Chapter 64

One should know that the purpose of the logical process is to make a clear statement of proof. The proof is a syllogism, and this syllogism is made up of two true premises and the conclusion. For example, if I want to prove that the soul is immortal, I say: ‘Everything that is perpetually in motion is immortal.’ This is a premise. Then I state a second premise: ‘The soul is perpetually in motion. Then the conclusion: ‘Therefore, the soul is immortal. Each part of the premise is called a term. A term is that into which every premise is resolved. For example, the premise goes: ‘Everything that is perpetually in motion is immortal. The part ‘everything, in so far as it is a part of the premise, is called a term. The ‘that is perpetually in motion is likewise called a term, as is the ‘immortal, and also the ‘is.

One should know that all the premises must be true and that the conclusion must follow from the premises. For, if one of the premises were found to be false, or the conclusion, then it would not be a syllogism, but a paralogism. Furthermore, there is the simple word, the noun, the verbal phrase, the statement, and the term. In respect to their subject, these five do not differ from one another. Their difference is only relative. ‘Man, for example, as a simple significant term, is called a simple word; as subject, it is called a noun; as fulfilling the functions of a predicate, it is called a verbal phrase; as part of an affirmation and negation, it is called statement; and as part of a premise and of a syllogism, it is called a term.

One should know that in the premise, that is, in the affirmation and negation, the subject is called a noun, whereas the predicate is called a verbal phrase. For example, ‘the man walks is an affirmation. ‘The man is the subject, and is called noun. ‘Walks fulfills the function of a predicate, and is called a verbal phrase. In ‘Socrates is noble the subject is ‘Socrates and it is called a noun. The phrase ‘is noble fulfills the function of a predicate, and, as a part of the affirmation, is called a verbal phrase. Even though grammarians call ‘noble a complementary word, yet, to put it simply, whatever accompanies the ‘is is a verbal phrase.

It should be known that there is no difference between the following five terms: statement, premise, question, objection, and conclusion. Thus, when I simply state that ‘the soul is immortal, this is called a statement. But when it is taken as a part of a syllogism, then to say that ‘the soul is immortal is to state a premise. And when someone objects to the premise by saying: ‘How is it evident that the soul is immortal?—then such is termed an objection. Again, when we proffer it as an inquiry: ‘Now, is the soul immortal?—this is called a question. When, finally, it has been deduced from the premises, it is called a conclusion. Take, for example, ‘the soul is perpetually in motion and ‘that which is perpetually in motion is immortal. From these premises it is deduced that ‘therefore the soul is immortal, and that is a conclusion.

[51] {Περὶ ὅρου καὶ προτάσεως καὶ συλλογισμοῦ.} Χρὴ γινώσκειν, ὅτι σκοπὸν ἔχει ἡ λογικὴ πραγματεία περὶ τῆς ἀποδείξεως. Ἡ δὲ ἀπόδειξις συλλογισμός ἐστιν: ὁ δὲ συλλογισμὸς σύγκειται ἐκ δύο ἀληθῶν προτάσεων καὶ τοῦ συμπεράσματος: οἷον θέλων ἀποδεῖξαι, ὅτι ἡ ψυχὴ ἀθάνατός ἐστι, λέγω, ὅτι πᾶν ἀεικίνητον ἀθάνατόν ἐστιν: αὕτη πρότασίς ἐστιν. Εἶτα λέγω καὶ δευτέραν πρότασιν: Ἡ ψυχὴ ἀεικίνητός ἐστιν: εἶτα τὸ συμπέρασμα: Ἡ ψυχὴ ἄρα ἀθάνατός ἐστιν. Ἑκάστη δὲ πρότασις ἐξ ὅρων σύγκειται, ἑκάστη γὰρ λέξις τῆς προτάσεως ὅρος λέγεται: ὅρος γάρ ἐστιν, εἰς ὃν ἀναλύεται ἡ πρότασις. Οἷον ἡ πρότασις λέγει: Πᾶν ἀεικίνητον ἀθάνατόν ἐστι: τὸ ‘Πᾶν’ ὅρος λέγεται ὡς μέρος προτάσεως καὶ τὸ ‘ἀεικίνητον’ ὁμοίως ὅρος λέγεται καὶ τὸ ‘ἀθάνατον’ ὅρος λέγεται καὶ τὸ ‘ἐστιν’ ὅρος λέγεται. Χρὴ γινώσκειν, ὅτι δεῖ τὰς προτάσεις ἀληθεῖς εἶναι καὶ τὸ συμπέρασμα ἀκολουθεῖν ταῖς προτάσεσιν. Εἰ γὰρ εὑρεθῇ ἡ μία τῶν προτάσεων ψευδὴς ἢ τὸ συμπέρασμα, παραλογισμός ἐστι καὶ οὐ συλλογισμός. Ἁπλῆ φωνή, ὄνομα, ῥῆμα, φάσις, ὅρος: ταῦτα τὰ πέντε κατὰ μὲν τὸ ὑποκείμενον οὐδὲν ἀλλήλων διαφέρουσι, μόνον δὲ κατὰ τὴν σχέσιν ἐστὶν αὐτῶν ἡ διαφορά: οἷον ἄνθρωπος ὡς μὲν ἁπλῶς σημαντικόν τινος λέγεται ἁπλῆ φωνή, ὡς δὲ ὑποκείμενον λέγεται ὄνομα, ὡς δὲ τάξιν ἐπέχον κατηγορουμένου λέγεται ῥῆμα, ὡς δὲ μέρος καταφάσεως ἢ ἀποφάσεως λέγεται φάσις, ὡς δὲ μέρος προτάσεως καὶ συλλογισμοῦ λέγεται ὅρος. Χρὴ δὲ γινώσκειν, ὅτι ἐν τῇ προτάσει ἤτοι τῇ καταφάσει καὶ ἀποφάσει τὸ μὲν ὑποκείμενον ὄνομα λέγεται, τὸ δὲ κατηγορούμενον λέγεται ῥῆμα. Οἷον κατάφασίς ἐστιν: Ἄνθρωπος περιπατεῖ, τὸ ‘ἄνθρωπος’ ὑποκείμενόν ἐστι καὶ λέγεται ὄνομα, τὸ ‘περιπατεῖ’ τάξιν ἐπέχει κατηγορουμένου καὶ λέγεται ῥῆμα: ‘Σωκράτης καλός ἐστι’, τὸ ‘Σωκράτης’ ὑποκείμενόν ἐστι καὶ λέγεται ὄνομα, τὸ ‘καλός ἐστι’ τάξιν ἐπέχει κατηγορουμένου καὶ λέγεται ῥῆμα ὡς μέρος καταφάσεως, εἰ καὶ παρὰ τοῖς γραμματικοῖς ὄνομα λέγεται τὸ ‘καλός’. Καὶ ἁπλῶς, ᾧτινι ἀκολουθεῖ τὸ ‘ἐστι’, ῥῆμά ἐστι καὶ ἐν τῇ ἀποφάσει καὶ ἐν τῇ καταφάσει, κἂν ὄνομά ἐστι κἂν ῥῆμα, ῥῆμα λέγεται παρὰ τοῖς φιλοσόφοις ὡς κατηγορούμενον. Ἰστέον, ὅτι τὰ πέντε ταῦτα οὐδὲν ἀλλήλων διενηνόχασιν, ἀπόφανσις, πρότασις, πρόβλημα, ἔνστασις, συμπέρασμα. Ὅταν γὰρ ἁπλῶς ἀποφαίνωμαι, ὅτι ἡ ψυχὴ ἀθάνατός ἐστιν, ἀπόφανσις λέγεται. Ὅταν δὲ ὡς μέρος συλλογισμοῦ ληφθῇ, τότε πρότασίς ἐστιν τὸ λέγειν: Ἡ ψυχὴ ἀθάνατός ἐστιν. Ἡνίκα δέ τις ἐνίσταται πρὸς τὴν πρότασιν λέγων: Πόθεν δῆλον, ὅτι ἡ ψυχὴ ἀθάνατός ἐστι; τότε τὸ τοιοῦτον ἔνστασις προσαγορεύεται. Ἡνίκα δὲ πάλιν προτείνομεν εἰς ζήτησιν: Ἆρα ἡ ψυχὴ ἀθάνατός ἐστι; καλεῖται πρόβλημα. Ὅτε δὲ ἐκ προτάσεως συναχθῇ, καλεῖται συμπέρασμα, οἷον: Ἡ ψυχὴ ἀεικίνητός ἐστι, τὸ ἀεικίνητον ἀθάνατον, ἐκ τῶν προτάσεων τούτων συνάγεται: Ἄρα ἡ ψυχὴ ἀθάνατός ἐστι: τοῦτό ἐστι συμπέρασμα.