§8.14#1Πρὸς δὲ γυμνασίαν καὶ μελέτην τῶν τοιούτων λόγων πρῶτον μὲν ἀντιστρέφειν ἐθίζεσθαι χρὴ τοὺς λόγους.
For the training and practice of such arguments, first of all, one must accustom oneself to reversing the arguments.
Ὅυτως γὰρ πρός τε τὸ λεγόμενον εὐπορώτερον ἕξομεν, καὶ ἐν ὀλίγοις πολλοὺς ἐξεπιστησόμεθα λόγους.
For in this way we shall have greater facility in dealing with what is said, and we shall know many arguments in a few.
Τὸ γὰρ ἀντιστρέφειν ἐστὶ τὸ μεταλαβόντα τὸ συμπέρασμα μετὰ τῶν λοιπῶν ἐρωτημάτων ἀνελεῖν ἓν τῶν δοθέντων· ἀνάγκη γάρ, εἰ τὸ συμπέρασμα μή ἐστι, μίαν τινὰ ἀναιρεῖσθαι τῶν προτάσεων, εἴπερ πασῶν τεθεισῶν ἀνάγκη ἦν τὸ συμπέρασμα εἶναι.
For to reverse is, having taken the conclusion in exchange, along with the remaining questions, to refute one of the given premises; for it is necessary, if the conclusion does not exist, that some one of the premises is refuted, if indeed when all were laid down it was necessary for the conclusion to exist.
Πρὸς ἅπασάν τε θέσιν, καὶ ὅτι οὕτως καὶ ὅτι οὐχ οὕτως, τὸ ἐπιχείρημα σκεπτέον, καὶ εὑρόντα τὴν λύσιν εὐθὺς ζητητέον· οὕτω γὰρ ἅμα συμβήσεται πρός τε τὸ ἐρωτᾶν καὶ πρὸς τὸ ἀποκρίνεσθαι γεγυμνάσθαι.
And for every thesis, both that it is so and that it is not so, one must examine the argument, and having found the solution, one must immediately seek it; for in this way it will happen that one is trained at the same time both for asking and for answering.
Κἂν πρὸς μηδένα ἄλλον ἔχωμεν, πρὸς αὑτούς.
And even if we have no one else, we must do it to ourselves.
Παράλληλά τε παραβάλλειν, ἐκλέγοντας πρὸς τὴν ἀντίθεσιν ἐπιχειρήματα· τοῦτο γὰρ πρός τε τὸ βιάζεσθαι πολλὴν εὐπορίαν ποιεῖ καὶ πρὸς τὸ ἐλέγχειν μεγάλην ἔχει βοήθειαν, ὅταν εὐπορῇ τις καὶ ὅτι οὕτως καὶ ὅτι οὐχ οὕτως· πρὸς τὰ ἐναντία γὰρ συμβαίνει ποιεῖσθαι τὴν φυλακήν.
And one must compare them side by side, selecting arguments for the opposition; for this produces great facility for forcing the opponent, and has great help for refutation, when one has facility both that it is so and that it is not so; for it happens that one keeps guard against contraries.
Πρός τε γνῶσιν καὶ τὴν κατὰ φιλοσοφίαν φρόνησιν τὸ δύνασθαι συνορᾶν καὶ συνεωρακέναι τὰ ἀφ᾿ ἑκατέρας συμβαίνοντα τῆς ὑποθέσεως οὐ μικρὸν ὄργανον· λοιπὸν γὰρ τούτων ὀρθῶς ἑλέσθαι θάτερον.
And for knowledge and the wisdom according to philosophy, to be able to see at a glance and to have seen what follows from each of the hypotheses is no small instrument; for what remains is to choose correctly one of these.
Δεῖ δὲ πρὸς τὸ τοιοῦτο ὑπάρχειν εὐφυᾶ· καὶ τοῦτ᾿ ἔστιν ἡ κατ᾿ ἀλήθειαν εὐφυΐα, τὸ δύνασθαι καλῶς ἑλέσθαι τἀληθὲς καὶ φυγεῖν τὸ ψεῦδος· ὅπερ οἱ πεφυκότες εὖ δύνανται ποιεῖν· εὖ γὰρ φιλοῦντες καὶ μισοῦντες τὸ προσφερόμενον εὖ κρίνουσι τὸ βέλτιστον.
And one must be naturally gifted for such a thing; and this is true natural gift, to be able to choose well the true and to flee the false; which those who are naturally gifted are well able to do; for by loving and hating well what is presented to them, they judge well what is best.
Πρός τε τὰ πλειστάκις ἐμπίπτοντα τῶν προβλημάτων ἐξεπίστασθαι δεῖ λόγους, καὶ μάλιστα περὶ τῶν πρώτων θέσεων· ἐν τούτοις γὰρ ἀποδυσπετοῦσιν οἱ ἀποκρινόμενοι πολλάκις.
And one must know thoroughly the arguments concerning the problems that occur most frequently, and especially concerning the first theses; for in these the answerers often lose heart and are at a loss.
Ἔτι τε ὅρων εὐπορεῖν δεῖ, καὶ τῶν ἐνδόξων τε καὶ τῶν πρώτων ἔχειν προχείρους· διὰ γὰρ τούτων οἱ συλλογισμοὶ γίνονται.
Further, one must be well provided with definitions, and have those that are accepted and the first ones ready at hand; for it is through these that deductions are made.
Πειρατέον δὲ καὶ εἰς ἃ πλειστάκις ἐμπίπτουσιν οἱ ἄλλοι λόγοι κατέχειν.
And one must try also to grasp those points into which the arguments of others most frequently fall.
Ὥσπερ γὰρ ἐν γεωμετρίᾳ πρὸ ἔργου τὸ περὶ τὰ στοιχεῖα γεγυμνάσθαι, καὶ ἐν ἀριθμοῖς τὸ περὶ τοὺς κεφαλισμοὺς προχείρως ἔχειν μέγα διαφέρει πρὸς τὸ καὶ τὸν ἄλλον ἀριθμὸν γινώσκειν πολλαπλασιούμενον, ὁμοίως καὶ ἐν τοῖς λόγοις τὸ πρόχειρον εἶναι περὶ τὰς ἀρχὰς καὶ τὰς προτάσεις ἀπὸ στόματος ἐξεπίστασθαι· καθάπερ γὰρ ἐν τῷ μνημονικῷ μόνον οἱ τόποι τεθέντες εὐθὺς ποιοῦσιν αὐτὰ μνημονεύειν, καὶ ταῦτα ποιήσει συλλογιστικώτερον διὰ τὸ πρὸς ὡρισμένας αὐτὰς βλέπειν κατ᾿ ἀριθμόν.
For just as in geometry it is useful to be trained in the elements, and in arithmetic to have mental calculations ready at hand makes a great difference to knowing also other numbers when multiplied, similarly also in arguments to be ready concerning the principles and to know the premises by heart is of great importance; for just as in the mnemonic art, the mere placing of the 'places' immediately makes them remember the things themselves, so also these things will make one more capable of reasoning, because of looking at them as determined in number.
Πρότασίν τε κοινὴν μᾶλλον ἢ λόγον εἰς μνήμην θετέον· ἀρχῆς γὰρ καὶ ὑποθέσεως εὐπορῆσαι μετρίως χαλεπόν.
And one must commit to memory a common premise rather than an argument; for to be well provided with a principle and a hypothesis is moderately difficult.