I. Πρῶτον εἰπεῖν περὶ τί καὶ τίνος ἐστὶν ἡ σκέψις, ὅτι περὶ ἀπόδειξιν καὶ ἐπιστήμης ἀποδεικτικῆς· εἶτα διορίσαι τί ἐστι πρότασις καὶ τί ὅρος καὶ τί συλλογισμός, καὶ ποῖος τέλειος καὶ ποῖος ἀτελής, μετὰ δὲ ταῦτα τί τὸ ἐν ὅλῳ εἶναι ἢ μὴ εἶναι τόδε 15τῷδε, καὶ τί λέγομεν τὸ κατὰ παντὸς ἢ μηδενὸς κατηγορεῖσθαι.
Πρότασις μὲν οὖν ἐστι λόγος καταφατικὸς ἢ ἀποφατικὸς τινὸς κατά τινος· οὗτος δὲ ἢ καθόλου ἢ ἐν μέρει ἢ ἀδιόριστος. λέγω δὲ καθόλου μὲν τὸ παντὶ ἢ μηδενὶ ὑπάρχειν, ἐν μέρει δὲ τὸ τινὶ ἢ μὴ 20τινὶ ἢ μὴ παντὶ ὑπάρχειν, ἀδιόριστον δὲ τὸ ὑπάρχειν ἢ μὴ ὑπάρχειν ἄνευ τοῦ καθόλου ἢ κατὰ μέρος, οἷον τὸ τῶν ἐναντίων εἶναι τὴν αὐτὴν ἐπιστήμην ἢ τὸ τὴν ἡδονὴν μὴ εἶναι ἀγαθόν.
Διαφέρει δὲ ἡ ἀποδεικτικὴ πρότασις τῆς διαλεκτικῆς, ὅτι ἡ μὲν ἀποδεικτικὴ λῆψις θατέρου μορίου τῆς ἀντιφάσεώς ἐστιν (οὐ γὰρ ἐρωτᾷ ἀλλὰ
I. Our first duty is to state the scope of our inquiry, Book I. The Laws of Syllogism. Scope of the treatise. and to what science it pertains: that it is concerned with demonstration, and pertains to a demonstrative science. Next we must define the meaning of ‘premiss’ and ‘term’ and ‘syllogism,’ and distinguish between a perfect and an imperfect syllogism; and after this we must explain in what sense one term is said to be or not to be ‘wholly contained’ in another; and what we mean by ‘predicated of all’ o ‘of none.’
A premiss is an affirmative or negative statement Preliminary definition of the premises, and its types. of something about some subject. This statement may be universal or particular or indefinite. By universal I mean a statement which applies to all, or to none, of the subject; by particular, a statement which applies to some of the subject, or does not apply to some, or does not apply to all; by indefinite, a statement which applies or does not apply without reference to universality or particularity, e.g., ‘contraries are studied by the same science’ or ‘pleasure is not good.’
The premiss of demonstration differs from the Demonstrative, dialectical and syllogistic premisses. premiss of dialectic in that the former is the assumption of one member of a pair of contradictory statements (since the demonstrator does not ask a question