[146] Topic. III. vi. p. 119, b. 31-p. 120, a. 5.
Suppose the respondent to propound his thesis indefinitely, not carrying the indication either of universal or particular; e.g., Pleasure is good. This can be proved by showing either that all pleasure is good, or that some pleasure is good; while it can be refuted only through the universal negative — by showing that no pleasure is good.[147] But, if the thesis be divested of its indefinite character and propounded either as universal or as particular, there will then be two distinct ways of refuting it. If it be farther specialized — e.g., One pleasure only is good — there will be three ways of refuting: you may show either that all pleasures are good; or that no pleasure is good; or that more pleasures than one are good. If the proposition be specialized farther still — e.g., Prudence alone among all the virtues is science, — there are four lines of argument open for refuting it: you may prove either that all virtue is science; or that no virtue is science; or that some other virtue (such as justice) is science; or that prudence is not science.[148]
[147] Ibid. p. 120, a. 6-20: ἀδιορίστου μὲν οὖν ὄντος τοῦ προβλήματος μοναχῶς ἀνασκευάζειν ἐνδέχεται — ἀναιρεῖν μὲν μοναχῶς ἐνδέχεται, κατασκευάζειν δὲ διχῶς. &c.
[148] Ibid. a. 15-31.
In dealing with a particular proposition as thesis, still other loci already indicated for dealing with universal propositions will be available. You will run through the particulars comprised in the subject, distributed into genera and species. When you have produced a number of particulars successively to establish the universal, affirmative or negative, you are warranted in calling on the respondent either to admit the universal, or to produce on his side some adverse particular.[149] You will also (as was before recommended) distribute the predicate of the thesis into the various species which it comprehends. If no one of these species be truly affirmable of the subject, then neither can the genus be truly affirmable; so that you will have refuted the thesis, supposing it to be affirmative. If, on the contrary, any one of the species be truly affirmable of the subject, then the genus will also be truly affirmable; so that you will have refuted the thesis, supposing it to be negative. Thus, if the thesis propounded be, The soul is a number: you divide number into its two species, odd and even, and prove that the soul is neither odd nor even; wherefore, it is not a number.[150]
[149] Ibid. a. 32-38: ἄν τε γὰρ παντὶ φαίνηται ὑπάρχον ἄν τε μηδενί, πολλὰ προενέγκαντι ἀξιωτέον καθόλου ὁμολογεῖν, ἢ φέρειν ἔνστασιν ἐπὶ τίνος οὐχ οὕτως.
[150] Topic. III. vi. p. 120, a. 37-b. 6. It would appear from the examples here given by Aristotle — ὁ χρόνος οὐ κινεῖται, ὁ χρόνος οὔκ ἐστι κίνησις, ἡ ψυχὴ οὔκ ἐστιν ἀριθμός, that he considers these propositions as either indefinite or particular.
IV.
After this long catalogue of Loci belonging to debate on propositions of Accident, Aristotle proceeds to enumerate those applicable to propositions of Genus and of Proprium. Neither Genus nor Proprium is often made subject of debate as such; but both of them are constituent elements of the debate respecting Definition, which is of frequent occurrence.[151] For that reason, both deserve to be studied.
[151] Ibid. IV. i. p. 120, b. 12: μετὰ δὲ ταῦτα περὶ τῶν πρὸς τὸ γένος καὶ τὸ ἴδιον ἐπισκεπτέον· ἔστι δὲ ταῦτα στοιχεῖα τῶν πρὸς τοὺς ὅρους· περὶ αὐτῶν δὲ τούτων ὀλιγάκις αἱ σκέψεις γίνονται τοῖς διαλεγομένοις.