§1.13Τὰ μὲν οὖν γένη περὶ ὧν τε οἱ λόγοι καὶ ἐξ ὧν, καθάπερ ἔμπροσθεν εἴρηται, διωρίσθω· τὰ δ᾿ ὄργανα, δι᾿ ὧν εὐπορήσομεν τῶν συλλογισμῶν καὶ τῶν ἐπαγωγῶν, ἐστὶ τέτταρα, ἓν μὲν τὸ προτάσεις λαβεῖν, δεύτερον δὲ ποσαχῶς ἕκαστον λέγεται δύνασθαι διελεῖν, τρίτον τὰς διαφορὰς εὑρεῖν, τέταρτον δὲ ἡ τοῦ ὁμοίου σκέψις.
Let the classes of things, then, both about which arguments are concerned and from which they are constructed, be defined as has been said before; and the instruments by which we shall be well provided with deductions and inductions are four: one, the securing of propositions; second, to be able to distinguish in how many senses each expression is used; third, to find the differences; fourth, the investigation of similarity.
Ἔστι δὲ τρόπον τινὰ καὶ τὰ τρία τούτων προτάσεις· ἔστι γὰρ καθ᾿ ἕκαστον αὐτῶν ποιῆσαι πρότασιν, οἷον ὅτι αἱρετόν ἐστι τὸ καλὸν ἢ τὸ ἡδὺ ἢ τὸ συμφέρον, καὶ ὅτι διαφέρει αἴσθησις ἐπιστήμης τῷ τὴν μὲν ἀποβαλόντι δυνατὸν εἶναι πάλιν λαβεῖν, τὴν δ᾿ ἀδύνατον, καὶ ὅτι ὁμοίως ἔχει τὸ ὑγιεινὸν πρὸς ὑγίειαν καὶ τὸ εὐεκτικὸν πρὸς εὐεξίαν.
And in a way even three of these are propositions; for it is possible to make a proposition according to each of them, for example, that the honorable or the pleasant or the expedient is choice-worthy, and that perception differs from knowledge in that, for one who has lost the former, it is possible to regain it, but for the latter, impossible, and that the healthy stands in a similar relation to health as that which produces a good habit to a good habit.
Ἔστι δ᾿ ἡ μὲν πρώτη πρότασις ἀπὸ τοῦ πολλαχῶς λεγομένου, ἡ δὲ δευτέρα ἀπὸ τῶν διαφορῶν, ἡ δὲ τρίτη ἀπὸ τῶν ὁμοίων. §1.14Τὰς μὲν οὖν προτάσεις ἐκλεκτέον ὁσαχῶς διωρίσθη περὶ προτάσεως, ἢ τὰς πάντων δόξας προχειριζόμενον ἢ τὰς τῶν πλείστων ἢ τὰς τῶν σοφῶν, καὶ τούτων ἢ πάντων ἢ τῶν πλείστων ἢ τῶν γνωριμωτάτων, ἢ τὰς ἐναντίας ταῖς φαινομέναις, καὶ ὅσαι δόξαι κατὰ τέχνας εἰσίν.
And the first proposition is from that which is said in many ways, the second from the differences, and the third from similarities. Propositions, then, must be selected in as many ways as has been defined concerning the proposition, either by bringing forward the opinions of all, or those of the most, or those of the wise, and of these either of all, or of the most, or of the most well-known, or those contrary to what appears [to be the case], and all the opinions that are according to the arts.
Δεῖ δὲ προτείνειν καὶ τὰς ἐναντίας ταῖς φαινομέναις ἐνδόξοις κατ᾿ ἀντίφασιν, καθάπερ εἴρηται πρότερον.
And one must also propose, by contradiction, those contrary to opinions that appear to be generally accepted, as has been said before.
Χρήσιμον δὲ καὶ τὸ ποιεῖν αὐτὰς ἐν τῷ ἐκλέγειν μὴ μόνον τὰς οὔσας ἐνδόξους, ἀλλὰ καὶ τὰς ὁμοίας ταύταις, οἷον ὅτι τῶν ἐναντίων ἡ αὐτὴν αἴσθησις (καὶ γὰρ ἡ ἐπιστήμη) καὶ ὅτι ὁρῶμεν εἰσδεχόμενοί τι, οὐκ ἐκπέμποντες καὶ γὰρ καὶ ἐπὶ τῶν ἄλλων αἰσθήσεων οὕτως· ἀκούομέν τε γὰρ εἰσδεχόμενοί τι, οὐκ ἐκπέμποντες, καὶ γευόμεθα ὡσαύτως. Ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.
And it is also useful to make them, in selecting, not only those that are generally accepted, but also those similar to these, for example, that of contraries there is the same perception (for indeed [there is the same] knowledge), and that we see by receiving something, not by emitting (for indeed in the case of the other senses it is so; for we hear by receiving something, not by emitting, and we taste in the same way; and similarly in the case of the others).
Ἔτι ὅσα ἐπὶ πάντων ἢ τῶν πλείστων φαίνεται, ληπτέον ὡς ἀρχὴν καὶ δοκοῦσαν θέσιν· τιθέασι γὰρ οἱ μὴ συνορῶντες ἐπί τινος οὐχ᾿ οὕτως.
Further, whatever appears in all or in most cases must be taken as a principle and an accepted thesis; for those who do not see that in some case it is not so, posit it.
Ἐκλέγειν δὲ χρὴ καὶ ἐκ τῶν γεγραμμένων λόγων, τὰς δὲ διαγραφὰς ποιεῖσθαι περὶ ἑκάστου γένους ὑποτιθέντας χωρίς, οἷον περὶ ἀγαθοῦ ἢ περὶ ζῴου καὶ περὶ ἀγαθοῦ παντός, ἀρξάμενον ἀπὸ τοῦ τί ἐστιν.
And one should also select from written arguments, and make classifications concerning each genus, putting them down separately, for example, about "good" or about "animal" and about "every good", starting from "what it is".
Παρασημαίνεσθαι δὲ καὶ τὰς ἑκάστων δόξας, οἷον ὅτι Ἐμπεδοκλῆς τέτταρα ἔφησε τῶν σωμάτων στοιχεῖα εἶναι· θείη γὰρ ἄν τις τὸ ὑπό τινος εἰρημένον ἐνδόξου.
One should also note down the opinions of individual thinkers, for example, that Empedocles said there are four elements of bodies; for one would posit what has been said by someone well-known.
Ἔστι δ᾿ ὡς τύπῳ περιλαβεῖν τῶν προτάσεων καὶ τῶν προβλημάτων μέρη τρία. Αἱ μὲν γὰρ ἠθικαὶ προτάσεις εἰσίν, αἱ δὲ φυσικαί, αἱ δὲ λογικαί.
To grasp them in outline, then, there are three parts of propositions and problems: for some are ethical propositions, some physical, and some logical.
Ἠθικαὶ μὲν οὖν αἱ τοιαῦται, οἷον πότερον δεῖ τοῖς γονεῦσι μᾶλλον ἢ τοῖς νόμοις πειθαρχεῖν, ἐὰν διαφωνῶσιν· λογικαὶ δὲ οἷον πότερον τῶν ἐναντίων ἡ αὐτὴ ἐπιστήμη ἢ οὔ, φυσικαὶ δὲ οἷον πότερον ὁ κόσμος ἀΐδιος ἢ οὔ.
Ethical, then, are such as, for example, whether one ought to obey one's parents rather than the laws, if they disagree; logical, such as, for example, whether there is the same knowledge of contraries or not; and physical, such as, for example, whether the world is eternal or not.
Ὁμοίως δὲ καὶ τὰ προβλήματα.
And similarly also for problems.
Ποῖαι δ᾿ ἕκασται τῶν προειρημένων, ὁρισμῷ μὲν οὐκ εὐπετὲς ἀποδοῦναι περὶ αὐτῶν, τῇ δὲ διὰ τῆς ἐπαγωγῆς συνηθείᾳ πειρατέον γνωρίζειν ἑκάστην αὐτῶν, κατὰ τὰ προειρημένα παραδείγματα ἐπισκοποῦντα.
What kind each of the aforementioned is, is not easy to render by definition concerning them, but one must try to recognize each of them by the familiarity gained through induction, examining them according to the aforementioned examples.
Πρὸς μὲν οὖν φιλοσοφίαν κατ᾿ ἀλήθειαν περὶ αὐτῶν πραγματευτέον, διαλεκτικῶς δὲ πρὸς δόξαν.
With a view to philosophy, then, we must treat them according to truth, but dialectically with a view to opinion.
Ληπτέον δ᾿ ὅτι μάλιστα καθόλου πάσας τὰς προτάσεις, καὶ τὴν μίαν πολλὰς ποιητέον, οἷον ὅτι τῶν ἀντικειμένων ἡ αὐτὴ ἐπιστήμη, εἶθ᾿ ὅτι τῶν ἐναντίων καὶ ὅτι τῶν πρός τι.
And one must take all propositions as universal as possible, and make the single one many, for example, that there is the same knowledge of opposites, then that of contraries, and that of relatives.
Τὸν αὐτὸν δὲ τρόπον καὶ ταύτας πάλιν διαιρετέον, ἕως ἂν ἐνδέχηται διαιρεῖν, οἷον ὅτι ἀγαθοῦ καὶ κακοῦ, καὶ λευκοῦ καὶ μέλανος, καὶ ψυχροῦ καὶ θερμοῦ.
And in the same way these must be divided again as long as it is possible to divide, for example, that of good and bad, and of white and black, and of cold and hot.
Ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.
And similarly also for the others.