Authors/Aristotle/priora/Liber 1/C25

Chapter 25

Greek	Latin	English
	(PL 64 0667A) CAPUT XXV. De numero terminorum syllogismi.	25
41b36 Δῆλον δὲ καὶ ὅτι πᾶσα ἀπόδειξις ἔσται διὰ τριῶν ὅρων καὶ οὐ πλειόνων, ἐὰν μὴ δι᾽ ἄλλων καὶ ἄλλων τὸ αὐτὸ συμπέρασμα γίνηται, οἷον τὸ Ε διά τε τῶν Α Β καὶ διὰ τῶν Γ Δ, ἢ διὰ τῶν Α Β καὶ Α Γ Δ· πλείω γὰρ μέσα τῶν αὐτῶν οὐδὲν εἶναι κωλύει. τούτων δ᾽ ὄντων οὐχ εἷς ἀλλὰ ↵ πλείους εἰσὶν οἱ συλλογισμοί. ἢ πάλιν ὅταν ἑκάτερον τῶν Α Β διὰ συλλογισμοῦ ληφθῆι (οἷον τὸ Α διὰ τῶν Δ Ε καὶ πάλιν τὸ Β διὰ τῶν Ζ Θ), ἢ τὸ μὲν ἐπαγωγῆι, τὸ δὲ συλλογισμῶι. ἀλλὰ καὶ οὕτως πλείους οἱ συλλογισμοί· πλείω γὰρ τὰ συμπεράσματα ἐστιν, οἷον τό τε Α καὶ τὸ Β καὶ τὸ Γ.	(0667B) Palam autem et quoniam omnis demonstratio erit per tres terminos, et non per plures, nisi per alia et alia eadem conclusio fiat, ut E per A B, et per C D, aut per A B, et A C, et B C, plura enim media eorumdem nihil esse prohibet, haec autem cum sint, non unus, sed plures sunt syllogismi. (0667C) Aut rursum, quando utrumque A B sumitur per syllogismum, ut A per D E, et rursum B per F G, aut hoc quidem inductione, illud autem syllogismo, sed et si plures erunt syllogismi, plures enim conclusiones sunt, ut A B et C.	It is clear too that every demonstration will proceed through three terms and no more, unless the same conclusion is established by different pairs of propositions; e.g. the conclusion E may be established through the propositions A and B, and through the propositions C and D, or through the propositions A and B, or A and C, or B and C. For nothing prevents there being several middles for the same terms. But in that case there is not one but several syllogisms. Or again when each of the propositions A and B is obtained by syllogistic inference, e.g. by means of D and E, and again B by means of F and G. Or one may be obtained by syllogistic, the other by inductive inference. But thus also the syllogisms are many; for the conclusions are many, e.g. A and B and C.
Εἰ δ᾽ οὖν μὴ πλείους ἀλλ᾽ εἷς, οὕτω μὲν ἐνδέχεται γενέσθαι διὰ πλειόνων τὸ αὐτὸ συμπέρασμα, ὡς δὲ τὸ Γ διὰ τῶν Α Β, ἀδύνατον. ἔστω γὰρ τὸ Ε συμπεπερασμένον ἐκ τῶν Α Β Γ Δ. οὐκοῦν ἀνάγκη τι αὐτῶν ἄλλο πρὸς ἄλλο εἰλῆφθαι, τὸ μὲν ὡς ὅλον τὸ δ᾽ ὡς μέρος· τοῦτο γὰρ δέδεικται πρότερον, ὅτι ὄντος συλλογισμοῦ ἀναγκαῖον οὕτως τινὰς ἔχειν τῶν ὅρων. ἐχέτω οὖν τὸ Α οὕτως πρὸς τὸ Β. ἔστιν ἄρα τι ἐξ αὐτῶν συμπέρασμα. οὐκοῦν ἤτοι τὸ Ε ἢ τῶν Γ Δ θάτερον ἢ ἄλλο τι παρὰ ταῦτα.	Si igitur non plures, sed unus (sic autem contingit fieri per plura media eamdem conclusionem, ut E quidem per A B C D ), impossibile. Sit enim E conclusio ex A B C D, ergo necesse est aliquid eorum, aliud ad aliud sumptum esse, hoc quidem ut totum, illud vero ut pars, hoc enim ostensum est prius, quoniam si est syllogismus, necesse est sic aliquos se habere terminorum. Habeat se ergo A sic ad B, est itaque aliqua ex eis conclusio, aut ergo E, aut alterum eorum quae sunt C D, aut alterum aliud quidem praeter haec.	But if this can be called one syllogism, not many, the same conclusion may be reached by more than three terms in this way, but it cannot be reached as C is established by means of A and B. Suppose that the proposition E is inferred from the premisses A, B, C, and D. It is necessary then that of these one should be related to another as whole to part: for it has already been proved that if a syllogism is formed some of its terms must be related in this way. Suppose then that A stands in this relation to B. Some conclusion then follows from them. It must either be E or one or other of C and D, or something other than these.
καὶ εἰ μὲν τὸ Ε, ἐκ τῶν Α Β μό νον ἂν εἴη ὁ συλλογισμός. τὰ δὲ Γ Δ εἰ μὲν ἔχει οὕτως ὥστ᾽ εἶναι τὸ μὲν ὡς ὅλον τὸ δ᾽ ὡς μέρος, ἔσται τι καὶ ἐξ ἐκείνων, καὶ ἤτοι τὸ Ε ἢ τῶν Α Β θάτερον ἢ ἄλλο τι παρὰ ταῦτα.	Et si E quidem, ex A B tantum, erit syllogismus, C D autem quidem se habeant sic ut sit hoc quidem ut notum, illud vero ut pars, erit aliquid ex illis aut E, aut aliquid eorum quae sunt A B, aut alterum aliud quidem praeter haec.	(1) If it is E the syllogism will have A and B for its sole premisses. But if C and D are so related that one is whole, the other part, some conclusion will follow from them also; and it must be either E, or one or other of the propositions A and B, or something other than these.
καὶ εἰ μὲν τὸ Ε ἢ τῶν Α Β θάτερον, ἢ πλείους ἔσονται οἱ συλλογισμοί, ἢ ὡς ἐνεδέχετο ταὐτὸ διὰ πλειόνων ὅρων περαίνεσθαι συμβαίνει· εἰ δ᾽ ἄλλο τι παρὰ ταῦτα, πλείους ἔσονται καὶ ἀσύναπτοι οἱ συλλογισμοὶ πρὸς ἀλλήλους. εἰ δὲ μὴ οὕτως ἔχοι τὸ Γ πρὸς τὸ Δ ὥστε ποιεῖν συλλογισμόν, μάτην ἔσται εἰλημμένα, εἰ μὴ ἐπαγωγῆς ἢ κρύψεως ἤ τινος ἄλλου τῶν τοιούτων χάριν.	Et si E quidem, aut eorum quae sunt A B alterum, aut plures erunt syllogismi, aut (ut contingebat) idem per plures terminos concludi accidit, si autem aliud quidem praeter haec, plures erunt et inconiuncti syllogismi ad invicem, si autem non sic se habeat C ad D ut faciat syllogismum, vane erunt sumpta, nisi inductionis, aut celationis, aut alicuius alius talium gratia.	And if it is (i) E, or (ii) A or B, either (i) the syllogisms will be more than one, or (ii) the same thing happens to be inferred by means of several terms only in the sense which we saw to be possible. But if (iii) the conclusion is other than E or A or B, the syllogisms will be many, and unconnected with one another. But if C is not so related to D as to make a syllogism, the propositions will have been assumed to no purpose, unless for the sake of induction or of obscuring the argument or something of the sort.
Εἰ δ᾽ ἐκ τῶν Α Β μὴ τὸ Ε ἀλλ᾽ ἄλλο τι γίγνεται συμπέρασμα, ἐκ δὲ τῶν Γ Δ ἢ τούτων θάτερον ἢ ἄλλο παρὰ ταῦτα, πλείους τε οἱ συλλογισμοὶ γίνονται καὶ οὐ τοῦ ὑποκειμένου· ὑπέκειτο γὰρ εἶναι τοῦ Ε τὸν συλλογισμόν.	(0667D) Si autem ex A B non E, sed alia quaedam fiat conclusio, ex C D autem aut horum alterum, aut aliud praeter haec, et plures fiunt syllogismi, et non eius quod positum est. Ponebatur enim eius quod est E esse syllogismum.	(2) But if from the propositions A and B there follows not E but some other conclusion, and if from C and D either A or B follows or something else, then there are several syllogisms, and they do not establish the conclusion proposed: for we assumed that the syllogism proved E.
Εἰ δὲ μὴ γίνεται ἐκ τῶν Γ Δ μηδὲν συμπέρασμα, μάτην τε εἰλῆφθαι αὐτὰ συμβαίνει καὶ μὴ τοῦ ἐξ ἀρχῆς εἶναι τὸν συλλογισμόν.	Si autem non fiat ex C D nulla conclusio, et vane sumpta esse ea accidit, et non eius quod est ex principio esse syllogismum.	And if no conclusion follows from C and D, it turns out that these propositions have been assumed to no purpose, and the syllogism does not prove the original proposition.
ὥστε φανερὸν ὅτι πᾶσα ἀπόδειξις καὶ πᾶς συλλογισμὸς ἔσται διὰ τριῶν ὅρων μόνον.	Quare manifestum quoniam omnis demonstratio et omnis syllogismus erit per tres terminos solos.	So it is clear that every demonstration and every syllogism will proceed through three terms only.
	(PL 64 0667D) CAPUT XXVI. De numero propositionum et prosyllogismis.
Τούτου δ᾽ ὄντος φανεροῦ, δῆλον ὡς καὶ ἐκ δύο προτάσεων καὶ οὐ πλειόνων (οἱ γὰρ τρεῖς ὅροι δύο προτάσεισ), εἰ μὴ προσλαμβάνοιτό τι, καθάπερ ἐν τοῖς ἐξ ἀρχῆς ἐλέχθη, πρὸς τὴν τελείωσιν τῶν συλλογισμῶν. φανερὸν οὖν ὡς ἐν ὧι λόγωι συλλογιστικῶι μὴ ἄρτιαί εἰσιν αἱ προτάσεις δι᾽ ὧν γίνεται τὸ συμπέρασμα τὸ κύριον (ἔνια γὰρ τῶν ἄνωθεν συμπερασμάτων ἀναγκαῖον εἶναι προτάσεισ), οὗτος ὁ λόγος ἢ οὐ συλλελόγισται ἢ πλείω τῶν ἀναγκαίων ἠρώτηκε πρὸς τὴν θέσιν.	(0668A) Hoc autem manifesto, palam quoniam et ex duabus propositionibus, et non pluribus, nam tres termini, duae sunt propositiones, nisi assumatur aliquid (quemadmodum in prioribus dictum est) ad perfectionem syllogismorum. Manifestum igitur quando, ut in oratione syllogistica, non pares sunt propositiones per quas fit conclusio principalis (quasdam enim superiorum conclusionum necessarium est esse propositiones), haec oratio aut non syllogistica est, aut plura necessariis interrogavit ad positionem.	This being evident, it is clear that a syllogistic conclusion follows from two premisses and not from more than two. For the three terms make two premisses, unless a new premiss is assumed, as was said at the beginning, to perfect the syllogisms. It is clear therefore that in whatever syllogistic argument the premisses through which the main conclusion follows (for some of the preceding conclusions must be premisses) are not even in number, this argument either has not been drawn syllogistically or it has assumed more than was necessary to establish its thesis.
↵ Κατὰ μὲν οὖν τὰς κυρίας προτάσεις λαμβανομένων τῶν συλλογισμῶν, ἅπας ἔσται συλλογισμὸς ἐκ προτάσεων μὲν ἀρτίων ἐξ ὅρων δὲ περιττῶν· ἑνὶ γὰρ πλείους οἱ ὅροι τῶν προτάσεων. ἔσται δὲ καὶ τὰ συμπεράσματα ἡμίση τῶν προ τάσεων.	Secundum igitur principales propositiones sumptis syllogismis, omnis syllogismus erit ex propositionibus quidem perfectis, ex terminis autem abundantibus, uno enim plures termini propositionibus, erunt autem et conclusiones dimidietas propositionum.	If then syllogisms are taken with respect to their main premisses, every syllogism will consist of an even number of premisses and an odd number of terms (for the terms exceed the premisses by one), and the conclusions will be half the number of the premisses.
ὅταν δὲ διὰ προσυλλογισμῶν περαίνηται ἢ διὰ πλειόνων μέσων συνεχῶν, οἷον τὸ Α Β διὰ τῶν Γ Δ, τὸ μὲν πλῆθος τῶν ὅρων ὡσαύτως ἑνὶ ὑπερέξει τὰς προτάσεις (ἢ γὰρ ἔξωθεν ἢ εἰς τὸ μέσον τεθήσεται ὁ παρεμπίπτων ὅρος· ἀμφοτέρως δὲ συμβαίνει ἑνὶ ἐλάττω εἶναι τὰ διαστήματα τῶν ὅρων), αἱ δὲ προτάσεις ἴσαι τοῖς διαστήμασιν·	(0668B) Quando autem per prosyllogismos concluditur, aut per plura media non continua, ut A B per C D, multitudo quidem terminorum similiter uno superabit propositiones, aut enim extrinsecus, aut medium ponetur intercidens terminus, utrinque autem accidit uno minus esse intervalla quam terminos, propositiones autem aequales sunt intervallis.	But whenever a conclusion is reached by means of prosyllogisms or by means of several continuous middle terms, e.g. the proposition AB by means of the middle terms C and D, the number of the terms will similarly exceed that of the premisses by one (for the extra term must either be added outside or inserted: but in either case it follows that the relations of predication are one fewer than the terms related), and the premisses will be equal in number to the relations of predication.
οὐ μέντοι αἰεὶ αἱ μὲν ἄρτιαι ἔσονται οἱ δὲ περιττοί, ἀλλ᾽ ἐναλλάξ, ὅταν μὲν αἱ προτάσεις ἄρτιαι, περιττοὶ οἱ ὅροι, ὅταν δ᾽ οἱ ὅροι ἄρτιοι, περιτταὶ αἱ προτάσεις· ἅμα γὰρ τῶι ὅρωι μία προστίθεται πρότασις, ἂν ὁποθενοῦν προστεθῆι ὁ ὅρος, ὥστ᾽ ἐπεὶ αἱ μὲν ἄρτιαι οἱ δὲ περιττοὶ ἦσαν, ἀνάγκη παραλλάττειν τῆς αὐτῆς προσθέσεως γινομένης.	Non tamen hae quidem semper perfectae erunt, illi vero abundantes, sed permutatim, quia cum propositiones quidem sunt perfectae, abundantes erunt termini, cum vero termini perfecti, abundantes erunt propositiones, simul enim termino addito, una additur propositio, undecunque addatur terminus. Quare quoniam hae propositiones quidem perfectae, illi vero abundantes erant, necesse est transmutare eadem, additione facta.	The premisses however will not always be even, the terms odd; but they will alternate-when the premisses are even, the terms must be odd; when the terms are even, the premisses must be odd: for along with one term one premiss is added, if a term is added from any quarter. Consequently since the premisses were (as we saw) even, and the terms odd, we must make them alternately even and odd at each addition.
τὰ δὲ συμπεράσματα οὐκέτι τὴν αὐτὴν ἕξει τάξιν οὔτε πρὸς τοὺς ὅρους οὔτε πρὸς τὰς προτάσεις· ἑνὸς γὰρ ὅρου προστιθεμένου συμπεράσματα προστεθήσεται ἑνὶ ἐλάττω τῶν προϋπαρχόντων ὅρων· πρὸς μόνον γὰρ τὸν ἔσχατον οὐ ποιεῖ συμπέρασμα, πρὸς δὲ τοὺς ἄλλους πάντας, οἷον εἰ τῶι Α Β Γ πρόσκειται τὸ Δ, εὐθὺς καὶ συμπεράσματα δύο πρόσκειται, τό τε πρὸς τὸ Α καὶ τὸ πρὸς τὸ Β. ὁμοίως δὲ κἀπὶ τῶν ἄλλων. κἂν εἰς τὸ μέσον δὲ παρεμπίπτηι, τὸν αὐτὸν τρόπον· πρὸς ἕνα γὰρ μόνον οὐ ποιήσει συλλογισμόν. ὥστε πολὺ πλείω τὰ συμπεράσματα καὶ τῶν ὅρων ἔσται καὶ τῶν προτάσεων.	(0668C) Conclusiones autem non etiam eum habebunt ordinem neque ad terminos, neque ad propositiones, uno enim termino addito, conclusiones adiungentur uno, pauciores praeexistentibus terminis, ad solum enim ultimum non facit conclusionem, ad alios autem omnes. Ut si eis quae sunt A B C, adiacet D, statim et conclusiones duae adiacent, quae ad A, et ad B, similiter autem et in aliis. Si autem ad medium intercidat, eodem modo, ad unum enim solum non faciet syllogismum, quare multo plures conclusiones erunt et terminis et propositionibus.	But the conclusions will not follow the same arrangement either in respect to the terms or to the premisses. For if one term is added, conclusions will be added less by one than the pre-existing terms: for the conclusion is drawn not in relation to the single term last added, but in relation to all the rest, e.g. if to ABC the term D is added, two conclusions are thereby added, one in relation to A, the other in relation to B. Similarly with any further additions. And similarly too if the term is inserted in the middle: for in relation to one term only, a syllogism will not be constructed. Consequently the conclusions will be much more numerous than the terms or the premisses.