ Β ὑπάρχει παντί, ᾧ δὲ
τὸ Β, οὐδενὶ τὸ Α. τοῦ μὲν τοίνυν Β Γ, καὶ ἀεὶ τοῦ ἑτέρου
διαστήματος, ἀνάγκη βαδίζειν εἰς ἄμεσα· κατηγορικὸν γὰρ
τοῦτο τὸ διάστημα. τὸ δ' ἕτερον δῆλον ὅτι εἰ ἄλλῳ οὐχ ὑπάρχει
προτέρῳ, οἷον τῷ Δ, τοῦτο δεήσει τῷ Β παντὶ ὑπάρχειν.
10 καὶ εἰ πάλιν ἄλλῳ τοῦ Δ προτέρῳ οὐχ ὑπάρχει, ἐκεῖνο
δεήσει τῷ Δ παντὶ ὑπάρχειν. ὥστ' ἐπεὶ ἡ ἐπὶ τὸ ἄνω ἵσταται
ὁδός, καὶ ἡ ἐπὶ τὸ Α στήσεται, καὶ ἔσται τι πρῶτον
ᾧ οὐχ ὑπάρχει. Πάλιν εἰ τὸ μὲν Β παντὶ τῷ Α, τῷ δὲ Γ
μηδενί, τὸ Α τῶν Γ οὐδενὶ ὑπάρχει. πάλιν τοῦτο εἰ δεῖ δεῖξαι,
15 δῆλον ὅτι ἢ διὰ τοῦ ἄνω τρόπου δειχθήσεται ἢ διὰ
τούτου ἢ τοῦ τρίτου. ὁ μὲν οὖν πρῶτος εἴρηται, ὁ δὲ δεύτερος
δειχθήσεται. οὕτω δ' ἂν δεικνύοι, οἷον τὸ Δ τῷ μὲν
Β παντὶ ὑπάρχει, τῷ δὲ Γ οὐδενί, εἰ ἀνάγκη ὑπάρχειν τι
τῷ Β. καὶ πάλιν εἰ τοῦτο τῷ Γ μὴ ὑπάρξει, ἄλλο τῷ Δ
20 ὑπάρχει, ὃ τῷ Γ οὐχ ὑπάρχει. οὐκοῦν ἐπεὶ τὸ ὑπάρχειν
ἀεὶ τῷ ἀνωτέρω ἵσταται, στήσεται καὶ τὸ μὴ ὑπάρχειν. Ὁ
δὲ τρίτος τρόπος ἦν· εἰ τὸ μὲν Α τῷ Β παντὶ ὑπάρχει, τὸ
δὲ Γ μὴ ὑπάρχει, οὐ παντὶ ὑπάρχει τὸ Γ ᾧ τὸ Α. πάλιν
δὲ τοῦτο ἢ διὰ τῶν ἄνω εἰρημένων ἢ ὁμοίως δειχθήσεται.
25 ἐκείνως μὲν δὴ ἵσταται, εἰ δ' οὕτω, πάλιν λήψεται τὸ Β
τῷ Ε ὑπάρχειν, ᾧ τὸ Γ μὴ παντὶ ὑπάρχει. καὶ τοῦτο πάλιν
ὁμοίως. ἐπεὶ δ' ὑπόκειται ἵστασθαι καὶ ἐπὶ τὸ κάτω,
δῆλον ὅτι στήσεται καὶ τὸ Γ οὐχ ὑπάρχον.
Φανερὸν δ' ὅτι καὶ ἐὰν μὴ μιᾷ ὁδῷ δεικνύηται ἀλλὰ πάσαις,
30 ὁτὲ μὲν ἐκ τοῦ πρώτου σχήματος, ὁτὲ δὲ ἐκ τοῦ δευτέρου
ἢ τρίτου, ὅτι καὶ οὕτω στήσεται· πεπερασμέναι γάρ εἰσιν αἱ
ὁδοί, τὰ δὲ πεπερασμένα πεπερασμενάκις ἀνάγκη πεπεράνθαι
πάντα.
Ὅτι μὲν οὖν ἐπὶ τῆς στερήσεως, εἴπερ καὶ ἐπὶ τοῦ ὑπάρχειν,
35 ἵσταται, δῆλον. ὅτι δ' ἐπ' ἐκείνων, λογικῶς μὲν
θεωροῦσιν ὧδε φανερόν.
1Let us assume that we cannot proceed to infinity either by ascending from the ultimate term (by 'ultimate term' I mean a term such as was, not itself attributable to a subject but itself the subject of attributes), or by descending towards an ultimate from the primary term (by 'primary term' I mean a term predicable of a subject but not itself a subject). If this assumption is justified, the series will also terminate in the case of negation. For a negative conclusion can be proved in all three figures. 5In the first figure it is proved thus: no B is A, all C is B. In packing the interval B-C we must reach immediate propositions--as is always the case with the minor premiss--since B-C is affirmative. As regards the other premiss it is plain that if the major term is denied of a term D prior to B, D will have to be predicable of all B, 10and if the major is denied of yet another term prior to D, this term must be predicable of all D. Consequently, since the ascending series is finite, the descent will also terminate and there will be a subject of which A is primarily non-predicable. In the second figure the syllogism is, all A is B, no C is B,..no C is A. If proof of this is required, 15plainly it may be shown either in the first figure as above, in the second as here, or in the third. The first figure has been discussed, and we will proceed to display the second, proof by which will be as follows: all B is D, no C is D..., since it is required that B should be a subject of which a predicate is affirmed. Next, since D is to be proved not to belong to C, then D has a further predicate 20which is denied of C. Therefore, since the succession of predicates affirmed of an ever higher universal terminates, the succession of predicates denied terminates too.
The third figure shows it as follows: all B is A, some B is not C. Therefore some A is not C. This premiss, i.e. C-B, will be proved either in the same figure or in one of the two figures discussed above. 25In the first and second figures the series terminates. If we use the third figure, we shall take as premisses, all E is B, some E is not C, and this premiss again will be proved by a similar prosyllogism. But since it is assumed that the series of descending subjects also terminates, plainly the series of more universal non-predicables will terminate also. Even supposing that the proof is not confined to one method, but employs them all and is 30now in the first figure, now in the second or third-even so the regress will terminate, for the methods are finite in number, and if finite things are combined in a finite number of ways, the result must be finite.
35Thus it is plain that the regress of middles terminates in the case of negative demonstration, if it does so also in the case of affirmative demonstration. That in fact the regress terminates in both these cases may be made clear by the following dialectical considerations.
The third figure shows it as follows: all B is A, some B is not C. Therefore some A is not C. This premiss, i.e. C-B, will be proved either in the same figure or in one of the two figures discussed above. 25In the first and second figures the series terminates. If we use the third figure, we shall take as premisses, all E is B, some E is not C, and this premiss again will be proved by a similar prosyllogism. But since it is assumed that the series of descending subjects also terminates, plainly the series of more universal non-predicables will terminate also. Even supposing that the proof is not confined to one method, but employs them all and is 30now in the first figure, now in the second or third-even so the regress will terminate, for the methods are finite in number, and if finite things are combined in a finite number of ways, the result must be finite.
35Thus it is plain that the regress of middles terminates in the case of negative demonstration, if it does so also in the case of affirmative demonstration. That in fact the regress terminates in both these cases may be made clear by the following dialectical considerations.
Book 1,Chapter 22 (82b37–84b2)
Ἐπὶ μὲν οὖν τῶν ἐν τῷ τί ἐστι κατηγορουμένων δῆλον·
εἰ γὰρ ἔστιν ὁρίσασθαι ἢ εἰ γνωστὸν τὸ τί ἦν εἶναι, τὰ δ'
ἄπειρα μὴ ἔστι διελθεῖν, ἀνάγκη πεπεράνθαι τὰ ἐν τῷ τί
37In the case of predicates constituting the essential nature of a thing, it clearly terminates, seeing that if definition is possible, or in other words, if essential form is knowable, and an infinite series cannot be traversed, predicates constituting a thing's essential nature must be finite in number.
83a
1 ἐστι κατηγορούμενα. καθόλου δὲ ὧδε λέγομεν. ἔστι γὰρ εἰπεῖν
ἀληθῶς τὸ λευκὸν βαδίζειν καὶ τὸ μέγα ἐκεῖνο ξύλον
εἶναι, καὶ πάλιν τὸ ξύλον μέγα εἶναι καὶ τὸν ἄνθρωπον βαδίζειν.
ἕτερον δή ἐστι τὸ οὕτως εἰπεῖν καὶ τὸ ἐκείνως. ὅταν
5 μὲν γὰρ τὸ λευκὸν εἶναι φῶ ξύλον, τότε λέγω ὅτι ᾧ συμβέβηκε
λευκῷ εἶναι ξύλον ἐστίν, ἀλλ' οὐχ ὡς τὸ ὑποκείμενον
τῷ ξύλῳ τὸ λευκόν ἐστι· καὶ γὰρ οὔτε λευκὸν ὂν οὔθ' ὅπερ
λευκόν τι ἐγένετο ξύλον, ὥστ' οὐκ ἔστιν ἀλλ' ἢ κατὰ συμβεβηκός.
ὅταν δὲ τὸ ξύλον λευκὸν εἶναι φῶ, οὐχ ὅτι ἕτερόν
10 τί ἐστι λευκόν, ἐκείνῳ δὲ συμβέβηκε ξύλῳ εἶναι, οἷον ὅταν
τὸ μουσικὸν λευκὸν εἶναι φῶ (τότε γὰρ ὅτι ὁ ἄνθρωπος
λευκός ἐστιν, ᾧ συμβέβηκεν εἶναι μουσικῷ, λέγω), ἀλλὰ
τὸ ξύλον ἐστὶ τὸ ὑποκείμενον, ὅπερ καὶ ἐγένετο, οὐχ ἕτερόν
τι ὂν ἢ ὅπερ ξύλον ἢ ξύλον τί. εἰ δὴ δεῖ νομοθετῆσαι, ἔστω
15 τὸ οὕτω λέγειν κατηγορεῖν, τὸ δ' ἐκείνως ἤτοι μηδαμῶς
κατηγορεῖν, ἢ κατηγορεῖν μὲν μὴ ἁπλῶς, κατὰ συμβεβηκὸς
δὲ κατηγορεῖν. ἔστι δ' ὡς μὲν τὸ λευκὸν τὸ κατηγορούμενον,
ὡς δὲ τὸ ξύλον τὸ οὗ κατηγορεῖται. ὑποκείσθω δὴ
τὸ κατηγορούμενον κατηγορεῖσθαι ἀεί, οὗ κατηγορεῖται,
20 ἁπλῶς, ἀλλὰ μὴ κατὰ συμβεβηκός· οὕτω γὰρ αἱ ἀποδείξεις
ἀποδεικνύουσιν. ὥστε ἢ ἐν τῷ τί ἐστιν ἢ ὅτι ποιὸν ἢ ποσὸν
ἢ πρός τι ἢ ποιοῦν τι ἢ πάσχον ἢ ποὺ ἢ ποτέ, ὅταν ἓν καθ'
ἑνὸς κατηγορηθῇ.
Ἔτι τὰ μὲν οὐσίαν σημαίνοντα ὅπερ ἐκεῖνο ἢ ὅπερ
25 ἐκεῖνό τι σημαίνει καθ' οὗ κατηγορεῖται· ὅσα δὲ μὴ οὐσίαν
σημαίνει, ἀλλὰ κατ' ἄλλου ὑποκειμένου λέγεται
ὃ μὴ ἔστι μήτε ὅπερ ἐκεῖνο μήτε ὅπερ ἐκεῖνό τι, συμβεβηκότα,
οἷον κατὰ τοῦ ἀνθρώπου τὸ λευκόν. οὐ γάρ ἐστιν
ὁ ἄνθρωπος οὔτε ὅπερ λευκὸν οὔτε ὅπερ λευκόν τι, ἀλλὰ ζῷον
30 ἴσως· ὅπερ γὰρ ζῷόν ἐστιν ὁ ἄνθρωπος. ὅσα δὲ μὴ οὐσίαν
σημαίνει, δεῖ κατά τινος ὑποκειμένου κατηγορεῖσθαι, καὶ
μὴ εἶναί τι λευκὸν ὃ οὐχ ἕτερόν τι ὂν λευκόν ἐστιν. τὰ
γὰρ εἴδη χαιρέτω· τερετίσματά τε γάρ ἐστι, καὶ εἰ ἔστιν,
οὐδὲν πρὸς τὸν λόγον ἐστίν· αἱ γὰρ ἀποδείξεις περὶ τῶν τοιούτων
35 εἰσίν.
Ἔτι εἰ μὴ ἔστι τόδε τοῦδε ποιότης κἀκεῖνο τούτου, μηδὲ
ποιότητος ποιότης, ἀδύνατον ἀντικατηγορεῖσθαι ἀλλήλων
οὕτως, ἀλλ' ἀληθὲς μὲν ἐνδέχεται εἰπεῖν, ἀντικατηγορῆσαι
δ' ἀληθῶς οὐκ ἐνδέχεται. ἢ γάρ τοι ὡς οὐσία κατηγορηθήσεται,
1But as regards predicates generally we have the following prefatory remarks to make. (1) We can affirm without falsehood 'the white (thing) is walking', and that big (thing) is a log'; or again, 'the log is big', and 'the man walks'. But the affirmation differs in the two cases. 5When I affirm 'the white is a log', I mean that something which happens to be white is a log-not that white is the substratum in which log inheres, for it was not qua white or qua a species of white that the white (thing) came to be a log, and the white (thing) is consequently not a log except incidentally. On the other hand, when I affirm 'the log is white', I do not mean that something else, 10which happens also to be a log, is white (as I should if I said 'the musician is white,' which would mean 'the man who happens also to be a musician is white'); on the contrary, log is here the substratum-the substratum which actually came to be white, and did so qua wood or qua a species of wood and qua nothing else.
15If we must lay down a rule, let us entitle the latter kind of statement predication, and the former not predication at all, or not strict but accidental predication. 'White' and 'log' will thus serve as types respectively of predicate and subject.
We shall assume, then, that the predicate is invariably predicated 20strictly and not accidentally of the subject, for on such predication demonstrations depend for their force. It follows from this that when a single attribute is predicated of a single subject, the predicate must affirm of the subject either some element constituting its essential nature, or that it is in some way qualified, quantified, essentially related, active, passive, placed, or dated.
(2) Predicates which signify substance signify that the subject is identical with the predicate 25or with a species of the predicate. Predicates not signifying substance which are predicated of a subject not identical with themselves or with a species of themselves are accidental or coincidental; e.g. white is a coincident of man, seeing that man is not identical with white or a species of white, 30but rather with animal, since man is identical with a species of animal. These predicates which do not signify substance must be predicates of some other subject, and nothing can be white which is not also other than white. The Forms we can dispense with, for they are mere sound without sense; and even if there are such things, they are not relevant to our discussion, 35since demonstrations are concerned with predicates such as we have defined.
(3) If A is a quality of B, B cannot be a quality of A-a quality of a quality. Therefore A and B cannot be predicated reciprocally of one another in strict predication: they can be affirmed without falsehood of one another, but not genuinely predicated of each other. For one alternative is that they should be substantially predicated of one another, i.e. B would become the genus or differentia of A-the predicate now become subject. But it has been shown that in these substantial predications neither the ascending predicates nor the descending subjects form an infinite series; e.g. neither the series, man is biped, biped is animal, &c., nor the series predicating animal of man, man of Callias, Callias of a further.
15If we must lay down a rule, let us entitle the latter kind of statement predication, and the former not predication at all, or not strict but accidental predication. 'White' and 'log' will thus serve as types respectively of predicate and subject.
We shall assume, then, that the predicate is invariably predicated 20strictly and not accidentally of the subject, for on such predication demonstrations depend for their force. It follows from this that when a single attribute is predicated of a single subject, the predicate must affirm of the subject either some element constituting its essential nature, or that it is in some way qualified, quantified, essentially related, active, passive, placed, or dated.
(2) Predicates which signify substance signify that the subject is identical with the predicate 25or with a species of the predicate. Predicates not signifying substance which are predicated of a subject not identical with themselves or with a species of themselves are accidental or coincidental; e.g. white is a coincident of man, seeing that man is not identical with white or a species of white, 30but rather with animal, since man is identical with a species of animal. These predicates which do not signify substance must be predicates of some other subject, and nothing can be white which is not also other than white. The Forms we can dispense with, for they are mere sound without sense; and even if there are such things, they are not relevant to our discussion, 35since demonstrations are concerned with predicates such as we have defined.
(3) If A is a quality of B, B cannot be a quality of A-a quality of a quality. Therefore A and B cannot be predicated reciprocally of one another in strict predication: they can be affirmed without falsehood of one another, but not genuinely predicated of each other. For one alternative is that they should be substantially predicated of one another, i.e. B would become the genus or differentia of A-the predicate now become subject. But it has been shown that in these substantial predications neither the ascending predicates nor the descending subjects form an infinite series; e.g. neither the series, man is biped, biped is animal, &c., nor the series predicating animal of man, man of Callias, Callias of a further.
83b
1 οἷον ἢ γένος ὂν ἢ διαφορὰ τοῦ κατηγορουμένου. ταῦτα
δὲ δέδεικται ὅτι οὐκ ἔσται ἄπειρα, οὔτ' ἐπὶ τὸ κάτω οὔτ' ἐπὶ
τὸ ἄνω (οἷον ἄνθρωπος δίπουν, τοῦτο ζῷον, τοῦτο δ' ἕτερον·
οὐδὲ τὸ ζῷον κατ' ἀνθρώπου, τοῦτο δὲ κατὰ Καλλίου, τοῦτο
5 δὲ κατ' ἄλλου ἐν τῷ τί ἐστιν), τὴν μὲν γὰρ οὐσίαν ἅπασαν
ἔστιν ὁρίσασθαι τὴν τοιαύτην, τὰ δ' ἄπειρα οὐκ ἔστι διεξελθεῖν
νοοῦντα. ὥστ' οὔτ' ἐπὶ τὸ ἄνω οὔτ' ἐπὶ τὸ κάτω ἄπειρα·
ἐκείνην γὰρ οὐκ ἔστιν ὁρίσασθαι ἧς τὰ ἄπειρα κατηγορεῖται.
ὡς μὲν δὴ γένη ἀλλήλων οὐκ ἀντικατηγορηθήσεται· ἔσται
10 γὰρ αὐτὸ ὅπερ αὐτό τι. οὐδὲ μὴν τοῦ ποιοῦ ἢ τῶν ἄλλων
οὐδέν, ἂν μὴ κατὰ συμβεβηκὸς κατηγορηθῇ· πάντα γὰρ
ταῦτα συμβέβηκε καὶ κατὰ τῶν οὐσιῶν κατηγορεῖται. ἀλλὰ
δὴ ὅτι οὐδ' εἰς τὸ ἄνω ἄπειρα ἔσται· ἑκάστου γὰρ κατηγορεῖται
ὃ ἂν σημαίνῃ ἢ ποιόν τι ἢ ποσόν τι ἤ τι τῶν τοιούτων
15 ἢ τὰ ἐν τῇ οὐσίᾳ· ταῦτα δὲ πεπέρανται, καὶ τὰ γένη τῶν
κατηγοριῶν πεπέρανται· ἢ γὰρ ποιὸν ἢ ποσὸν ἢ πρός τι ἢ
ποιοῦν ἢ πάσχον ἢ ποὺ ἢ ποτέ. Ὑπόκειται δὴ ἓν καθ' ἑνὸς
κατηγορεῖσθαι, αὐτὰ δὲ αὑτῶν, ὅσα μὴ τί ἐστι, μὴ κατηγορεῖσθαι.
συμβεβηκότα γάρ ἐστι πάντα, ἀλλὰ τὰ μὲν
20 καθ' αὑτά, τὰ δὲ καθ' ἕτερον τρόπον· ταῦτα δὲ πάντα
καθ' ὑποκειμένου τινὸς κατηγορεῖσθαί φαμεν, τὸ δὲ συμβεβηκὸς
οὐκ εἶναι ὑποκείμενόν τι· οὐδὲν γὰρ τῶν τοιούτων τίθεμεν
εἶναι ὃ οὐχ ἕτερόν τι ὂν λέγεται ὃ λέγεται, ἀλλ'
αὐτὸ ἄλλου καὶ τοῦτο καθ' ἑτέρου. οὔτ' εἰς τὸ ἄνω
25 ἄρα ἓν καθ' ἑνὸς οὔτ' εἰς τὸ κάτω ὑπάρχειν λεχθήσεται.
καθ' ὧν μὲν γὰρ λέγεται τὰ συμβεβηκότα, ὅσα ἐν τῇ οὐσίᾳ
ἑκάστου, ταῦτα δὲ οὐκ ἄπειρα· ἄνω δὲ ταῦτά τε καὶ
τὰ συμβεβηκότα, ἀμφότερα οὐκ ἄπειρα. ἀνάγκη ἄρα εἶναί
τι οὗ πρῶτόν τι κατηγορεῖται καὶ τούτου ἄλλο, καὶ τοῦτο
30 ἵστασθαι καὶ εἶναί τι ὃ οὐκέτι οὔτε κατ' ἄλλου προτέρου οὔτε
κατ' ἐκείνου ἄλλο πρότερον κατηγορεῖται.
Εἷς μὲν οὖν τρόπος λέγεται ἀποδείξεως οὗτος, ἔτι δ'
ἄλλος, εἰ ὧν πρότερα ἄττα κατηγορεῖται, ἔστι τούτων ἀπόδειξις,
ὧν δ' ἔστιν ἀπόδειξις, οὔτε βέλτιον ἔχειν ἐγχωρεῖ
35 πρὸς αὐτὰ τοῦ εἰδέναι, οὔτ' εἰδέναι ἄνευ ἀποδείξεως, εἰ δὲ
τόδε διὰ τῶνδε γνώριμον, τάδε δὲ μὴ ἴσμεν μηδὲ βέλτιον
ἔχομεν πρὸς αὐτὰ τοῦ εἰδέναι, οὐδὲ τὸ διὰ τούτων γνώριμον
ἐπιστησόμεθα. εἰ οὖν ἔστι τι εἰδέναι δι' ἀποδείξεως ἁπλῶς
καὶ μὴ ἐκ τινῶν μηδ' ἐξ ὑποθέσεως, ἀνάγκη ἵστασθαι τὰς
1subject as an element of its essential nature, is infinite. For all such substance is definable, and an infinite series cannot be traversed in thought: consequently neither the ascent nor the descent is infinite, since a substance whose predicates were infinite would not be definable. Hence they will not be predicated each as the genus of the other; 10for this would equate a genus with one of its own species. Nor (the other alternative) can a quale be reciprocally predicated of a quale, nor any term belonging to an adjectival category of another such term, except by accidental predication; for all such predicates are coincidents and are predicated of substances. On the other hand-in proof of the impossibility of an infinite ascending series-every predication displays the subject as somehow qualified or quantified or as characterized under one of the other adjectival categories, 15or else is an element in its substantial nature: these latter are limited in number, and the number of the widest kinds under which predications fall is also limited, for every predication must exhibit its subject as somehow qualified, quantified, essentially related, acting or suffering, or in some place or at some time.
I assume first that predication implies a single subject and a single attribute, and secondly that predicates which are not substantial are not predicated of one another. We assume this because such predicates are all coincidents, and 20though some are essential coincidents, others of a different type, yet we maintain that all of them alike are predicated of some substratum and that a coincident is never a substratum-since we do not class as a coincident anything which does not owe its designation to its being something other than itself, but always hold that any coincident is predicated of some substratum other than itself, and that another group of coincidents may have a different substratum. Subject to these assumptions then, neither the ascending 25nor the descending series of predication in which a single attribute is predicated of a single subject is infinite. For the subjects of which coincidents are predicated are as many as the constitutive elements of each individual substance, and these we have seen are not infinite in number, while in the ascending series are contained those constitutive elements with their coincidents-both of which are finite. We conclude that there is a given subject (D) of which some attribute (C) is primarily predicable; that there must be an attribute (B) primarily predicable of the first attribute, 30and that the series must end with a term (A) not predicable of any term prior to the last subject of which it was predicated (B), and of which no term prior to it is predicable.
The argument we have given is one of the so-called proofs; an alternative proof follows. Predicates so related to their subjects that there are other predicates prior to them predicable of those subjects are demonstrable; but of demonstrable propositions one cannot have something better 35than knowledge, nor can one know them without demonstration. Secondly, if a consequent is only known through an antecedent (viz. premisses prior to it) and we neither know this antecedent nor have something better than knowledge of it, then we shall not have scientific knowledge of the consequent.
I assume first that predication implies a single subject and a single attribute, and secondly that predicates which are not substantial are not predicated of one another. We assume this because such predicates are all coincidents, and 20though some are essential coincidents, others of a different type, yet we maintain that all of them alike are predicated of some substratum and that a coincident is never a substratum-since we do not class as a coincident anything which does not owe its designation to its being something other than itself, but always hold that any coincident is predicated of some substratum other than itself, and that another group of coincidents may have a different substratum. Subject to these assumptions then, neither the ascending 25nor the descending series of predication in which a single attribute is predicated of a single subject is infinite. For the subjects of which coincidents are predicated are as many as the constitutive elements of each individual substance, and these we have seen are not infinite in number, while in the ascending series are contained those constitutive elements with their coincidents-both of which are finite. We conclude that there is a given subject (D) of which some attribute (C) is primarily predicable; that there must be an attribute (B) primarily predicable of the first attribute, 30and that the series must end with a term (A) not predicable of any term prior to the last subject of which it was predicated (B), and of which no term prior to it is predicable.
The argument we have given is one of the so-called proofs; an alternative proof follows. Predicates so related to their subjects that there are other predicates prior to them predicable of those subjects are demonstrable; but of demonstrable propositions one cannot have something better 35than knowledge, nor can one know them without demonstration. Secondly, if a consequent is only known through an antecedent (viz. premisses prior to it) and we neither know this antecedent nor have something better than knowledge of it, then we shall not have scientific knowledge of the consequent.
84a
1 κατηγορίας τὰς μεταξύ. εἰ γὰρ μὴ ἵστανται, ἀλλ' ἔστιν ἀεὶ
τοῦ ληφθέντος ἐπάνω, ἁπάντων ἔσται ἀπόδειξις· ὥστ' εἰ τὰ
ἄπειρα μὴ ἐγχωρεῖ διελθεῖν, ὧν ἔστιν ἀπόδειξις, ταῦτ' οὐκ
εἰσόμεθα δι' ἀποδείξεως. εἰ οὖν μηδὲ βέλτιον ἔχομεν πρὸς
5 αὐτὰ τοῦ εἰδέναι, οὐκ ἔσται οὐδὲν ἐπίστασθαι δι' ἀποδείξεως
ἁπλῶς, ἀλλ' ἐξ ὑποθέσεως.
Λογικῶς μὲν οὖν ἐκ τούτων ἄν τις πιστεύσειε περὶ τοῦ
λεχθέντος, ἀναλυτικῶς δὲ διὰ τῶνδε φανερὸν συντομώτερον,
ὅτι οὔτ' ἐπὶ τὸ ἄνω οὔτ' ἐπὶ τὸ κάτω ἄπειρα τὰ κατηγορούμενα
10 ἐνδέχεται εἶναι ἐν ταῖς ἀποδεικτικαῖς ἐπιστήμαις,
περὶ ὧν ἡ σκέψις ἐστίν. ἡ μὲν γὰρ ἀπόδειξίς ἐστι τῶν ὅσα
ὑπάρχει καθ' αὑτὰ τοῖς πράγμασιν. καθ' αὑτὰ δὲ διττῶς·
ὅσα τε γὰρ [ἐν] ἐκείνοις ἐνυπάρχει ἐν τῷ τί ἐστι, καὶ οἷς αὐτὰ
ἐν τῷ τί ἐστιν ὑπάρχουσιν αὐτοῖς· οἷον τῷ ἀριθμῷ τὸ περιττόν,
15 ὃ ὑπάρχει μὲν ἀριθμῷ, ἐνυπάρχει δ' αὐτὸς ὁ ἀριθμὸς
ἐν τῷ λόγῳ αὐτοῦ, καὶ πάλιν πλῆθος ἢ τὸ διαιρετὸν
ἐν τῷ λόγῳ τῷ τοῦ ἀριθμοῦ ἐνυπάρχει. τούτων δ' οὐδέτερα ἐνδέχεται
ἄπειρα εἶναι, οὔθ' ὡς τὸ περιττὸν τοῦ ἀριθμοῦ (πάλιν
γὰρ ἂν τῷ περιττῷ ἄλλο εἴη ᾧ ἐνυπῆρχεν ὑπάρχοντι·
20 τοῦτο δ' εἰ ἔστι, πρῶτον ὁ ἀριθμὸς ἐνυπάρξει ὑπάρχουσιν
αὐτῷ· εἰ οὖν μὴ ἐνδέχεται ἄπειρα τοιαῦτα ὑπάρχειν
ἐν τῷ ἑνί, οὐδ' ἐπὶ τὸ ἄνω ἔσται ἄπειρα· ἀλλὰ μὴν
ἀνάγκη γε πάντα ὑπάρχειν τῷ πρώτῳ, οἷον τῷ ἀριθμῷ,
κἀκείνοις τὸν ἀριθμόν, ὥστ' ἀντιστρέφοντα ἔσται, ἀλλ' οὐχ
25 ὑπερτείνοντα)· οὐδὲ μὴν ὅσα ἐν τῷ τί ἐστιν ἐνυπάρχει, οὐδὲ
ταῦτα ἄπειρα· οὐδὲ γὰρ ἂν εἴη ὁρίσασθαι. ὥστ' εἰ τὰ μὲν
κατηγορούμενα καθ' αὑτὰ πάντα λέγεται, ταῦτα δὲ μὴ
ἄπειρα, ἵσταιτο ἂν τὰ ἐπὶ τὸ ἄνω, ὥστε καὶ ἐπὶ τὸ κάτω.
Εἰ δ' οὕτω, καὶ τὰ ἐν τῷ μεταξὺ δύο ὅρων ἀεὶ πεπερασμένα.
30 εἰ δὲ τοῦτο, δῆλον ἤδη καὶ τῶν ἀποδείξεων ὅτι
ἀνάγκη ἀρχάς τε εἶναι, καὶ μὴ πάντων εἶναι ἀπόδειξιν,
ὅπερ ἔφαμέν τινας λέγειν κατ' ἀρχάς. εἰ γὰρ εἰσὶν ἀρχαί,
οὔτε πάντ' ἀποδεικτὰ οὔτ' εἰς ἄπειρον οἷόν τε βαδίζειν· τὸ
γὰρ εἶναι τούτων ὁποτερονοῦν οὐδὲν ἄλλο ἐστὶν ἢ τὸ εἶναι μηδὲν
35 διάστημα ἄμεσον καὶ ἀδιαίρετον, ἀλλὰ πάντα διαιρετά.
τῷ γὰρ ἐντὸς ἐμβάλλεσθαι ὅρον, ἀλλ' οὐ τῷ προσλαμβάνεσθαι
ἀποδείκνυται τὸ ἀποδεικνύμενον, ὥστ' εἰ τοῦτ' εἰς
ἄπειρον ἐνδέχεται ἰέναι, ἐνδέχοιτ' ἂν δύο ὅρων ἄπειρα μεταξὺ
εἶναι μέσα. ἀλλὰ τοῦτ' ἀδύνατον, εἰ ἵστανται αἱ κατηγορίαι
1Therefore, if it is possible through demonstration to know anything without qualification and not merely as dependent on the acceptance of certain premisses-i.e. hypothetically-the series of intermediate predications must terminate. If it does not terminate, and beyond any predicate taken as higher than another there remains another still higher, then every predicate is demonstrable. Consequently, since these demonstrable predicates are infinite in number and therefore cannot be traversed, we shall not know them by demonstration. If, therefore, we have not something better than knowledge of them, 5we cannot through demonstration have unqualified but only hypothetical science of anything.
As dialectical proofs of our contention these may carry conviction, but an analytic process will show more briefly that neither the ascent nor the descent of predication can be infinite 10in the demonstrative sciences which are the object of our investigation. Demonstration proves the inherence of essential attributes in things. Now attributes may be essential for two reasons: either because they are elements in the essential nature of their subjects, or because their subjects are elements in their essential nature. An example of the latter is odd as an attribute of number-15though it is number's attribute, yet number itself is an element in the definition of odd; of the former, multiplicity or the indivisible, which are elements in the definition of number. In neither kind of attribution can the terms be infinite. They are not infinite where each is related to the term below it as odd is to number, for this would mean the inherence in odd of another attribute of odd in whose nature odd was an essential element: 20but then number will be an ultimate subject of the whole infinite chain of attributes, and be an element in the definition of each of them. Hence, since an infinity of attributes such as contain their subject in their definition cannot inhere in a single thing, the ascending series is equally finite. Note, moreover, that all such attributes must so inhere in the ultimate subject-e.g. its attributes in number and number in them-as to be commensurate with the subject and not of wider extent. 25Attributes which are essential elements in the nature of their subjects are equally finite: otherwise definition would be impossible. Hence, if all the attributes predicated are essential and these cannot be infinite, the ascending series will terminate, and consequently the descending series too.
If this is so, it follows that the intermediates between any two terms are also always limited in number. 30An immediately obvious consequence of this is that demonstrations necessarily involve basic truths, and that the contention of some-referred to at the outset-that all truths are demonstrable is mistaken. For if there are basic truths, (a) not all truths are demonstrable, and (b) an infinite regress is impossible; since if either (a) or (b) were not a fact, it would mean that 35no interval was immediate and indivisible, but that all intervals were divisible. This is true because a conclusion is demonstrated by the interposition, not the apposition, of a fresh term.
As dialectical proofs of our contention these may carry conviction, but an analytic process will show more briefly that neither the ascent nor the descent of predication can be infinite 10in the demonstrative sciences which are the object of our investigation. Demonstration proves the inherence of essential attributes in things. Now attributes may be essential for two reasons: either because they are elements in the essential nature of their subjects, or because their subjects are elements in their essential nature. An example of the latter is odd as an attribute of number-15though it is number's attribute, yet number itself is an element in the definition of odd; of the former, multiplicity or the indivisible, which are elements in the definition of number. In neither kind of attribution can the terms be infinite. They are not infinite where each is related to the term below it as odd is to number, for this would mean the inherence in odd of another attribute of odd in whose nature odd was an essential element: 20but then number will be an ultimate subject of the whole infinite chain of attributes, and be an element in the definition of each of them. Hence, since an infinity of attributes such as contain their subject in their definition cannot inhere in a single thing, the ascending series is equally finite. Note, moreover, that all such attributes must so inhere in the ultimate subject-e.g. its attributes in number and number in them-as to be commensurate with the subject and not of wider extent. 25Attributes which are essential elements in the nature of their subjects are equally finite: otherwise definition would be impossible. Hence, if all the attributes predicated are essential and these cannot be infinite, the ascending series will terminate, and consequently the descending series too.
If this is so, it follows that the intermediates between any two terms are also always limited in number. 30An immediately obvious consequence of this is that demonstrations necessarily involve basic truths, and that the contention of some-referred to at the outset-that all truths are demonstrable is mistaken. For if there are basic truths, (a) not all truths are demonstrable, and (b) an infinite regress is impossible; since if either (a) or (b) were not a fact, it would mean that 35no interval was immediate and indivisible, but that all intervals were divisible. This is true because a conclusion is demonstrated by the interposition, not the apposition, of a fresh term.
84b
1 ἐπὶ τὸ ἄνω καὶ τὸ κάτω. ὅτι δὲ ἵστανται, δέδεικται
λογικῶς μὲν πρότερον, ἀναλυτικῶς δὲ νῦν.
1If such interposition could continue to infinity there might be an infinite number of terms between any two terms; but this is impossible if both the ascending and descending series of predication terminate; and of this fact, which before was shown dialectically, analytic proof has now been given.
Book 1,Chapter 23 (84b3–85a12)
Δεδειγμένων δὲ τούτων φανερὸν ὅτι, ἐάν τι τὸ αὐτὸ
δυσὶν ὑπάρχῃ, οἷον τὸ Α τῷ τε Γ καὶ τῷ Δ, μὴ κατηγορουμένου
5 θατέρου κατὰ θατέρου, ἢ μηδαμῶς ἢ μὴ κατὰ
παντός, ὅτι οὐκ ἀεὶ κατὰ κοινόν τι ὑπάρξει. οἷον τῷ ἰσοσκελεῖ
καὶ τῷ σκαληνεῖ τὸ δυσὶν ὀρθαῖς ἴσας ἔχειν κατὰ
κοινόν τι ὑπάρχει (ᾗ γὰρ σχῆμά τι, ὑπάρχει, καὶ οὐχ
ᾗ ἕτερον), τοῦτο δ' οὐκ ἀεὶ οὕτως ἔχει. ἔστω γὰρ τὸ Β καθ'
10 ὃ τὸ Α τῷ Γ Δ ὑπάρχει. δῆλον τοίνυν ὅτι καὶ τὸ Β τῷ
Γ καὶ Δ κατ' ἄλλο κοινόν, κἀκεῖνο καθ' ἕτερον, ὥστε
δύο ὅρων μεταξὺ ἄπειροι ἂν ἐμπίπτοιεν ὅροι. ἀλλ' ἀδύνατον.
κατὰ μὲν τοίνυν κοινόν τι ὑπάρχειν οὐκ ἀνάγκη ἀεὶ
τὸ αὐτὸ πλείοσιν, εἴπερ ἔσται ἄμεσα διαστήματα. ἐν μέντοι
15 τῷ αὐτῷ γένει καὶ ἐκ τῶν αὐτῶν ἀτόμων ἀνάγκη τοὺς
ὅρους εἶναι, εἴπερ τῶν καθ' αὑτὸ ὑπαρχόντων ἔσται τὸ κοινόν·
οὐ γὰρ ἦν ἐξ ἄλλου γένους εἰς ἄλλο διαβῆναι τὰ δεικνύμενα.
Φανερὸν δὲ καὶ ὅτι, ὅταν τὸ Α τῷ Β ὑπάρχῃ, εἰ
20 μὲν ἔστι τι μέσον, ἔστι δεῖξαι ὅτι τὸ Α τῷ Β ὑπάρχει, καὶ
στοιχεῖα τούτου ἔστι ταὐτὰ καὶ τοσαῦθ' ὅσα μέσα ἐστίν· αἱ
γὰρ ἄμεσοι προτάσεις στοιχεῖα, ἢ πᾶσαι ἢ αἱ καθόλου. εἰ
δὲ μὴ ἔστιν, οὐκέτι ἔστιν ἀπόδειξις, ἀλλ' ἡ ἐπὶ τὰς ἀρχὰς
ὁδὸς αὕτη ἐστίν. ὁμοίως δὲ καὶ εἰ τὸ Α τῷ Β μὴ ὑπάρχει,
25 εἰ μὲν ἔστιν ἢ μέσον ἢ πρότερον ᾧ οὐχ ὑπάρχει, ἔστιν ἀπόδειξις,
εἰ δὲ μή, οὐκ ἔστιν, ἀλλ' ἀρχή, καὶ στοιχεῖα τοσαῦτ'
ἔστιν ὅσοι ὅροι· αἱ γὰρ τούτων προτάσεις ἀρχαὶ τῆς ἀποδείξεώς
εἰσιν. καὶ ὥσπερ ἔνιαι ἀρχαί εἰσιν ἀναπόδεικτοι, ὅτι
ἐστὶ τόδε τοδὶ καὶ ὑπάρχει τόδε τῳδί, οὕτω καὶ ὅτι οὐκ ἔστι
30 τόδε τοδὶ οὐδ' ὑπάρχει τόδε τῳδί, ὥσθ' αἱ μὲν εἶναί τι, αἱ
δὲ μὴ εἶναί τι ἔσονται ἀρχαί. Ὅταν δὲ δέῃ δεῖξαι, ληπτέον
ὃ τοῦ Β πρῶτον κατηγορεῖται. ἔστω τὸ Γ, καὶ τούτου ὁμοίως
τὸ Δ. καὶ οὕτως ἀεὶ βαδίζοντι οὐδέποτ' ἐξωτέρω πρότασις
οὐδ' ὑπάρχον λαμβάνεται τοῦ Α ἐν τῷ δεικνύναι, ἀλλ' ἀεὶ
35 τὸ μέσον πυκνοῦται, ἕως ἀδιαίρετα γένηται καὶ ἕν. ἔστι δ'
ἓν ὅταν ἄμεσον γένηται, καὶ μία πρότασις ἁπλῶς ἡ ἄμεσος.
καὶ ὥσπερ ἐν τοῖς ἄλλοις ἡ ἀρχὴ ἁπλοῦν, τοῦτο δ'
οὐ ταὐτὸ πανταχοῦ, ἀλλ' ἐν βάρει μὲν μνᾶ, ἐν δὲ μέλει
δίεσις, ἄλλο δ' ἐν ἄλλῳ, οὕτως ἐν συλλογισμῷ τὸ ἓν
3It is an evident corollary of these conclusions that if the same attribute A inheres in two terms C and D 5predicable either not at all, or not of all instances, of one another, it does not always belong to them in virtue of a common middle term. Isosceles and scalene possess the attribute of having their angles equal to two right angles in virtue of a common middle; for they possess it in so far as they are both a certain kind of figure, and not in so far as they differ from one another. But this is not always the case: for, were it so, if we take B as the common middle 10in virtue of which A inheres in C and D, clearly B would inhere in C and D through a second common middle, and this in turn would inhere in C and D through a third, so that between two terms an infinity of intermediates would fall-an impossibility. Thus it need not always be in virtue of a common middle term that a single attribute inheres in several subjects, since there must be immediate intervals. Yet if the attribute to be proved common to two subjects is to be one of their essential attributes, the middle terms involved must be 15within one subject genus and be derived from the same group of immediate premisses; for we have seen that processes of proof cannot pass from one genus to another.
It is also clear that when A inheres in B, 20this can be demonstrated if there is a middle term. Further, the 'elements' of such a conclusion are the premisses containing the middle in question, and they are identical in number with the middle terms, seeing that the immediate propositions-or at least such immediate propositions as are universal-are the 'elements'. If, on the other hand, there is no middle term, demonstration ceases to be possible: we are on the way to the basic truths. Similarly if A does not inhere in B, 25this can be demonstrated if there is a middle term or a term prior to B in which A does not inhere: otherwise there is no demonstration and a basic truth is reached. There are, moreover, as many 'elements' of the demonstrated conclusion as there are middle terms, since it is propositions containing these middle terms that are the basic premisses on which the demonstration rests; and as there are some indemonstrable basic truths asserting that 'this is that' or that 'this inheres in that', 30so there are others denying that 'this is that' or that 'this inheres in that'-in fact some basic truths will affirm and some will deny being.
When we are to prove a conclusion, we must take a primary essential predicate-suppose it C-of the subject B, and then suppose A similarly predicable of C. If we proceed in this manner, no proposition or attribute which falls beyond A is admitted in the proof: 35the interval is constantly condensed until subject and predicate become indivisible, i.e. one. We have our unit when the premiss becomes immediate, since the immediate premiss alone is a single premiss in the unqualified sense of 'single'.
It is also clear that when A inheres in B, 20this can be demonstrated if there is a middle term. Further, the 'elements' of such a conclusion are the premisses containing the middle in question, and they are identical in number with the middle terms, seeing that the immediate propositions-or at least such immediate propositions as are universal-are the 'elements'. If, on the other hand, there is no middle term, demonstration ceases to be possible: we are on the way to the basic truths. Similarly if A does not inhere in B, 25this can be demonstrated if there is a middle term or a term prior to B in which A does not inhere: otherwise there is no demonstration and a basic truth is reached. There are, moreover, as many 'elements' of the demonstrated conclusion as there are middle terms, since it is propositions containing these middle terms that are the basic premisses on which the demonstration rests; and as there are some indemonstrable basic truths asserting that 'this is that' or that 'this inheres in that', 30so there are others denying that 'this is that' or that 'this inheres in that'-in fact some basic truths will affirm and some will deny being.
When we are to prove a conclusion, we must take a primary essential predicate-suppose it C-of the subject B, and then suppose A similarly predicable of C. If we proceed in this manner, no proposition or attribute which falls beyond A is admitted in the proof: 35the interval is constantly condensed until subject and predicate become indivisible, i.e. one. We have our unit when the premiss becomes immediate, since the immediate premiss alone is a single premiss in the unqualified sense of 'single'.
85a
1 πρότασις ἄμεσος, ἐν δ' ἀποδείξει καὶ ἐπιστήμῃ ὁ νοῦς. ἐν
μὲν οὖν τοῖς δεικτικοῖς συλλογισμοῖς τοῦ ὑπάρχοντος οὐδὲν ἔξω
πίπτει, ἐν δὲ τοῖς στερητικοῖς, ἔνθα μὲν ὃ δεῖ ὑπάρχειν,
οὐδὲν τούτου ἔξω πίπτει, οἷον εἰ τὸ Α τῷ Β διὰ τοῦ Γ μή
5 (εἰ γὰρ τῷ μὲν Β παντὶ τὸ Γ, τῷ δὲ Γ μηδενὶ τὸ Α)· πάλιν
ἂν δέῃ ὅτι τῷ Γ τὸ Α οὐδενὶ ὑπάρχει, μέσον ληπτέον
τοῦ Α καὶ Γ, καὶ οὕτως ἀεὶ πορεύσεται. ἐὰν δὲ δέῃ δεῖξαι
ὅτι τὸ Δ τῷ Ε οὐχ ὑπάρχει τῷ τὸ Γ τῷ μὲν Δ παντὶ
ὑπάρχειν, τῷ δὲ Ε μηδενί [ἢ μὴ παντί], τοῦ Ε οὐδέποτ' ἔξω
10 πεσεῖται· τοῦτο δ' ἐστὶν ᾧ δεῖ ὑπάρχειν. ἐπὶ δὲ τοῦ τρίτου
τρόπου, οὔτε ἀφ' οὗ δεῖ οὔτε ὃ δεῖ στερῆσαι οὐδέποτ' ἔξω
βαδιεῖται.
1And as in other spheres the basic element is simple but not identical in all-in a system of weight it is the mina, in music the quarter-tone, and so on--so in syllogism the unit is an immediate premiss, and in the knowledge that demonstration gives it is an intuition. In syllogisms, then, which prove the inherence of an attribute, nothing falls outside the major term. In the case of negative syllogisms on the other hand, (1) in the first figure nothing falls outside the major term whose inherence is in question; e.g. to prove through a middle C that A does not inhere in B 5the premisses required are, all B is C, no C is A. Then if it has to be proved that no C is A, a middle must be found between and C; and this procedure will never vary.
(2) If we have to show that E is not D by means of the premisses, all D is C; no E, or not all E, is C; then the middle will never 10fall beyond E, and E is the subject of which D is to be denied in the conclusion.
(3) In the third figure the middle will never fall beyond the limits of the subject and the attribute denied of it.
(2) If we have to show that E is not D by means of the premisses, all D is C; no E, or not all E, is C; then the middle will never 10fall beyond E, and E is the subject of which D is to be denied in the conclusion.
(3) In the third figure the middle will never fall beyond the limits of the subject and the attribute denied of it.
Book 1,Chapter 24 (85a13–86a30)
Οὔσης δ' ἀποδείξεως τῆς μὲν καθόλου τῆς δὲ κατὰ
μέρος, καὶ τῆς μὲν κατηγορικῆς τῆς δὲ στερητικῆς, ἀμφισβητεῖται
15 ποτέρα βελτίων· ὡς δ' αὔτως καὶ περὶ τῆς ἀποδεικνύναι
λεγομένης καὶ τῆς εἰς τὸ ἀδύνατον ἀγούσης ἀποδείξεως.
πρῶτον μὲν οὖν ἐπισκεψώμεθα περὶ τῆς καθόλου
καὶ τῆς κατὰ μέρος· δηλώσαντες δὲ τοῦτο, καὶ περὶ τῆς
δεικνύναι λεγομένης καὶ τῆς εἰς τὸ ἀδύνατον εἴπωμεν.
20 Δόξειε μὲν οὖν τάχ' ἄν τισιν ὡδὶ σκοποῦσιν ἡ κατὰ
μέρος εἶναι βελτίων. εἰ γὰρ καθ' ἣν μᾶλλον ἐπιστάμεθα
ἀπόδειξιν βελτίων ἀπόδειξις (αὕτη γὰρ ἀρετὴ ἀποδείξεως),
μᾶλλον δ' ἐπιστάμεθα ἕκαστον ὅταν αὐτὸ εἰδῶμεν καθ'
αὑτὸ ἢ ὅταν κατ' ἄλλο (οἷον τὸν μουσικὸν Κορίσκον ὅταν
25 ὅτι ὁ Κορίσκος μουσικὸς ἢ ὅταν ὅτι ἅνθρωπος μουσικός·
ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων), ἡ δὲ καθόλου ὅτι ἄλλο, οὐχ
ὅτι αὐτὸ τετύχηκεν ἐπιδείκνυσιν (οἷον ὅτι τὸ ἰσοσκελὲς οὐχ ὅτι
ἰσοσκελὲς ἀλλ' ὅτι τρίγωνον), ἡ δὲ κατὰ μέρος ὅτι αὐτό· —εἰ
δὴ βελτίων μὲν ἡ καθ' αὑτό, τοιαύτη δ' ἡ κατὰ μέρος τῆς
30 καθόλου μᾶλλον, καὶ βελτίων ἂν ἡ κατὰ μέρος ἀπόδειξις
εἴη. ἔτι εἰ τὸ μὲν καθόλου μὴ ἔστι τι παρὰ τὰ καθ' ἕκαστα,
ἡ δ' ἀπόδειξις δόξαν ἐμποιεῖ εἶναί τι τοῦτο καθ' ὃ ἀποδείκνυσι,
καί τινα φύσιν ὑπάρχειν ἐν τοῖς οὖσι ταύτην, οἷον
τριγώνου παρὰ τὰ τινὰ καὶ σχήματος παρὰ τὰ τινὰ καὶ
35 ἀριθμοῦ παρὰ τοὺς τινὰς ἀριθμούς, βελτίων δ' ἡ περὶ ὄντος
ἢ μὴ ὄντος καὶ δι' ἣν μὴ ἀπατηθήσεται ἢ δι' ἥν, ἔστι
δ' ἡ μὲν καθόλου τοιαύτη (προϊόντες γὰρ δεικνύουσιν ὥσπερ
περὶ τοῦ ἀνὰ λόγον, οἷον ὅτι ὃ ἂν ᾖ τι τοιοῦτον ἔσται ἀνὰ
λόγον ὃ οὔτε γραμμὴ οὔτ' ἀριθμὸς οὔτε στερεὸν οὔτ' ἐπίπεδον,
13Since demonstrations may be either commensurately universal or particular, and either affirmative or negative; the question arises, 15which form is the better? And the same question may be put in regard to so-called 'direct' demonstration and reductio ad impossibile. Let us first examine the commensurately universal and the particular forms, and when we have cleared up this problem proceed to discuss 'direct' demonstration and reductio ad impossibile.
20The following considerations might lead some minds to prefer particular demonstration.
(1) The superior demonstration is the demonstration which gives us greater knowledge (for this is the ideal of demonstration), and we have greater knowledge of a particular individual when we know it in itself than when we know it through something else; e.g. we know Coriscus the musician better when 25we know that Coriscus is musical than when we know only that man is musical, and a like argument holds in all other cases. But commensurately universal demonstration, instead of proving that the subject itself actually is x, proves only that something else is x- e.g. in attempting to prove that isosceles is x, it proves not that isosceles but only that triangle is x- whereas particular demonstration proves that the subject itself is x. The demonstration, then, that a subject, as such, possesses an attribute is superior. If this is so, and if the particular rather 30than the commensurately universal forms demonstrates, particular demonstration is superior.
(2) The universal has not a separate being over against groups of singulars. Demonstration nevertheless creates the opinion that its function is conditioned by something like this-some separate entity belonging to the real world; that, for instance, of triangle or of figure or number, over against particular triangles, figures, and 35numbers. But demonstration which touches the real and will not mislead is superior to that which moves among unrealities and is delusory. Now commensurately universal demonstration is of the latter kind: if we engage in it we find ourselves reasoning after a fashion well illustrated by the argument that the proportionate is what answers to the definition of some entity which is neither line, number, solid, nor plane, but a proportionate apart from all these. Since, then, such a proof is characteristically commensurate and universal, and less touches reality than does particular demonstration, and creates a false opinion, it will follow that commensurate and universal is inferior to particular demonstration.
20The following considerations might lead some minds to prefer particular demonstration.
(1) The superior demonstration is the demonstration which gives us greater knowledge (for this is the ideal of demonstration), and we have greater knowledge of a particular individual when we know it in itself than when we know it through something else; e.g. we know Coriscus the musician better when 25we know that Coriscus is musical than when we know only that man is musical, and a like argument holds in all other cases. But commensurately universal demonstration, instead of proving that the subject itself actually is x, proves only that something else is x- e.g. in attempting to prove that isosceles is x, it proves not that isosceles but only that triangle is x- whereas particular demonstration proves that the subject itself is x. The demonstration, then, that a subject, as such, possesses an attribute is superior. If this is so, and if the particular rather 30than the commensurately universal forms demonstrates, particular demonstration is superior.
(2) The universal has not a separate being over against groups of singulars. Demonstration nevertheless creates the opinion that its function is conditioned by something like this-some separate entity belonging to the real world; that, for instance, of triangle or of figure or number, over against particular triangles, figures, and 35numbers. But demonstration which touches the real and will not mislead is superior to that which moves among unrealities and is delusory. Now commensurately universal demonstration is of the latter kind: if we engage in it we find ourselves reasoning after a fashion well illustrated by the argument that the proportionate is what answers to the definition of some entity which is neither line, number, solid, nor plane, but a proportionate apart from all these. Since, then, such a proof is characteristically commensurate and universal, and less touches reality than does particular demonstration, and creates a false opinion, it will follow that commensurate and universal is inferior to particular demonstration.
85b
1 ἀλλὰ παρὰ ταῦτά τι)· —εἰ οὖν καθόλου μὲν μᾶλλον
αὕτη, περὶ ὄντος δ' ἧττον τῆς κατὰ μέρος καὶ ἐμποιεῖ δόξαν
ψευδῆ, χείρων ἂν εἴη ἡ καθόλου τῆς κατὰ μέρος.
Ἢ πρῶτον μὲν οὐδὲν μᾶλλον ἐπὶ τοῦ καθόλου ἢ τοῦ κατὰ
5 μέρος ἅτερος λόγος ἐστίν; εἰ γὰρ τὸ δυσὶν ὀρθαῖς ὑπάρχει
μὴ ᾗ ἰσοσκελὲς ἀλλ' ᾗ τρίγωνον, ὁ εἰδὼς ὅτι ἰσοσκελὲς ἧττον
οἶδεν ᾗ αὐτὸ ἢ ὁ εἰδὼς ὅτι τρίγωνον. ὅλως τε, εἰ μὲν μὴ
ὄντος ᾗ τρίγωνον εἶτα δείκνυσιν, οὐκ ἂν εἴη ἀπόδειξις, εἰ δὲ
ὄντος, ὁ εἰδὼς ἕκαστον ᾗ ἕκαστον ὑπάρχει μᾶλλον οἶδεν. εἰ δὴ
10 τὸ τρίγωνον ἐπὶ πλέον ἐστί, καὶ ὁ αὐτὸς λόγος, καὶ μὴ καθ'
ὁμωνυμίαν τὸ τρίγωνον, καὶ ὑπάρχει παντὶ τριγώνῳ τὸ δύο,
οὐκ ἂν τὸ τρίγωνον ᾗ ἰσοσκελές, ἀλλὰ τὸ ἰσοσκελὲς ᾗ τρίγωνον,
ἔχοι τοιαύτας τὰς γωνίας. ὥστε ὁ καθόλου εἰδὼς μᾶλλον
οἶδεν ᾗ ὑπάρχει ἢ ὁ κατὰ μέρος. βελτίων ἄρα ἡ καθόλου
15 τῆς κατὰ μέρος. ἔτι εἰ μὲν εἴη τις λόγος εἷς καὶ μὴ
ὁμωνυμία τὸ καθόλου, εἴη τ' ἂν οὐδὲν ἧττον ἐνίων τῶν κατὰ
μέρος, ἀλλὰ καὶ μᾶλλον, ὅσῳ τὰ ἄφθαρτα ἐν ἐκείνοις
ἐστί, τὰ δὲ κατὰ μέρος φθαρτὰ μᾶλλον, ἔτι τε οὐδεμία
ἀνάγκη ὑπολαμβάνειν τι εἶναι τοῦτο παρὰ ταῦτα, ὅτι ἓν δηλοῖ,
20 οὐδὲν μᾶλλον ἢ ἐπὶ τῶν ἄλλων ὅσα μὴ τὶ σημαίνει
ἀλλ' ἢ ποιὸν ἢ πρός τι ἢ ποιεῖν. εἰ δὲ ἄρα, οὐχ ἡ ἀπόδειξις
αἰτία ἀλλ' ὁ ἀκούων.
Ἔτι εἰ ἡ ἀπόδειξις μέν ἐστι συλλογισμὸς δεικτικὸς αἰτίας
καὶ τοῦ διὰ τί, τὸ καθόλου δ' αἰτιώτερον (ᾧ γὰρ καθ'
25 αὑτὸ ὑπάρχει τι, τοῦτο αὐτὸ αὑτῷ αἴτιον· τὸ δὲ καθόλου
πρῶτον· αἴτιον ἄρα τὸ καθόλου)· ὥστε καὶ ἡ ἀπόδειξις βελτίων·
μᾶλλον γὰρ τοῦ αἰτίου καὶ τοῦ διὰ τί ἐστιν. Ἔτι μέχρι
τούτου ζητοῦμεν τὸ διὰ τί, καὶ τότε οἰόμεθα εἰδέναι, ὅταν
μὴ ᾖ ὅτι τι ἄλλο τοῦτο ἢ γινόμενον ἢ ὄν· τέλος γὰρ καὶ
30 πέρας τὸ ἔσχατον ἤδη οὕτως ἐστίν. οἷον τίνος ἕνεκα ἦλθεν;
ὅπως λάβῃ τἀργύριον, τοῦτο δ' ὅπως ἀποδῷ ὃ ὤφειλε, τοῦτο
δ' ὅπως μὴ ἀδικήσῃ· καὶ οὕτως ἰόντες, ὅταν μηκέτι δι'
ἄλλο μηδ' ἄλλου ἕνεκα, διὰ τοῦτο ὡς τέλος φαμὲν ἐλθεῖν
καὶ εἶναι καὶ γίνεσθαι, καὶ τότε εἰδέναι μάλιστα διὰ τί
35 ἦλθεν. εἰ δὴ ὁμοίως ἔχει ἐπὶ πασῶν τῶν αἰτιῶν καὶ τῶν διὰ
τί, ἐπὶ δὲ τῶν ὅσα αἴτια οὕτως ὡς οὗ ἕνεκα οὕτως ἴσμεν
μάλιστα, καὶ ἐπὶ τῶν ἄλλων ἄρα τότε μάλιστα ἴσμεν, ὅταν
μηκέτι ὑπάρχῃ τοῦτο ὅτι ἄλλο. ὅταν μὲν οὖν γινώσκωμεν
ὅτι τέτταρσιν αἱ ἔξω ἴσαι ὅτι ἰσοσκελές, ἔτι λείπεται διὰ
1We may retort thus. (1) The first argument applies no more to commensurate and universal 5than to particular demonstration. If equality to two right angles is attributable to its subject not qua isosceles but qua triangle, he who knows that isosceles possesses that attribute knows the subject as qua itself possessing the attribute, to a less degree than he who knows that triangle has that attribute. To sum up the whole matter: if a subject is proved to possess qua triangle an attribute which it does not in fact possess qua triangle, that is not demonstration: but if it does possess it qua triangle the rule applies that the greater knowledge is his who knows the subject as possessing its attribute qua that in virtue of which it actually does possess it. Since, then, 10triangle is the wider term, and there is one identical definition of triangle-i.e. the term is not equivocal-and since equality to two right angles belongs to all triangles, it is isosceles qua triangle and not triangle qua isosceles which has its angles so related. It follows that he who knows a connexion universally has greater knowledge of it as it in fact is than he who knows the particular; and the inference is that commensurate and universal 15is superior to particular demonstration.
(2) If there is a single identical definition i.e. if the commensurate universal is unequivocal-then the universal will possess being not less but more than some of the particulars, inasmuch as it is universals which comprise the imperishable, particulars that tend to perish.
(3) Because the universal has a single meaning, we are not therefore compelled to suppose that in these examples it has being as a substance apart from its particulars-20any more than we need make a similar supposition in the other cases of unequivocal universal predication, viz. where the predicate signifies not substance but quality, essential relatedness, or action. If such a supposition is entertained, the blame rests not with the demonstration but with the hearer.
(4) Demonstration is syllogism that proves the cause, i.e. the reasoned fact, and it is rather the commensurate universal than the particular which is causative (as may be shown thus: that which possesses an attribute through its own essential nature 25is itself the cause of the inherence, and the commensurate universal is primary; hence the commensurate universal is the cause). Consequently commensurately universal demonstration is superior as more especially proving the cause, that is the reasoned fact.
(5) Our search for the reason ceases, and we think that we know, when the coming to be or existence of the fact before us is not due to the coming to be or existence of some other fact, for the last step of a search thus conducted is eo ipso the end 30and limit of the problem. Thus: 'Why did he come?' 'To get the money-wherewith to pay a debt-that he might thereby do what was right.' When in this regress we can no longer find an efficient or final cause, we regard the last step of it as the end of the coming-or being or coming to be-and we regard ourselves as then only having full knowledge of the reason why he came.
If, then, all causes and reasons are alike in this respect, and if this is the means to full knowledge in the case of final causes such as we have exemplified, it follows 35that in the case of the other causes also full knowledge is attained when an attribute no longer inheres because of something else. Thus, when we learn that exterior angles are equal to four right angles because they are the exterior angles of an isosceles, there still remains the question 'Why has isosceles this attribute?' and its answer 'Because it is a triangle, and a triangle has it because a triangle is a rectilinear figure.'
(2) If there is a single identical definition i.e. if the commensurate universal is unequivocal-then the universal will possess being not less but more than some of the particulars, inasmuch as it is universals which comprise the imperishable, particulars that tend to perish.
(3) Because the universal has a single meaning, we are not therefore compelled to suppose that in these examples it has being as a substance apart from its particulars-20any more than we need make a similar supposition in the other cases of unequivocal universal predication, viz. where the predicate signifies not substance but quality, essential relatedness, or action. If such a supposition is entertained, the blame rests not with the demonstration but with the hearer.
(4) Demonstration is syllogism that proves the cause, i.e. the reasoned fact, and it is rather the commensurate universal than the particular which is causative (as may be shown thus: that which possesses an attribute through its own essential nature 25is itself the cause of the inherence, and the commensurate universal is primary; hence the commensurate universal is the cause). Consequently commensurately universal demonstration is superior as more especially proving the cause, that is the reasoned fact.
(5) Our search for the reason ceases, and we think that we know, when the coming to be or existence of the fact before us is not due to the coming to be or existence of some other fact, for the last step of a search thus conducted is eo ipso the end 30and limit of the problem. Thus: 'Why did he come?' 'To get the money-wherewith to pay a debt-that he might thereby do what was right.' When in this regress we can no longer find an efficient or final cause, we regard the last step of it as the end of the coming-or being or coming to be-and we regard ourselves as then only having full knowledge of the reason why he came.
If, then, all causes and reasons are alike in this respect, and if this is the means to full knowledge in the case of final causes such as we have exemplified, it follows 35that in the case of the other causes also full knowledge is attained when an attribute no longer inheres because of something else. Thus, when we learn that exterior angles are equal to four right angles because they are the exterior angles of an isosceles, there still remains the question 'Why has isosceles this attribute?' and its answer 'Because it is a triangle, and a triangle has it because a triangle is a rectilinear figure.'
86a
1 τί τὸ ἰσοσκελές—ὅτι τρίγωνον, καὶ τοῦτο, ὅτι σχῆμα εὐθύγραμμον.
εἰ δὲ τοῦτο μηκέτι διότι ἄλλο, τότε μάλιστα
ἴσμεν. καὶ καθόλου δὲ τότε· ἡ καθόλου ἄρα βελτίων. Ἔτι
ὅσῳ ἂν μᾶλλον κατὰ μέρος ᾖ, εἰς τὰ ἄπειρα ἐμπίπτει, ἡ
5 δὲ καθόλου εἰς τὸ ἁπλοῦν καὶ τὸ πέρας. ἔστι δ', ᾗ μὲν
ἄπειρα, οὐκ ἐπιστητά, ᾗ δὲ πεπέρανται, ἐπιστητά. ᾗ ἄρα καθόλου,
μᾶλλον ἐπιστητὰ ἢ ᾗ κατὰ μέρος. ἀποδεικτὰ ἄρα
μᾶλλον τὰ καθόλου. τῶν δ' ἀποδεικτῶν μᾶλλον μᾶλλον
ἀπόδειξις· ἅμα γὰρ μᾶλλον τὰ πρός τι. βελτίων ἄρα ἡ
10 καθόλου, ἐπείπερ καὶ μᾶλλον ἀπόδειξις. Ἔτι εἰ αἱρετωτέρα καθ'
ἣν τοῦτο καὶ ἄλλο ἢ καθ' ἣν τοῦτο μόνον οἶδεν· ὁ δὲ τὴν
καθόλου ἔχων οἶδε καὶ τὸ κατὰ μέρος, οὗτος δὲ τὴν καθόλου
οὐκ οἶδεν· ὥστε κἂν οὕτως αἱρετωτέρα εἴη. Ἔτι δὲ ὧδε.
τὸ γὰρ καθόλου μᾶλλον δεικνύναι ἐστὶ τὸ διὰ μέσου δεικνύναι
15 ἐγγυτέρω ὄντος τῆς ἀρχῆς. ἐγγυτάτω δὲ τὸ ἄμεσον·
τοῦτο δ' ἀρχή. εἰ οὖν ἡ ἐξ ἀρχῆς τῆς μὴ ἐξ ἀρχῆς,
ἡ μᾶλλον ἐξ ἀρχῆς τῆς ἧττον ἀκριβεστέρα ἀπόδειξις. ἔστι
δὲ τοιαύτη ἡ καθόλου μᾶλλον· κρείττων <ἄρ'> ἂν εἴη ἡ καθόλου.
οἷον εἰ ἔδει ἀποδεῖξαι τὸ Α κατὰ τοῦ Δ· μέσα τὰ
20 ἐφ' ὧν Β Γ· ἀνωτέρω δὴ τὸ Β, ὥστε ἡ διὰ τούτου καθόλου
μᾶλλον.
Ἀλλὰ τῶν μὲν εἰρημένων ἔνια λογικά ἐστι· μάλιστα
δὲ δῆλον ὅτι ἡ καθόλου κυριωτέρα, ὅτι τῶν προτάσεων τὴν
μὲν προτέραν ἔχοντες ἴσμεν πως καὶ τὴν ὑστέραν καὶ ἔχομεν
25 δυνάμει, οἷον εἴ τις οἶδεν ὅτι πᾶν τρίγωνον δυσὶν ὀρθαῖς,
οἶδέ πως καὶ τὸ ἰσοσκελὲς ὅτι δύο ὀρθαῖς, δυνάμει, καὶ
εἰ μὴ οἶδε τὸ ἰσοσκελὲς ὅτι τρίγωνον· ὁ δὲ ταύτην ἔχων
τὴν πρότασιν τὸ καθόλου οὐδαμῶς οἶδεν, οὔτε δυνάμει οὔτ'
ἐνεργείᾳ. καὶ ἡ μὲν καθόλου νοητή, ἡ δὲ κατὰ μέρος εἰς
30 αἴσθησιν τελευτᾷ.
1If rectilinear figure possesses the property for no further reason, at this point we have full knowledge-but at this point our knowledge has become commensurately universal, and so we conclude that commensurately universal demonstration is superior.
(6) The more demonstration becomes particular the more it sinks into an indeterminate manifold, 5while universal demonstration tends to the simple and determinate. But objects so far as they are an indeterminate manifold are unintelligible, so far as they are determinate, intelligible: they are therefore intelligible rather in so far as they are universal than in so far as they are particular. From this it follows that universals are more demonstrable: but since relative and correlative increase concomitantly, of the more demonstrable there will be fuller demonstration. Hence the commensurate and universal form, 10being more truly demonstration, is the superior.
(7) Demonstration which teaches two things is preferable to demonstration which teaches only one. He who possesses commensurately universal demonstration knows the particular as well, but he who possesses particular demonstration does not know the universal. So that this is an additional reason for preferring commensurately universal demonstration. And there is yet this further argument:
(8) Proof becomes more and more proof of the commensurate universal 15as its middle term approaches nearer to the basic truth, and nothing is so near as the immediate premiss which is itself the basic truth. If, then, proof from the basic truth is more accurate than proof not so derived, demonstration which depends more closely on it is more accurate than demonstration which is less closely dependent. But commensurately universal demonstration is characterized by this closer dependence, and is therefore superior. Thus, if A had to be proved to inhere in D, and the middles were 20B and C, B being the higher term would render the demonstration which it mediated the more universal.
Some of these arguments, however, are dialectical. The clearest indication of the precedence of commensurately universal demonstration is as follows: if of two propositions, a prior and a posterior, we have a grasp of the prior, we have a kind of knowledge-a potential grasp-of the posterior as well. 25For example, if one knows that the angles of all triangles are equal to two right angles, one knows in a sense-potentially-that the isosceles' angles also are equal to two right angles, even if one does not know that the isosceles is a triangle; but to grasp this posterior proposition is by no means to know the commensurate universal either potentially or actually. Moreover, commensurately universal demonstration is through and through intelligible; 30particular demonstration issues in sense-perception.
(6) The more demonstration becomes particular the more it sinks into an indeterminate manifold, 5while universal demonstration tends to the simple and determinate. But objects so far as they are an indeterminate manifold are unintelligible, so far as they are determinate, intelligible: they are therefore intelligible rather in so far as they are universal than in so far as they are particular. From this it follows that universals are more demonstrable: but since relative and correlative increase concomitantly, of the more demonstrable there will be fuller demonstration. Hence the commensurate and universal form, 10being more truly demonstration, is the superior.
(7) Demonstration which teaches two things is preferable to demonstration which teaches only one. He who possesses commensurately universal demonstration knows the particular as well, but he who possesses particular demonstration does not know the universal. So that this is an additional reason for preferring commensurately universal demonstration. And there is yet this further argument:
(8) Proof becomes more and more proof of the commensurate universal 15as its middle term approaches nearer to the basic truth, and nothing is so near as the immediate premiss which is itself the basic truth. If, then, proof from the basic truth is more accurate than proof not so derived, demonstration which depends more closely on it is more accurate than demonstration which is less closely dependent. But commensurately universal demonstration is characterized by this closer dependence, and is therefore superior. Thus, if A had to be proved to inhere in D, and the middles were 20B and C, B being the higher term would render the demonstration which it mediated the more universal.
Some of these arguments, however, are dialectical. The clearest indication of the precedence of commensurately universal demonstration is as follows: if of two propositions, a prior and a posterior, we have a grasp of the prior, we have a kind of knowledge-a potential grasp-of the posterior as well. 25For example, if one knows that the angles of all triangles are equal to two right angles, one knows in a sense-potentially-that the isosceles' angles also are equal to two right angles, even if one does not know that the isosceles is a triangle; but to grasp this posterior proposition is by no means to know the commensurate universal either potentially or actually. Moreover, commensurately universal demonstration is through and through intelligible; 30particular demonstration issues in sense-perception.
Book 1,Chapter 25 (86a31–86b39)
Ὅτι μὲν οὖν ἡ καθόλου βελτίων τῆς κατὰ μέρος, τοσαῦθ'
ἡμῖν εἰρήσθω· ὅτι δ' ἡ δεικτικὴ τῆς στερητικῆς, ἐντεῦθεν
δῆλον. ἔστω γὰρ αὕτη ἡ ἀπόδειξις βελτίων τῶν ἄλλων
τῶν αὐτῶν ὑπαρχόντων, ἡ ἐξ ἐλαττόνων αἰτημάτων ἢ ὑποθέσεων
35 ἢ προτάσεων. εἰ γὰρ γνώριμοι ὁμοίως, τὸ θᾶττον
γνῶναι διὰ τούτων ὑπάρξει· τοῦτο δ' αἱρετώτερον. λόγος δὲ
τῆς προτάσεως, ὅτι βελτίων ἡ ἐξ ἐλαττόνων, καθόλου ὅδε·
εἰ γὰρ ὁμοίως εἴη τὸ γνώριμα εἶναι τὰ μέσα, τὰ δὲ πρότερα
γνωριμώτερα, ἔστω ἡ μὲν διὰ μέσων ἀπόδειξις τῶν
31The preceding arguments constitute our defence of the superiority of commensurately universal to particular demonstration. That affirmative demonstration excels negative may be shown as follows.
(1) We may assume the superiority ceteris paribus of the demonstration which derives from fewer postulates or hypotheses-35in short from fewer premisses; for, given that all these are equally well known, where they are fewer knowledge will be more speedily acquired, and that is a desideratum. The argument implied in our contention that demonstration from fewer assumptions is superior may be set out in universal form as follows.
(1) We may assume the superiority ceteris paribus of the demonstration which derives from fewer postulates or hypotheses-35in short from fewer premisses; for, given that all these are equally well known, where they are fewer knowledge will be more speedily acquired, and that is a desideratum. The argument implied in our contention that demonstration from fewer assumptions is superior may be set out in universal form as follows.
86b
1 Β Γ Δ ὅτι τὸ Α τῷ Ε ὑπάρχει, ἡ δὲ διὰ τῶν Ζ Η ὅτι
τὸ Α τῷ Ε. ὁμοίως δὴ ἔχει τὸ ὅτι τὸ Α τῷ Δ ὑπάρχει
καὶ τὸ Α τῷ Ε. τὸ δ' ὅτι τὸ Α τῷ Δ πρότερον καὶ γνωριμώτερον
ἢ ὅτι τὸ Α τῷ Ε· διὰ γὰρ τούτου ἐκεῖνο ἀποδείκνυται,
5 πιστότερον δὲ τὸ δι' οὗ. καὶ ἡ διὰ τῶν ἐλαττόνων
ἄρα ἀπόδειξις βελτίων τῶν ἄλλων τῶν αὐτῶν ὑπαρχόντων.
ἀμφότεραι μὲν οὖν διά τε ὅρων τριῶν καὶ προτάσεων
δύο δείκνυνται, ἀλλ' ἡ μὲν εἶναί τι λαμβάνει, ἡ δὲ
καὶ εἶναι καὶ μὴ εἶναί τι· διὰ πλειόνων ἄρα, ὥστε χείρων.
10 Ἔτι ἐπειδὴ δέδεικται ὅτι ἀδύνατον ἀμφοτέρων οὐσῶν
στερητικῶν τῶν προτάσεων γενέσθαι συλλογισμόν, ἀλλὰ τὴν
μὲν δεῖ τοιαύτην εἶναι, τὴν δ' ὅτι ὑπάρχει, ἔτι πρὸς τούτῳ
δεῖ τόδε λαβεῖν. τὰς μὲν γὰρ κατηγορικὰς αὐξανομένης τῆς
ἀποδείξεως ἀναγκαῖον γίνεσθαι πλείους, τὰς δὲ στερητικὰς
15 ἀδύνατον πλείους εἶναι μιᾶς ἐν ἅπαντι συλλογισμῷ. ἔστω
γὰρ μηδενὶ ὑπάρχον τὸ Α ἐφ' ὅσων τὸ Β, τῷ δὲ Γ ὑπάρχον
παντὶ τὸ Β. ἂν δὴ δέῃ πάλιν αὔξειν ἀμφοτέρας τὰς
προτάσεις, μέσον ἐμβλητέον. τοῦ μὲν Α Β ἔστω τὸ Δ, τοῦ δὲ
Β Γ τὸ Ε. τὸ μὲν δὴ Ε φανερὸν ὅτι κατηγορικόν, τὸ δὲ Δ
20 τοῦ μὲν Β κατηγορικόν, πρὸς δὲ τὸ Α στερητικὸν κεῖται.
τὸ μὲν γὰρ Δ παντὸς τοῦ Β, τὸ δὲ Α οὐδενὶ δεῖ τῶν Δ
ὑπάρχειν. γίνεται οὖν μία στερητικὴ πρότασις ἡ τὸ Α Δ. ὁ
δ' αὐτὸς τρόπος καὶ ἐπὶ τῶν ἑτέρων συλλογισμῶν. ἀεὶ γὰρ
τὸ μέσον τῶν κατηγορικῶν ὅρων κατηγορικὸν ἐπ' ἀμφότερα·
25 τοῦ δὲ στερητικοῦ ἐπὶ θάτερα στερητικὸν ἀναγκαῖον εἶναι, ὥστε
αὕτη μία τοιαύτη γίνεται πρότασις, αἱ δ' ἄλλαι κατηγορικαί.
εἰ δὴ γνωριμώτερον δι' οὗ δείκνυται καὶ πιστότερον,
δείκνυται δ' ἡ μὲν στερητικὴ διὰ τῆς κατηγορικῆς, αὕτη δὲ
δι' ἐκείνης οὐ δείκνυται, προτέρα καὶ γνωριμωτέρα οὖσα
30 καὶ πιστοτέρα βελτίων ἂν εἴη. ἔτι εἰ ἀρχὴ συλλογισμοῦ ἡ
καθόλου πρότασις ἄμεσος, ἔστι δ' ἐν μὲν τῇ δεικτικῇ καταφατικὴ
ἐν δὲ τῇ στερητικῇ ἀποφατικὴ ἡ καθόλου πρότασις,
ἡ δὲ καταφατικὴ τῆς ἀποφατικῆς προτέρα καὶ
γνωριμωτέρα (διὰ γὰρ τὴν κατάφασιν ἡ ἀπόφασις γνώριμος,
35 καὶ προτέρα ἡ κατάφασις, ὥσπερ καὶ τὸ εἶναι
τοῦ μὴ εἶναι)· ὥστε βελτίων ἡ ἀρχὴ τῆς δεικτικῆς ἢ τῆς
στερητικῆς· ἡ δὲ βελτίοσιν ἀρχαῖς χρωμένη βελτίων. ἔτι
ἀρχοειδεστέρα· ἄνευ γὰρ τῆς δεικνυούσης οὐκ ἔστιν ἡ στερητική.
1Assuming that in both cases alike the middle terms are known, and that middles which are prior are better known than such as are posterior, we may suppose two demonstrations of the inherence of A in E, the one proving it through the middles B, C and D, the other through F and G. Then A-D is known to the same degree as A-E (in the second proof), but A-D is better known than and prior to A-E (in the first proof); since A-E is proved through A-D, 5and the ground is more certain than the conclusion.
Hence demonstration by fewer premisses is ceteris paribus superior. Now both affirmative and negative demonstration operate through three terms and two premisses, but whereas the former assumes only that something is, the latter assumes both that something is and that something else is not, and thus operating through more kinds of premiss is inferior.
10(2) It has been proved that no conclusion follows if both premisses are negative, but that one must be negative, the other affirmative. So we are compelled to lay down the following additional rule: as the demonstration expands, the affirmative premisses must increase in number, 15but there cannot be more than one negative premiss in each complete proof. Thus, suppose no B is A, and all C is B. Then if both the premisses are to be again expanded, a middle must be interposed. Let us interpose D between A and B, and E between B and C. Then clearly E is affirmatively related to B and C, 20while D is affirmatively related to B but negatively to A; for all B is D, but there must be no D which is A. Thus there proves to be a single negative premiss, A-D. In the further prosyllogisms too it is the same, because in the terms of an affirmative syllogism the middle is always related affirmatively to both extremes; 25in a negative syllogism it must be negatively related only to one of them, and so this negation comes to be a single negative premiss, the other premisses being affirmative. If, then, that through which a truth is proved is a better known and more certain truth, and if the negative proposition is proved through the affirmative and not vice versa, affirmative demonstration, being prior and better known 30and more certain, will be superior.
(3) The basic truth of demonstrative syllogism is the universal immediate premiss, and the universal premiss asserts in affirmative demonstration and in negative denies: and the affirmative proposition is prior to and better known than the negative (since affirmation explains denial 35and is prior to denial, just as being is prior to not-being). It follows that the basic premiss of affirmative demonstration is superior to that of negative demonstration, and the demonstration which uses superior basic premisses is superior.
(4) Affirmative demonstration is more of the nature of a basic form of proof, because it is a sine qua non of negative demonstration.
Hence demonstration by fewer premisses is ceteris paribus superior. Now both affirmative and negative demonstration operate through three terms and two premisses, but whereas the former assumes only that something is, the latter assumes both that something is and that something else is not, and thus operating through more kinds of premiss is inferior.
10(2) It has been proved that no conclusion follows if both premisses are negative, but that one must be negative, the other affirmative. So we are compelled to lay down the following additional rule: as the demonstration expands, the affirmative premisses must increase in number, 15but there cannot be more than one negative premiss in each complete proof. Thus, suppose no B is A, and all C is B. Then if both the premisses are to be again expanded, a middle must be interposed. Let us interpose D between A and B, and E between B and C. Then clearly E is affirmatively related to B and C, 20while D is affirmatively related to B but negatively to A; for all B is D, but there must be no D which is A. Thus there proves to be a single negative premiss, A-D. In the further prosyllogisms too it is the same, because in the terms of an affirmative syllogism the middle is always related affirmatively to both extremes; 25in a negative syllogism it must be negatively related only to one of them, and so this negation comes to be a single negative premiss, the other premisses being affirmative. If, then, that through which a truth is proved is a better known and more certain truth, and if the negative proposition is proved through the affirmative and not vice versa, affirmative demonstration, being prior and better known 30and more certain, will be superior.
(3) The basic truth of demonstrative syllogism is the universal immediate premiss, and the universal premiss asserts in affirmative demonstration and in negative denies: and the affirmative proposition is prior to and better known than the negative (since affirmation explains denial 35and is prior to denial, just as being is prior to not-being). It follows that the basic premiss of affirmative demonstration is superior to that of negative demonstration, and the demonstration which uses superior basic premisses is superior.
(4) Affirmative demonstration is more of the nature of a basic form of proof, because it is a sine qua non of negative demonstration.
Book 1,Chapter 26 (87a1–30)
87a
1 Ἐπεὶ δ' ἡ κατηγορικὴ τῆς στερητικῆς βελτίων, δῆλον
ὅτι καὶ τῆς εἰς τὸ ἀδύνατον ἀγούσης. δεῖ δ' εἰδέναι τίς ἡ
διαφορὰ αὐτῶν. ἔστω δὴ τὸ Α μηδενὶ ὑπάρχον τῷ Β, τῷ
δὲ Γ τὸ Β παντί· ἀνάγκη δὴ τῷ Γ μηδενὶ ὑπάρχειν τὸ Α.
5 οὕτω μὲν οὖν ληφθέντων δεικτικὴ ἡ στερητικὴ ἂν εἴη ἀπόδειξις
ὅτι τὸ Α τῷ Γ οὐχ ὑπάρχει. ἡ δ' εἰς τὸ ἀδύνατον ὧδ'
ἔχει. εἰ δέοι δεῖξαι ὅτι τὸ Α τῷ Β οὐχ ὑπάρχει, ληπτέον
ὑπάρχειν, καὶ τὸ Β τῷ Γ, ὥστε συμβαίνει τὸ Α τῷ Γ
ὑπάρχειν. τοῦτο δ' ἔστω γνώριμον καὶ ὁμολογούμενον ὅτι
10 ἀδύνατον. οὐκ ἄρα οἷόν τε τὸ Α τῷ Β ὑπάρχειν. εἰ οὖν τὸ
Β τῷ Γ ὁμολογεῖται ὑπάρχειν, τὸ Α τῷ Β ἀδύνατον ὑπάρχειν.
οἱ μὲν οὖν ὅροι ὁμοίως τάττονται, διαφέρει δὲ τὸ
ὁποτέρα ἂν ᾖ γνωριμωτέρα ἡ πρότασις ἡ στερητική, πότερον
ὅτι τὸ Α τῷ Β οὐχ ὑπάρχει ἢ ὅτι τὸ Α τῷ Γ. ὅταν μὲν
15 οὖν ᾖ τὸ συμπέρασμα γνωριμώτερον ὅτι οὐκ ἔστιν, ἡ εἰς τὸ
ἀδύνατον γίνεται ἀπόδειξις, ὅταν δ' ἡ ἐν τῷ συλλογισμῷ,
ἡ ἀποδεικτική. φύσει δὲ προτέρα ἡ ὅτι τὸ Α τῷ Β ἢ ὅτι
τὸ Α τῷ Γ. πρότερα γάρ ἐστι τοῦ συμπεράσματος ἐξ ὧν
τὸ συμπέρασμα· ἔστι δὲ τὸ μὲν Α τῷ Γ μὴ ὑπάρχειν συμπέρασμα,
20 τὸ δὲ Α τῷ Β ἐξ οὗ τὸ συμπέρασμα. οὐ γὰρ
εἰ συμβαίνει ἀναιρεῖσθαί τι, τοῦτο συμπέρασμά ἐστιν, ἐκεῖνα
δὲ ἐξ ὧν, ἀλλὰ τὸ μὲν ἐξ οὗ συλλογισμός ἐστιν ὃ ἂν
οὕτως ἔχῃ ὥστε ἢ ὅλον πρὸς μέρος ἢ μέρος πρὸς ὅλον ἔχειν,
αἱ δὲ τὸ Α Γ καὶ Β Γ προτάσεις οὐκ ἔχουσιν οὕτω πρὸς
25 ἀλλήλας. εἰ οὖν ἡ ἐκ γνωριμωτέρων καὶ προτέρων κρείττων,
εἰσὶ δ' ἀμφότεραι ἐκ τοῦ μὴ εἶναί τι πισταί, ἀλλ' ἡ μὲν
ἐκ προτέρου ἡ δ' ἐξ ὑστέρου, βελτίων ἁπλῶς ἂν εἴη τῆς
εἰς τὸ ἀδύνατον ἡ στερητικὴ ἀπόδειξις, ὥστε καὶ ἡ ταύτης
βελτίων ἡ κατηγορικὴ δῆλον ὅτι καὶ τῆς εἰς τὸ ἀδύνατόν
30 ἐστι βελτίων.
1Since affirmative demonstration is superior to negative, it is clearly superior also to reductio ad impossibile. We must first make certain what is the difference between negative demonstration and reductio ad impossibile. Let us suppose that no B is A, and that all C is B: the conclusion necessarily follows that no C is A. 5If these premisses are assumed, therefore, the negative demonstration that no C is A is direct. Reductio ad impossibile, on the other hand, proceeds as follows. Supposing we are to prove that does not inhere in B, we have to assume that it does inhere, and further that B inheres in C, with the resulting inference that A inheres in C. This we have to suppose a known and admitted 10impossibility; and we then infer that A cannot inhere in B. Thus if the inherence of B in C is not questioned, A's inherence in B is impossible.
The order of the terms is the same in both proofs: they differ according to which of the negative propositions is the better known, the one denying A of B or the one denying A of C. When 15the falsity of the conclusion is the better known, we use reductio ad impossible; when the major premiss of the syllogism is the more obvious, we use direct demonstration. All the same the proposition denying A of B is, in the order of being, prior to that denying A of C; for premisses are prior to the conclusion which follows from them, and 'no C is A' is the conclusion, 20'no B is A' one of its premisses. For the destructive result of reductio ad impossibile is not a proper conclusion, nor are its antecedents proper premisses. On the contrary: the constituents of syllogism are premisses related to one another as whole to part or part to whole, whereas the premisses A-C and A-B are not thus related to 25one another. Now the superior demonstration is that which proceeds from better known and prior premisses, and while both these forms depend for credence on the not-being of something, yet the source of the one is prior to that of the other. Therefore negative demonstration will have an unqualified superiority to reductio ad impossibile, and affirmative demonstration, being superior to negative, 30will consequently be superior also to reductio ad impossibile.
The order of the terms is the same in both proofs: they differ according to which of the negative propositions is the better known, the one denying A of B or the one denying A of C. When 15the falsity of the conclusion is the better known, we use reductio ad impossible; when the major premiss of the syllogism is the more obvious, we use direct demonstration. All the same the proposition denying A of B is, in the order of being, prior to that denying A of C; for premisses are prior to the conclusion which follows from them, and 'no C is A' is the conclusion, 20'no B is A' one of its premisses. For the destructive result of reductio ad impossibile is not a proper conclusion, nor are its antecedents proper premisses. On the contrary: the constituents of syllogism are premisses related to one another as whole to part or part to whole, whereas the premisses A-C and A-B are not thus related to 25one another. Now the superior demonstration is that which proceeds from better known and prior premisses, and while both these forms depend for credence on the not-being of something, yet the source of the one is prior to that of the other. Therefore negative demonstration will have an unqualified superiority to reductio ad impossibile, and affirmative demonstration, being superior to negative, 30will consequently be superior also to reductio ad impossibile.
Book 1,Chapter 27 (87a31–37)
Ἀκριβεστέρα δ' ἐπιστήμη ἐπιστήμης καὶ προτέρα ἥ τε
τοῦ ὅτι καὶ διότι ἡ αὐτή, ἀλλὰ μὴ χωρὶς τοῦ ὅτι τῆς τοῦ
διότι, καὶ ἡ μὴ καθ' ὑποκειμένου τῆς καθ' ὑποκειμένου,
οἷον ἀριθμητικὴ ἁρμονικῆς, καὶ ἡ ἐξ ἐλαττόνων τῆς ἐκ προςθέσεως,
35 οἷον γεωμετρίας ἀριθμητική. λέγω δ' ἐκ προσθέσεως,
οἷον μονὰς οὐσία ἄθετος, στιγμὴ δὲ οὐσία θετός· ταύτην
ἐκ προσθέσεως.
31The science which is knowledge at once of the fact and of the reasoned fact, not of the fact by itself without the reasoned fact, is the more exact and the prior science.
A science such as arithmetic, which is not a science of properties qua inhering in a substratum, is more exact than and prior to a science like harmonics, which is a science of pr,operties inhering in a substratum; and similarly a science like arithmetic, which is constituted of fewer basic elements, 35is more exact than and prior to geometry, which requires additional elements. What I mean by 'additional elements' is this: a unit is substance without position, while a point is substance with position; the latter contains an additional element.
A science such as arithmetic, which is not a science of properties qua inhering in a substratum, is more exact than and prior to a science like harmonics, which is a science of pr,operties inhering in a substratum; and similarly a science like arithmetic, which is constituted of fewer basic elements, 35is more exact than and prior to geometry, which requires additional elements. What I mean by 'additional elements' is this: a unit is substance without position, while a point is substance with position; the latter contains an additional element.
Book 1,Chapter 28 (87a38–87b4)
Μία δ' ἐπιστήμη ἐστὶν ἡ ἑνὸς γένους, ὅσα ἐκ τῶν πρώτων
σύγκειται καὶ μέρη ἐστὶν ἢ πάθη τούτων καθ' αὑτά. ἑτέρα
40 δ' ἐπιστήμη ἐστὶν ἑτέρας, ὅσων αἱ ἀρχαὶ μήτ' ἐκ τῶν αὐτῶν
38A single science is one whose domain is a single genus, viz. all the subjects constituted out of the primary entities of the genus-i.e. 40the parts of this total subject-and their essential properties.
87b
1 μήθ' ἅτεραι ἐκ τῶν ἑτέρων. τούτου δὲ σημεῖον, ὅταν εἰς
τὰ ἀναπόδεικτα ἔλθῃ· δεῖ γὰρ αὐτὰ ἐν τῷ αὐτῷ γένει εἶναι
τοῖς ἀποδεδειγμένοις. σημεῖον δὲ καὶ τούτου, ὅταν τὰ
δεικνύμενα δι' αὐτῶν ἐν ταὐτῷ γένει ὦσι καὶ συγγενῆ.
1One science differs from another when their basic truths have neither a common source nor are derived those of the one science from those the other. This is verified when we reach the indemonstrable premisses of a science, for they must be within one genus with its conclusions: and this again is verified if the conclusions proved by means of them fall within one genus-i.e. are homogeneous.
Book 1,Chapter 29 (87b5–18)
5 Πλείους δ' ἀποδείξεις εἶναι τοῦ αὐτοῦ ἐγχωρεῖ οὐ μόνον
ἐκ τῆς αὐτῆς συστοιχίας λαμβάνοντι μὴ τὸ συνεχὲς μέσον,
οἷον τῶν Α Β τὸ Γ καὶ Δ καὶ Ζ, ἀλλὰ καὶ ἐξ ἑτέρας. οἷον
ἔστω τὸ Α μεταβάλλειν, τὸ δ' ἐφ' ᾧ Δ κινεῖσθαι, τὸ δὲ Β
ἥδεσθαι, καὶ πάλιν τὸ Η ἠρεμίζεσθαι. ἀληθὲς οὖν καὶ τὸ Δ
10 τοῦ Β καὶ τὸ Α τοῦ Δ κατηγορεῖν· ὁ γὰρ ἡδόμενος κινεῖται
καὶ τὸ κινούμενον μεταβάλλει. πάλιν τὸ Α τοῦ Η καὶ τὸ Η
τοῦ Β ἀληθὲς κατηγορεῖν· πᾶς γὰρ ὁ ἡδόμενος ἠρεμίζεται
καὶ ὁ ἠρεμιζόμενος μεταβάλλει. ὥστε δι' ἑτέρων μέσων καὶ
οὐκ ἐκ τῆς αὐτῆς συστοιχίας ὁ συλλογισμός. οὐ μὴν ὥστε μηδέτερον
15 κατὰ μηδετέρου λέγεσθαι τῶν μέσων· ἀνάγκη γὰρ
τῷ αὐτῷ τινι ἄμφω ὑπάρχειν. ἐπισκέψασθαι δὲ καὶ διὰ
τῶν ἄλλων σχημάτων ὁσαχῶς ἐνδέχεται τοῦ αὐτοῦ γενέσθαι
συλλογισμόν.
5One can have several demonstrations of the same connexion not only by taking from the same series of predication middles which are other than the immediately cohering term e.g. by taking C, D, and F severally to prove A-B--but also by taking a middle from another series. Thus let A be change, D alteration of a property, B feeling pleasure, and G relaxation. We can then without falsehood predicate D 10of B and A of D, for he who is pleased suffers alteration of a property, and that which alters a property changes. Again, we can predicate A of G without falsehood, and G of B; for to feel pleasure is to relax, and to relax is to change. So the conclusion can be drawn through middles which are different, i.e. not in the same series-yet not so that neither 15of these middles is predicable of the other, for they must both be attributable to some one subject.
A further point worth investigating is how many ways of proving the same conclusion can be obtained by varying the figure,
A further point worth investigating is how many ways of proving the same conclusion can be obtained by varying the figure,
Book 1,Chapter 30 (87b19–27)
Τοῦ δ' ἀπὸ τύχης οὐκ ἔστιν ἐπιστήμη δι' ἀποδείξεως.
20 οὔτε γὰρ ὡς ἀναγκαῖον οὔθ' ὡς ἐπὶ τὸ πολὺ τὸ ἀπὸ τύχης
ἐστίν, ἀλλὰ τὸ παρὰ ταῦτα γινόμενον· ἡ δ' ἀπόδειξις θατέρου
τούτων. πᾶς γὰρ συλλογισμὸς ἢ δι' ἀναγκαίων ἢ
διὰ τῶν ὡς ἐπὶ τὸ πολὺ προτάσεων· καὶ εἰ μὲν αἱ προτάσεις
ἀναγκαῖαι, καὶ τὸ συμπέρασμα ἀναγκαῖον, εἰ δ' ὡς
25 ἐπὶ τὸ πολύ, καὶ τὸ συμπέρασμα τοιοῦτον. ὥστ' εἰ τὸ ἀπὸ
τύχης μήθ' ὡς ἐπὶ τὸ πολὺ μήτ' ἀναγκαῖον, οὐκ ἂν εἴη
αὐτοῦ ἀπόδειξις.
19There is no knowledge by demonstration of chance conjunctions; 20for chance conjunctions exist neither by necessity nor as general connexions but comprise what comes to be as something distinct from these. Now demonstration is concerned only with one or other of these two; for all reasoning proceeds from necessary or general premisses, the conclusion being necessary if the premisses are necessary and 25general if the premisses are general. Consequently, if chance conjunctions are neither general nor necessary, they are not demonstrable.
Book 1,Chapter 31 (87b28–88a17)
Οὐδὲ δι' αἰσθήσεως ἔστιν ἐπίστασθαι. εἰ γὰρ καὶ ἔστιν
ἡ αἴσθησις τοῦ τοιοῦδε καὶ μὴ τοῦδέ τινος, ἀλλ' αἰσθάνεσθαί
30 γε ἀναγκαῖον τόδε τι καὶ ποὺ καὶ νῦν. τὸ δὲ καθόλου καὶ
ἐπὶ πᾶσιν ἀδύνατον αἰσθάνεσθαι· οὐ γὰρ τόδε οὐδὲ νῦν· οὐ
γὰρ ἂν ἦν καθόλου· τὸ γὰρ ἀεὶ καὶ πανταχοῦ καθόλου
φαμὲν εἶναι. ἐπεὶ οὖν αἱ μὲν ἀποδείξεις καθόλου, ταῦτα δ'
οὐκ ἔστιν αἰσθάνεσθαι, φανερὸν ὅτι οὐδ' ἐπίστασθαι δι' αἰσθήσεως
35 ἔστιν, ἀλλὰ δῆλον ὅτι καὶ εἰ ἦν αἰσθάνεσθαι τὸ τρίγωνον
ὅτι δυσὶν ὀρθαῖς ἴσας ἔχει τὰς γωνίας, ἐζητοῦμεν ἂν
ἀπόδειξιν καὶ οὐχ ὥσπερ φασί τινες ἠπιστάμεθα· αἰσθάνεσθαι
μὲν γὰρ ἀνάγκη καθ' ἕκαστον, ἡ δ' ἐπιστήμη τὸ τὸ
καθόλου γνωρίζειν ἐστίν. διὸ καὶ εἰ ἐπὶ τῆς σελήνης ὄντες
40 ἑωρῶμεν ἀντιφράττουσαν τὴν γῆν, οὐκ ἂν ᾔδειμεν τὴν αἰτίαν
28Scientific knowledge is not possible through the act of perception. Even if perception as a faculty is of 'the such' and not merely of a 'this somewhat', 30yet one must at any rate actually perceive a 'this somewhat', and at a definite present place and time: but that which is commensurately universal and true in all cases one cannot perceive, since it is not 'this' and it is not 'now'; if it were, it would not be commensurately universal-the term we apply to what is always and everywhere. 40Seeing, therefore, that demonstrations are commensurately universal and universals imperceptible, we clearly cannot obtain scientific knowledge by the act of perception: 35nay, it is obvious that even if it were possible to perceive that a triangle has its angles equal to two right angles, we should still be looking for a demonstration-we should not (as some say) possess knowledge of it; for perception must be of a particular, whereas scientific knowledge involves the recognition of the commensurate universal.
88a
1 τῆς ἐκλείψεως. ᾐσθανόμεθα γὰρ ἂν ὅτι νῦν ἐκλείπει, καὶ
οὐ διότι ὅλως· οὐ γὰρ ἦν τοῦ καθόλου αἴσθησις. οὐ μὴν ἀλλ'
ἐκ τοῦ θεωρεῖν τοῦτο πολλάκις συμβαῖνον τὸ καθόλου ἂν θηρεύσαντες
ἀπόδειξιν εἴχομεν· ἐκ γὰρ τῶν καθ' ἕκαστα πλειόνων
5 τὸ καθόλου δῆλον. τὸ δὲ καθόλου τίμιον, ὅτι δηλοῖ τὸ
αἴτιον· ὥστε περὶ τῶν τοιούτων ἡ καθόλου τιμιωτέρα τῶν αἰσθήσεων
καὶ τῆς νοήσεως, ὅσων ἕτερον τὸ αἴτιον· περὶ δὲ
τῶν πρώτων ἄλλος λόγος.
Φανερὸν οὖν ὅτι ἀδύνατον τῷ αἰσθάνεσθαι ἐπίστασθαί τι
10 τῶν ἀποδεικτῶν, εἰ μή τις τὸ αἰσθάνεσθαι τοῦτο λέγει, τὸ
ἐπιστήμην ἔχειν δι' ἀποδείξεως. ἔστι μέντοι ἔνια ἀναγόμενα
εἰς αἰσθήσεως ἔκλειψιν ἐν τοῖς προβλήμασιν. ἔνια γὰρ εἰ
ἑωρῶμεν οὐκ ἂν ἐζητοῦμεν, οὐχ ὡς εἰδότες τῷ ὁρᾶν, ἀλλ' ὡς
ἔχοντες τὸ καθόλου ἐκ τοῦ ὁρᾶν. οἷον εἰ τὴν ὕαλον τετρυπημένην
15 ἑωρῶμεν καὶ τὸ φῶς διιόν, δῆλον ἂν ἦν καὶ διὰ τί
καίει, τῷ ὁρᾶν μὲν χωρὶς ἐφ' ἑκάστης, νοῆσαι δ' ἅμα ὅτι
ἐπὶ πασῶν οὕτως.
1So if we were on the moon, and saw the earth shutting out the sun's light, we should not know the cause of the eclipse: we should perceive the present fact of the eclipse, but not the reasoned fact at all, since the act of perception is not of the commensurate universal. I do not, of course, deny that by watching the frequent recurrence of this event we might, after tracking the commensurate universal, possess a demonstration, for the commensurate universal is elicited from the several groups of singulars.
5The commensurate universal is precious because it makes clear the cause; so that in the case of facts like these which have a cause other than themselves universal knowledge is more precious than sense-perceptions and than intuition. (As regards primary truths there is of course a different account to be given.) Hence it is clear that knowledge 10of things demonstrable cannot be acquired by perception, unless the term perception is applied to the possession of scientific knowledge through demonstration. Nevertheless certain points do arise with regard to connexions to be proved which are referred for their explanation to a failure in sense-perception: there are cases when an act of vision would terminate our inquiry, not because in seeing we should be knowing, but because we should have elicited the universal from seeing; if, for example, we saw the pores in the glass 15and the light passing through, the reason of the kindling would be clear to us because we should at the same time see it in each instance and intuit that it must be so in all instances.
5The commensurate universal is precious because it makes clear the cause; so that in the case of facts like these which have a cause other than themselves universal knowledge is more precious than sense-perceptions and than intuition. (As regards primary truths there is of course a different account to be given.) Hence it is clear that knowledge 10of things demonstrable cannot be acquired by perception, unless the term perception is applied to the possession of scientific knowledge through demonstration. Nevertheless certain points do arise with regard to connexions to be proved which are referred for their explanation to a failure in sense-perception: there are cases when an act of vision would terminate our inquiry, not because in seeing we should be knowing, but because we should have elicited the universal from seeing; if, for example, we saw the pores in the glass 15and the light passing through, the reason of the kindling would be clear to us because we should at the same time see it in each instance and intuit that it must be so in all instances.
Book 1,Chapter 32 (88a18–88b29)
Τὰς δ' αὐτὰς ἀρχὰς ἁπάντων εἶναι τῶν συλλογισμῶν
ἀδύνατον, πρῶτον μὲν λογικῶς θεωροῦσιν. οἱ μὲν γὰρ ἀληθεῖς
20 εἰσι τῶν συλλογισμῶν, οἱ δὲ ψευδεῖς. καὶ γὰρ εἰ ἔστιν
ἀληθὲς ἐκ ψευδῶν συλλογίσασθαι, ἀλλ' ἅπαξ τοῦτο γίνεται,
οἷον εἰ τὸ Α κατὰ τοῦ Γ ἀληθές, τὸ δὲ μέσον τὸ Β ψεῦδος·
οὔτε γὰρ τὸ Α τῷ Β ὑπάρχει οὔτε τὸ Β τῷ Γ. ἀλλ'
ἐὰν τούτων μέσα λαμβάνηται τῶν προτάσεων, ψευδεῖς
25 ἔσονται διὰ τὸ πᾶν συμπέρασμα ψεῦδος ἐκ ψευδῶν εἶναι,
τὰ δ' ἀληθῆ ἐξ ἀληθῶν, ἕτερα δὲ τὰ ψευδῆ καὶ τἀληθῆ.
εἶτα οὐδὲ τὰ ψευδῆ ἐκ τῶν αὐτῶν ἑαυτοῖς· ἔστι γὰρ ψευδῆ
ἀλλήλοις καὶ ἐναντία καὶ ἀδύνατα ἅμα εἶναι, οἷον τὸ τὴν
δικαιοσύνην εἶναι ἀδικίαν ἢ δειλίαν, καὶ τὸν ἄνθρωπον ἵππον
30 ἢ βοῦν, ἢ τὸ ἴσον μεῖζον ἢ ἔλαττον. Ἐκ δὲ τῶν κειμένων
ὧδε· οὐδὲ γὰρ τῶν ἀληθῶν αἱ αὐταὶ ἀρχαὶ πάντων. ἕτεραι
γὰρ πολλῶν τῷ γένει αἱ ἀρχαί, καὶ οὐδ' ἐφαρμόττουσαι,
οἷον αἱ μονάδες ταῖς στιγμαῖς οὐκ ἐφαρμόττουσιν· αἱ μὲν
γὰρ οὐκ ἔχουσι θέσιν, αἱ δὲ ἔχουσιν. ἀνάγκη δέ γε ἢ εἰς
35 μέσα ἁρμόττειν ἢ ἄνωθεν ἢ κάτωθεν, ἢ τοὺς μὲν εἴσω ἔχειν
τοὺς δ' ἔξω τῶν ὅρων. ἀλλ' οὐδὲ τῶν κοινῶν ἀρχῶν οἷόν τ'
εἶναί τινας ἐξ ὧν ἅπαντα δειχθήσεται· λέγω δὲ κοινὰς
18All syllogisms cannot have the same basic truths. This may be shown first of all by the following dialectical considerations. (1) Some syllogisms are true and 20some false: for though a true inference is possible from false premisses, yet this occurs once only-I mean if A for instance, is truly predicable of C, but B, the middle, is false, both A-B and B-C being false; nevertheless, if middles are taken to prove these premisses, 25they will be false because every conclusion which is a falsehood has false premisses, while true conclusions have true premisses, and false and true differ in kind. Then again, (2) falsehoods are not all derived from a single identical set of principles: there are falsehoods which are the contraries of one another and cannot coexist, e.g. 'justice is injustice', and 'justice is cowardice'; 'man is horse', and '30man is ox'; 'the equal is greater', and 'the equal is less.' From established principles we may argue the case as follows, confining-ourselves therefore to true conclusions. Not even all these are inferred from the same basic truths; many of them in fact have basic truths which differ generically and are not transferable; units, for instance, which are without position, cannot take the place of points, which have position. The transferred terms could only fit in 35as middle terms or as major or minor terms, or else have some of the other terms between them, others outside them.
Nor can any of the common axioms-such, I mean, as the law of excluded middle-serve as premisses for the proof of all conclusions.
Nor can any of the common axioms-such, I mean, as the law of excluded middle-serve as premisses for the proof of all conclusions.
88b
1 οἷον τὸ πᾶν φάναι ἢ ἀποφάναι. τὰ γὰρ γένη τῶν ὄντων
ἕτερα, καὶ τὰ μὲν τοῖς ποσοῖς τὰ δὲ τοῖς ποιοῖς ὑπάρχει
μόνοις, μεθ' ὧν δείκνυται διὰ τῶν κοινῶν. ἔτι αἱ ἀρχαὶ οὐ
πολλῷ ἐλάττους τῶν συμπερασμάτων· ἀρχαὶ μὲν γὰρ αἱ
5 προτάσεις, αἱ δὲ προτάσεις ἢ προσλαμβανομένου ὅρου ἢ ἐμβαλλομένου
εἰσίν. ἔτι τὰ συμπεράσματα ἄπειρα, οἱ δ' ὅροι
πεπερασμένοι. ἔτι αἱ ἀρχαὶ αἱ μὲν ἐξ ἀνάγκης, αἱ δ' ἐνδεχόμεναι.
Οὕτω μὲν οὖν σκοπουμένοις ἀδύνατον τὰς αὐτὰς εἶναι
10 πεπερασμένας, ἀπείρων ὄντων τῶν συμπερασμάτων. εἰ δ'
ἄλλως πως λέγοι τις, οἷον ὅτι αἱδὶ μὲν γεωμετρίας αἱδὶ δὲ
λογισμῶν αἱδὶ δὲ ἰατρικῆς, τί ἂν εἴη τὸ λεγόμενον ἄλλο
πλὴν ὅτι εἰσὶν ἀρχαὶ τῶν ἐπιστημῶν; τὸ δὲ τὰς αὐτὰς φάναι
γελοῖον, ὅτι αὐταὶ αὑταῖς αἱ αὐταί· πάντα γὰρ οὕτω
15 γίγνεται ταὐτά. ἀλλὰ μὴν οὐδὲ τὸ ἐξ ἁπάντων δείκνυσθαι
ὁτιοῦν, τοῦτ' ἐστὶ τὸ ζητεῖν ἁπάντων εἶναι τὰς αὐτὰς ἀρχάς·
λίαν γὰρ εὔηθες. οὔτε γὰρ ἐν τοῖς φανεροῖς μαθήμασι τοῦτο
γίνεται, οὔτ' ἐν τῇ ἀναλύσει δυνατόν· αἱ γὰρ ἄμεσοι προτάσεις
ἀρχαί, ἕτερον δὲ συμπέρασμα προσληφθείσης γίνεται
20 προτάσεως ἀμέσου. εἰ δὲ λέγοι τις τὰς πρώτας ἀμέσους
προτάσεις, ταύτας εἶναι ἀρχάς, μία ἐν ἑκάστῳ γένει ἐστίν. εἰ
δὲ μήτ' ἐξ ἁπασῶν ὡς δέον δείκνυσθαι ὁτιοῦν μήθ' οὕτως ἑτέρας
ὥσθ' ἑκάστης ἐπιστήμης εἶναι ἑτέρας, λείπεται εἰ συγγενεῖς
αἱ ἀρχαὶ πάντων, ἀλλ' ἐκ τωνδὶ μὲν ταδί, ἐκ δὲ
25 τωνδὶ ταδί. φανερὸν δὲ καὶ τοῦθ' ὅτι οὐκ ἐνδέχεται· δέδεικται
γὰρ ὅτι ἄλλαι ἀρχαὶ τῷ γένει εἰσὶν αἱ τῶν διαφόρων
τῷ γένει. αἱ γὰρ ἀρχαὶ διτταί, ἐξ ὧν τε καὶ περὶ ὅ·
αἱ μὲν οὖν ἐξ ὧν κοιναί, αἱ δὲ περὶ ὃ ἴδιαι, οἷον ἀριθμός,
μέγεθος.
1For the kinds of being are different, and some attributes attach to quanta and some to qualia only; and proof is achieved by means of the common axioms taken in conjunction with these several kinds and their attributes.
Again, it is not true that the basic truths are much fewer than the conclusions, for the basic truths are the 5premisses, and the premisses are formed by the apposition of a fresh extreme term or the interposition of a fresh middle. Moreover, the number of conclusions is indefinite, though the number of middle terms is finite; and lastly some of the basic truths are necessary, others variable.
Looking at it in this way we see that, 10since the number of conclusions is indefinite, the basic truths cannot be identical or limited in number. If, on the other hand, identity is used in another sense, and it is said, e.g. 'these and no other are the fundamental truths of geometry, these the fundamentals of calculation, these again of medicine'; would the statement mean anything except that the sciences have basic truths? To call them identical because they are self-identical is absurd, since 15everything can be identified with everything in that sense of identity. Nor again can the contention that all conclusions have the same basic truths mean that from the mass of all possible premisses any conclusion may be drawn. That would be exceedingly naive, for it is not the case in the clearly evident mathematical sciences, nor is it possible in analysis, since it is the immediate premisses which are the basic truths, and a fresh conclusion is only formed by the addition of a new 20immediate premiss: but if it be admitted that it is these primary immediate premisses which are basic truths, each subject-genus will provide one basic truth. If, however, it is not argued that from the mass of all possible premisses any conclusion may be proved, nor yet admitted that basic truths differ so as to be generically different for each science, it remains to consider the possibility that, while the basic truths of all knowledge are within one genus, special premisses are required to prove 25special conclusions. But that this cannot be the case has been shown by our proof that the basic truths of things generically different themselves differ generically. For fundamental truths are of two kinds, those which are premisses of demonstration and the subject-genus; and though the former are common, the latter-number, for instance, and magnitude-are peculiar.
Again, it is not true that the basic truths are much fewer than the conclusions, for the basic truths are the 5premisses, and the premisses are formed by the apposition of a fresh extreme term or the interposition of a fresh middle. Moreover, the number of conclusions is indefinite, though the number of middle terms is finite; and lastly some of the basic truths are necessary, others variable.
Looking at it in this way we see that, 10since the number of conclusions is indefinite, the basic truths cannot be identical or limited in number. If, on the other hand, identity is used in another sense, and it is said, e.g. 'these and no other are the fundamental truths of geometry, these the fundamentals of calculation, these again of medicine'; would the statement mean anything except that the sciences have basic truths? To call them identical because they are self-identical is absurd, since 15everything can be identified with everything in that sense of identity. Nor again can the contention that all conclusions have the same basic truths mean that from the mass of all possible premisses any conclusion may be drawn. That would be exceedingly naive, for it is not the case in the clearly evident mathematical sciences, nor is it possible in analysis, since it is the immediate premisses which are the basic truths, and a fresh conclusion is only formed by the addition of a new 20immediate premiss: but if it be admitted that it is these primary immediate premisses which are basic truths, each subject-genus will provide one basic truth. If, however, it is not argued that from the mass of all possible premisses any conclusion may be proved, nor yet admitted that basic truths differ so as to be generically different for each science, it remains to consider the possibility that, while the basic truths of all knowledge are within one genus, special premisses are required to prove 25special conclusions. But that this cannot be the case has been shown by our proof that the basic truths of things generically different themselves differ generically. For fundamental truths are of two kinds, those which are premisses of demonstration and the subject-genus; and though the former are common, the latter-number, for instance, and magnitude-are peculiar.
Book 1,Chapter 33 (88b30–89b9)
30 Τὸ δ' ἐπιστητὸν καὶ ἐπιστήμη διαφέρει τοῦ δοξαστοῦ καὶ
δόξης, ὅτι ἡ μὲν ἐπιστήμη καθόλου καὶ δι' ἀναγκαίων, τὸ
δ' ἀναγκαῖον οὐκ ἐνδέχεται ἄλλως ἔχειν. ἔστι δέ τινα ἀληθῆ
μὲν καὶ ὄντα, ἐνδεχόμενα δὲ καὶ ἄλλως ἔχειν. δῆλον οὖν
ὅτι περὶ μὲν ταῦτα ἐπιστήμη οὐκ ἔστιν· εἴη γὰρ ἂν ἀδύνατα
35 ἄλλως ἔχειν τὰ δυνατὰ ἄλλως ἔχειν. ἀλλὰ μὴν οὐδὲ νοῦς
(λέγω γὰρ νοῦν ἀρχὴν ἐπιστήμης) οὐδ' ἐπιστήμη ἀναπόδεικτος·
τοῦτο δ' ἐστὶν ὑπόληψις τῆς ἀμέσου προτάσεως. ἀληθὴς δ'
30Scientific knowledge and its object differ from opinion and the object of opinion in that scientific knowledge is commensurately universal and proceeds by necessary connexions, and that which is necessary cannot be otherwise. So though there are things which are true and real and yet can be otherwise, scientific knowledge clearly does not concern them: if it did, things which can be otherwise 35would be incapable of being otherwise. Nor are they any concern of rational intuition-by rational intuition I mean an originative source of scientific knowledge-nor of indemonstrable knowledge, which is the grasping of the immediate premiss.
89a
1 ἐστὶ νοῦς καὶ ἐπιστήμη καὶ δόξα καὶ τὸ διὰ τούτων λεγόμενον·
ὥστε λείπεται δόξαν εἶναι περὶ τὸ ἀληθὲς μὲν ἢ ψεῦδος,
ἐνδεχόμενον δὲ καὶ ἄλλως ἔχειν. τοῦτο δ' ἐστὶν ὑπόληψις
τῆς ἀμέσου προτάσεως καὶ μὴ ἀναγκαίας. καὶ ὁμολογούμενον
5 δ' οὕτω τοῖς φαινομένοις· ἥ τε γὰρ δόξα ἀβέβαιον,
καὶ ἡ φύσις ἡ τοιαύτη. πρὸς δὲ τούτοις οὐδεὶς οἴεται
δοξάζειν, ὅταν οἴηται ἀδύνατον ἄλλως ἔχειν, ἀλλ' ἐπίστασθαι·
ἀλλ' ὅταν εἶναι μὲν οὕτως, οὐ μὴν ἀλλὰ καὶ ἄλλως
οὐδὲν κωλύειν, τότε δοξάζειν, ὡς τοῦ μὲν τοιούτου δόξαν οὖσαν,
10 τοῦ δ' ἀναγκαίου ἐπιστήμην.
Πῶς οὖν ἔστι τὸ αὐτὸ δοξάσαι καὶ ἐπίστασθαι, καὶ διὰ
τί οὐκ ἔσται ἡ δόξα ἐπιστήμη, εἴ τις θήσει ἅπαν ὃ οἶδεν ἐνδέχεσθαι
δοξάζειν; ἀκολουθήσει γὰρ ὁ μὲν εἰδὼς ὁ δὲ δοξάζων
διὰ τῶν μέσων, ἕως εἰς τὰ ἄμεσα ἔλθῃ, ὥστ' εἴπερ
15 ἐκεῖνος οἶδε, καὶ ὁ δοξάζων οἶδεν. ὥσπερ γὰρ καὶ τὸ ὅτι
δοξάζειν ἔστι, καὶ τὸ διότι· τοῦτο δὲ τὸ μέσον. ἢ εἰ μὲν
οὕτως ὑπολήψεται τὰ μὴ ἐνδεχόμενα ἄλλως ἔχειν ὥσπερ
[ἔχει] τοὺς ὁρισμοὺς δι' ὧν αἱ ἀποδείξεις, οὐ δοξάσει ἀλλ' ἐπιστήσεται·
εἰ δ' ἀληθῆ μὲν εἶναι, οὐ μέντοι ταῦτά γε αὐτοῖς
20 ὑπάρχειν κατ' οὐσίαν καὶ κατὰ τὸ εἶδος, δοξάσει καὶ οὐκ
ἐπιστήσεται ἀληθῶς, καὶ τὸ ὅτι καὶ τὸ διότι, ἐὰν μὲν διὰ
τῶν ἀμέσων δοξάσῃ· ἐὰν δὲ μὴ διὰ τῶν ἀμέσων, τὸ ὅτι
μόνον δοξάσει; τοῦ δ' αὐτοῦ δόξα καὶ ἐπιστήμη οὐ πάντως
ἐστίν, ἀλλ' ὥσπερ καὶ ψευδὴς καὶ ἀληθὴς τοῦ αὐτοῦ τρόπον
25 τινά, οὕτω καὶ ἐπιστήμη καὶ δόξα τοῦ αὐτοῦ. καὶ γὰρ
δόξαν ἀληθῆ καὶ ψευδῆ ὡς μέν τινες λέγουσι τοῦ αὐτοῦ
εἶναι, ἄτοπα συμβαίνει αἱρεῖσθαι ἄλλα τε καὶ μὴ δοξάζειν
ὃ δοξάζει ψευδῶς· ἐπεὶ δὲ τὸ αὐτὸ πλεοναχῶς λέγεται,
ἔστιν ὡς ἐνδέχεται, ἔστι δ' ὡς οὔ. τὸ μὲν γὰρ
30 σύμμετρον εἶναι τὴν διάμετρον ἀληθῶς δοξάζειν ἄτοπον·
ἀλλ' ὅτι ἡ διάμετρος, περὶ ἣν αἱ δόξαι, τὸ αὐτό, οὕτω τοῦ
αὐτοῦ, τὸ δὲ τί ἦν εἶναι ἑκατέρῳ κατὰ τὸν λόγον οὐ τὸ αὐτό.
ὁμοίως δὲ καὶ ἐπιστήμη καὶ δόξα τοῦ αὐτοῦ. ἡ μὲν γὰρ
οὕτως τοῦ ζῴου ὥστε μὴ ἐνδέχεσθαι μὴ εἶναι ζῷον, ἡ δ'
35 ὥστ' ἐνδέχεσθαι, οἷον εἰ ἡ μὲν ὅπερ ἀνθρώπου ἐστίν, ἡ δ'
ἀνθρώπου μέν, μὴ ὅπερ δ' ἀνθρώπου. τὸ αὐτὸ γὰρ ὅτι ἄνθρωπος,
τὸ δ' ὡς οὐ τὸ αὐτό.
Φανερὸν δ' ἐκ τούτων ὅτι οὐδὲ δοξάζειν ἅμα τὸ αὐτὸ
καὶ ἐπίστασθαι ἐνδέχεται. ἅμα γὰρ ἂν ἔχοι ὑπόληψιν τοῦ
1Since then rational intuition, science, and opinion, and what is revealed by these terms, are the only things that can be 'true', it follows that it is opinion that is concerned with that which may be true or false, and can be otherwise: opinion in fact is the grasp of a premiss which is immediate but not necessary. 5This view also fits the observed facts, for opinion is unstable, and so is the kind of being we have described as its object. Besides, when a man thinks a truth incapable of being otherwise he always thinks that he knows it, never that he opines it. He thinks that he opines when he thinks that a connexion, though actually so, may quite easily be otherwise; for he believes that such is the proper object of opinion, 10while the necessary is the object of knowledge.
In what sense, then, can the same thing be the object of both opinion and knowledge? And if any one chooses to maintain that all that he knows he can also opine, why should not opinion be knowledge? For he that knows and he that opines will follow the same train of thought through the same middle terms until the immediate premisses are reached; because it is possible to opine not only the fact but also the reasoned fact, and the reason is the middle term; 15so that, since the former knows, he that opines also has knowledge.
The truth perhaps is that if a man grasp truths that cannot be other than they are, in the way in which he grasps the definitions through which demonstrations take place, he will have not opinion but knowledge: if on the other hand he apprehends these attributes as inhering in their subjects, 20but not in virtue of the subjects' substance and essential nature possesses opinion and not genuine knowledge; and his opinion, if obtained through immediate premisses, will be both of the fact and of the reasoned fact; if not so obtained, of the fact alone. The object of opinion and knowledge is not quite identical; it is only in a sense identical, just as the object of true and false opinion is in a sense identical. The sense in which some maintain that true and false opinion can have the same object leads them to embrace many strange doctrines, particularly the doctrine that what a man opines falsely he does not opine at all. There are really many senses of 'identical', and in one sense the object of true and false opinion can be the same, in another it cannot. Thus, to have a true opinion that the diagonal is commensurate with the side would be absurd: but because the diagonal with which they are both concerned is the same, the two opinions have objects so far the same: on the other hand, as regards their essential definable nature these objects differ. 25The identity of the objects of knowledge and opinion is similar. Knowledge is the apprehension of, e.g. the attribute 'animal' as incapable of being otherwise, 35opinion the apprehension of 'animal' as capable of being otherwise-e.g. the apprehension that animal is an element in the essential nature of man is knowledge; the apprehension of animal as predicable of man but not as an element in man's essential nature is opinion: man is the subject in both judgements, but the mode of inherence differs.
In what sense, then, can the same thing be the object of both opinion and knowledge? And if any one chooses to maintain that all that he knows he can also opine, why should not opinion be knowledge? For he that knows and he that opines will follow the same train of thought through the same middle terms until the immediate premisses are reached; because it is possible to opine not only the fact but also the reasoned fact, and the reason is the middle term; 15so that, since the former knows, he that opines also has knowledge.
The truth perhaps is that if a man grasp truths that cannot be other than they are, in the way in which he grasps the definitions through which demonstrations take place, he will have not opinion but knowledge: if on the other hand he apprehends these attributes as inhering in their subjects, 20but not in virtue of the subjects' substance and essential nature possesses opinion and not genuine knowledge; and his opinion, if obtained through immediate premisses, will be both of the fact and of the reasoned fact; if not so obtained, of the fact alone. The object of opinion and knowledge is not quite identical; it is only in a sense identical, just as the object of true and false opinion is in a sense identical. The sense in which some maintain that true and false opinion can have the same object leads them to embrace many strange doctrines, particularly the doctrine that what a man opines falsely he does not opine at all. There are really many senses of 'identical', and in one sense the object of true and false opinion can be the same, in another it cannot. Thus, to have a true opinion that the diagonal is commensurate with the side would be absurd: but because the diagonal with which they are both concerned is the same, the two opinions have objects so far the same: on the other hand, as regards their essential definable nature these objects differ. 25The identity of the objects of knowledge and opinion is similar. Knowledge is the apprehension of, e.g. the attribute 'animal' as incapable of being otherwise, 35opinion the apprehension of 'animal' as capable of being otherwise-e.g. the apprehension that animal is an element in the essential nature of man is knowledge; the apprehension of animal as predicable of man but not as an element in man's essential nature is opinion: man is the subject in both judgements, but the mode of inherence differs.
89b
1 ἄλλως ἔχειν καὶ μὴ ἄλλως τὸ αὐτό· ὅπερ οὐκ ἐνδέχεται.
ἐν ἄλλῳ μὲν γὰρ ἑκάτερον εἶναι ἐνδέχεται τοῦ αὐτοῦ ὡς εἴρηται,
ἐν δὲ τῷ αὐτῷ οὐδ' οὕτως οἷόν τε· ἕξει γὰρ ὑπόληψιν
ἅμα, οἷον ὅτι ὁ ἄνθρωπος ὅπερ ζῷον (τοῦτο γὰρ ἦν τὸ
5 μὴ ἐνδέχεσθαι εἶναι μὴ ζῷον) καὶ μὴ ὅπερ ζῷον· τοῦτο γὰρ
ἔστω τὸ ἐνδέχεσθαι.
Τὰ δὲ λοιπὰ πῶς δεῖ διανεῖμαι ἐπί τε διανοίας καὶ
νοῦ καὶ ἐπιστήμης καὶ τέχνης καὶ φρονήσεως καὶ σοφίας,
τὰ μὲν φυσικῆς τὰ δὲ ἠθικῆς θεωρίας μᾶλλόν ἐστιν.
1This also shows that one cannot opine and know the same thing simultaneously; for then one would apprehend the same thing as both capable and incapable of being otherwise-an impossibility. Knowledge and opinion of the same thing can co-exist in two different people in the sense we have explained, but not simultaneously in the same person. That would involve a man's simultaneously apprehending, e.g. (1) that man is essentially animal-i.e. 5cannot be other than animal-and (2) that man is not essentially animal, that is, we may assume, may be other than animal.
Further consideration of modes of thinking and their distribution under the heads of discursive thought, intuition, science, art, practical wisdom, and metaphysical thinking, belongs rather partly to natural science, partly to moral philosophy.
Further consideration of modes of thinking and their distribution under the heads of discursive thought, intuition, science, art, practical wisdom, and metaphysical thinking, belongs rather partly to natural science, partly to moral philosophy.
Book 1,Chapter 34 (89b10–20)
10 Ἡ δ' ἀγχίνοιά ἐστιν εὐστοχία τις ἐν ἀσκέπτῳ χρόνῳ
τοῦ μέσου, οἷον εἴ τις ἰδὼν ὅτι ἡ σελήνη τὸ λαμπρὸν ἀεὶ ἔχει
πρὸς τὸν ἥλιον, ταχὺ ἐνενόησε διὰ τί τοῦτο, ὅτι διὰ τὸ λάμπειν
ἀπὸ τοῦ ἡλίου· ἢ διαλεγόμενον πλουσίῳ ἔγνω διότι δανείζεται·
ἢ διότι φίλοι, ὅτι ἐχθροὶ τοῦ αὐτοῦ. πάντα γὰρ
15 τὰ αἴτια τὰ μέσα [ὁ] ἰδὼν τὰ ἄκρα ἐγνώρισεν. τὸ λαμπρὸν
εἶναι τὸ πρὸς τὸν ἥλιον ἐφ' οὗ Α, τὸ λάμπειν ἀπὸ τοῦ ἡλίου
Β, σελήνη τὸ Γ. ὑπάρχει δὴ τῇ μὲν σελήνῃ τῷ Γ τὸ Β,
τὸ λάμπειν ἀπὸ τοῦ ἡλίου· τῷ δὲ Β τὸ Α, τὸ πρὸς τοῦτ'
εἶναι τὸ λαμπρόν, ἀφ' οὗ λάμπει· ὥστε καὶ τῷ Γ τὸ Α
20 διὰ τοῦ Β.
10Quick wit is a faculty of hitting upon the middle term instantaneously. It would be exemplified by a man who saw that the moon has her bright side always turned towards the sun, and quickly grasped the cause of this, namely that she borrows her light from him; or observed somebody in conversation with a man of wealth and divined that he was borrowing money, or that the friendship of these people sprang from a common enmity. In all these instances 15he has seen the major and minor terms and then grasped the causes, the middle terms.
Let A represent 'bright side turned sunward', B 'lighted from the sun', C the moon. Then B, 'lighted from the sun' is predicable of C, the moon, and A, 'having her bright side towards the source of her light', is predicable of B. So A is predicable of C 20through B.
----------------------------------------------------------------------
Let A represent 'bright side turned sunward', B 'lighted from the sun', C the moon. Then B, 'lighted from the sun' is predicable of C, the moon, and A, 'having her bright side towards the source of her light', is predicable of B. So A is predicable of C 20through B.
----------------------------------------------------------------------