[357] Ibid. a. 32-b. 12.
So much greater are the difficulties belonging to the defence of a Definition, as compared with the attack upon it; and the same may be said about attack and defence of a Proprium, and of a Genus. In both cases, the assailant will carry his point, if he can show that the predicate in question is not predicable, in this relation, of all, or that it is not predicable, in this relation, of any one. But the defendant is required to make good the universal against every separate objection advanced against any one of the particulars. It is a general rule, that the work of destruction is easier than that of construction; and the present cases come under that rule.[358] The hardest of all theses to defend, and the easiest to overthrow, is where Definition is affirmed; for the respondent in this case is required to declare well the essence of his subject, and he stands in need of the greatest number of auxiliary data; while all the Loci for attack, even those properly belonging to the Proprium, the Genus, and the Accident, are available against him.[359] Next in order, as regards difficulty of defence, comes the theses affirming Proprium; where the respondent has to make out, not merely that the predicate belongs to the subject, but that it belongs thereunto exclusively and reciprocally: here also all the Loci for attack, even those properly belonging to Accident, are available.[360] Easiest of all theses to defend, while it is the hardest to impugn, is that in which Accident alone is affirmed — the naked fact, that the predicate A belongs to the Subject B, without investing it with the character either of Genus or Proprium. Here what is affirmed is a minimum, requiring the smallest array of data to be conceded; moreover, the Loci available for attack are the fewest, since many of those which may be employed against Genus, Proprium, and Definition, have no application against a thesis affirming merely Accident.[361] Indeed, if the thesis affirmed be only a proposition particular (and not universal), affirming Accident (and nothing more), the task of refuting it will be more difficult than that of maintaining it.[362]
[358] Ibid. b. 13-32. ἔοικε δ’, ὥσπερ καὶ ἐν τοῖς ἄλλοις τὸ διαφθεῖραι τοῖ ποιῆσαι ῥᾷον, οὕτω καὶ ἐπὶ τούτων τὸ ἀνασκευάσαι τοῦ κατασκευάσαι.
[359] Topic. VII. v. p. 155, a. 3-21: φανερὸν δὲ καὶ διότι πάντων ῥᾷστον ὅρον ἀνασκευάσαι.
[360] Ibid. a. 23-27. Aristotle has in view the most complete Proprium: belonging omni, soli, et semper.
[361] Ibid. a. 28-36: ῥᾷστον δὲ πάντων κατασκευάσαι τὸ συμβεβηκός· — ἀνασκευάζειν δὲ χαλεπώτατον τὸ συμβεβηκός, ὅτι ἐλάχιστα ἐν αὐτῷ δέδοται, &c.
[362] Ibid. p. 154, b. 36-p. 155, a. 2: τὸ δ’ ἐπὶ μέρους ἀνάπαλιν ῥᾷον κατασκευάσαι ἢ ἀνασκευάσαι· κατασκευάζοντι μὲν γὰρ ἀπόχρη δεῖξαι τινὶ ὑπάρχον, ἀνασκευάζοντι δὲ δεικτέον ὅτι οὐδενὶ ὑπάρχει.
VIII.
The Eighth Book of the Topica brings our attention back to the general considerations contained in the First. In the intervening part of the treatise we have had the quadruple distribution of dialectical problems, with the enumeration of those Loci of argument which bear upon each or all: we are now invited to study the application of these distinctions in practice, and with this view to look once more both at the persons and the purposes of dialectical debate. What is the order of procedure most suitable, first, for the questioner or assailant; next, for the respondent or defender?[363] This order of procedure marks the distinctive line of separation between the dialectician and the man of science or philosopher: to both of them the Loci of arguments are alike available, though each of them deals with those arguments in his own way, and in an arrangement suitable for his purpose.[364] The dialectician, being engaged in debate, must shape his questions, and regulate his march as questioner, according to the concessions obtained or likely to be obtained from his respondent; who, if a question be asked having an obvious refutative bearing on the thesis, will foresee the consequences of answering in the affirmative, and will refuse to grant what is asked. On the contrary, the philosopher, who pursues investigation with a view to his own satisfaction alone, is under no similar restriction. He looks out at once for such premisses as conduct straight to a conclusion; and, the more obvious their bearing on the conclusion is, the more scientific will the syllogism be, and the better will he be pleased.[365]
[363] Ibid. VIII. i. p. 155, b. 3: μετὰ δὲ ταῦτα περὶ τάξεως, καὶ πῶς δεῖ ἐρωτᾶν, λεκτέον.