§1.2Ἑπόμενον δ᾿ ἂν εἴη τοῖς εἰρημένοις εἰπεῖν πρὸς πόσα τε καὶ τίνα χρήσιμος ἡ πραγματεία.
Following upon what has been said, it would be appropriate to state for how many and what purposes this treatise is useful.
Ἔστι δὴ πρὸς τρία, πρὸς γυμνασίαν, πρὸς τὰς ἐντεύξεις, πρὸς τὰς κατὰ φιλοσοφίαν ἐπιστήμας.
It is, indeed, for three: for mental training, for casual encounters, and for the sciences in accordance with philosophy.
Ὅτι μὲν οὖν πρὸς γυμνασίαν χρήσιμος, ἐξ αὐτῶν καταφανές ἐστι· μέθοδον γὰρ ἔχοντες ῥᾷον περὶ τοῦ προτεθέντος ἐπιχειρεῖν δυνησόμεθα.
That it is useful for training, then, is obvious from the facts themselves; for having a method, we shall be able more easily to argue about the proposed topic.
Πρὸς δὲ τὰς ἐντεύξεις, διότι τὰς τῶν πολλῶν κατηριθμημένοι δόξας οὐκ ἐκ τῶν ἀλλοτρίων ἀλλ᾿ ἐκ τῶν οἰκείων δογμάτων ὁμιλήσομεν πρὸς αὐτούς, μεταβιβάζοντες ὅ τι ἂν μὴ καλῶς φαίνωνται λέγειν ἡμῖν.
For casual encounters, because, having enumerated the opinions of the majority, we shall converse with them not from other people's dogmas but from their own, converting them from whatever they seem to us not to state correctly.
Πρὸς δὲ τὰς κατὰ φιλοσοφίαν ἐπιστήμας, ὅτι δυνάμενοι πρὸς ἀμφότερα διαπορῆσαι ῥᾷον ἐν ἑκάστοις κατοψόμεθα τἀληθές τε καὶ τὸ ψεῦδος.
For the sciences in accordance with philosophy, because, being able to raise difficulties on both sides, we shall more easily discern the true and the false in each.
Ἔτι δὲ πρὸς τὰ πρῶτα τῶν περὶ ἑκάστην ἐπιστήμην ἀρχῶν.
Further, it is useful for the primary elements of the principles concerning each science.
Ἐκ μὲν γὰρ τῶν οἰκείων τῶν κατὰ τὴν προτεθεῖσαν ἐπιστήμην ἀρχῶν ἀδύνατον εἰπεῖν τι περὶ αὐτῶν, ἐπειδὴ πρῶται αἱ ἀρχαὶ ἁπάντων εἰσί, διὰ δὲ τῶν περὶ ἕκαστα ἐνδόξων ἀνάγκη περὶ αὐτῶν διελθεῖν.
For from the principles peculiar to the proposed science, it is impossible to say anything about them, since the principles are primary of all; rather, it is necessary to discuss them through the reputable opinions concerning each.
Τοῦτο δ᾿ ἴδιον ἢ μάλιστα οἰκεῖον τῆς διαλεκτικῆς ἐστίν· ἐξεταστικὴ γὰρ οὖσα πρὸς τὰς ἁπασῶν τῶν μεθόδων ἀρχὰς ὁδὸν ἔχει.
This is peculiar or most appropriate to dialectic; for being investigative, it has a path toward the principles of all methods.
§1.3Ἕξομεν δὲ τελέως τὴν μέθοδον, ὅταν ὁμοίως ἔχωμεν ὥσπερ ἐπὶ ῥητορικῆς καὶ ἰατρικῆς καὶ τῶν τοιούτων δυνάμεων.
And we shall possess the method completely when we are in a similar state as in the case of rhetoric, medicine, and such capacities.
Τοῦτο δ᾿ ἐστὶ τὸ ἐκ τῶν ἐνδεχομένων ποιεῖν ἃ προαιρούμεθα.
This consists in doing what we choose from among the possibilities.
Οὔτε γὰρ ὁ ῥητορικὸς ἐκ παντὸς τρόπου πείσει, οὔθ᾿ ὁ ἰατρικὸς ὑγιάσει· ἀλλ᾿ ἐὰν τῶν ἐνδεχομένων μηδὲν παραλείπῃ, ἱκανῶς αὐτὸν ἔχειν τὴν ἐπιστήμην φήσομεν.
For neither will the rhetorician persuade by every means, nor will the physician heal; but if he omits none of the possibilities, we shall say that he possesses the science sufficiently.
§1.4Πρῶτον οὖν θεωρητέον ἐκ τίνων ἡ μέθοδος.
First, then, we must consider from what elements the method is composed.
Εἰ δὴ λάβοιμεν πρὸς πόσα καὶ ποῖα καὶ ἐκ τίνων οἱ λόγοι, καὶ πῶς τούτων εὐπορήσομεν, ἔχοιμεν ἂν ἱκανῶς τὸ προκείμενον.
If, indeed, we should grasp for how many and what kinds of things and from what elements arguments are, and how we shall have an abundance of these, we should sufficiently have our proposed goal.
Ἔστι δ᾿ ἀριθμῷ ἴσα καὶ ταὐτά, ἐξ ὧν τε οἱ λόγοι καὶ περὶ ὧν οἱ συλλογισμοί.
Now, those things from which arguments are and about which syllogisms are, are equal in number and the same.
Γίνονται μὲν γὰρ οἱ λόγοι ἐκ τῶν προτάσεων· περὶ ὧν δὲ οἱ συλλογισμοί, τὰ προβλήματά ἐστι.
For arguments arise from premises, while those things about which syllogisms are, are problems.
Πᾶσα δὲ πρότασις καὶ πᾶν πρόβλημα ἢ γένος ἢ ἴδιον ἢ συμβεβηκὸς δηλοῖ· καὶ γὰρ τὴν διαφορὰν ὡς οὖσαν γενικὴν ὁμοῦ τῷ γένει τακτέον.
And every premise and every problem indicates either a genus, a property, or an accident; for the difference, since it is generic, must be classified together with the genus.
Ἐπεὶ δὲ τοῦ ἰδίου τὸ μὲν τὸ τί ἦν εἶναι σημαίνει, τὸ δ᾿ οὐ σημαίνει, διῃρήσθω τὸ ἴδιον εἰς ἄμφω τὰ προειρημένα μέρη, καὶ καλείσθω τὸ μὲν τὸ τί ἦν εἶναι σημαῖνον ὅρος, τὸ δὲ λοιπὸν κατὰ τὴν κοινὴν περὶ αὐτῶν ἀποδοθεῖσαν ὀνομασίαν προσαγορευέσθω ἴδιον.
But since, of the property, one part signifies the essence, and the other does not, let the property be divided into both of the aforementioned parts, and let the one signifying the essence be called a definition, while the remainder let it be addressed as a property according to the common designation assigned to them.
Δῆλον οὖν ἐκ τῶν εἰρημένων ὅτι κατὰ τὴν νῦν διαίρεσιν τέτταρα τὰ πάντα συμβαίνει γίνεσθαι, ἢ ἴδιον ἢ ὅρον ἢ γένος ἢ συμβεβηκός.
It is clear, then, from what has been said, that according to the present division, it happens that all things in total become four: either a property, a definition, a genus, or an accident.
Μηδεὶς δ᾿ ἡμᾶς ὑπολάβῃ λέγειν ὡς ἕκαστον τούτων καθ᾿ αὑτὸ λεγόμενον πρότασις ἢ πρόβλημά ἐστιν, ἀλλ᾿ ὅτι ἀπὸ τούτων καὶ τὰ προβλήματα καὶ αἱ προτάσεις γίνονται.
But let no one suppose us to mean that each of these, when spoken of by itself, is a premise or a problem, but rather that from these both problems and premises arise.
Διαφέρει δὲ τὸ πρόβλημα καὶ ἡ πρότασις τῷ τρόπῳ.
And a problem and a premise differ in their turn.
Οὕτω μὲν γὰρ ῥηθέντος, ἆρά γε τὸ ζῷον πεζὸν δίπουν ὁρισμός ἐστιν ἀνθρώπου; καὶ ἆρά γε τὸ ζῷον γένος ἐστὶ τοῦ ἀνθρώπου; πρότασις γίνεται.
For if it is stated in this way: "Is 'two-footed pedestrian animal' the definition of man?" and "Is 'animal' the genus of man?", it becomes a premise.
Ἐὰν δέ, πότερον τὸ ζῷον πεζὸν δίπουν ὁρισμός ἐστιν ἀνθρώπου ἢ οὔ; καὶ πότερον τὸ ζῷον γένος ἐστίν; πρόβλημα γίνεται.
But if: "Whether 'two-footed pedestrian animal' is the definition of man or not?" and "Whether 'animal' is the genus?", it becomes a problem.
Ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.
Likewise also in the other cases.
Ὅστ᾿ εἰκότως ἴσα τῷ ἀριθμῷ τὰ προβλήματα καὶ αἱ προτάσεις εἰσίν. Ἀπὸ πάσης γὰρ προτάσεως πρόβλημα ποιήσεις μεταβάλλων τῷ τρόπῳ.
So that naturally problems and premises are equal in number; for from every premise you will make a problem by changing its turn.