[257] Topic. VI. i. p. 139, a. 24-35: τῆς δὲ περὶ τοὺς ὅρους πραγματείας μέρη πέντε ἐστίν.
As to the first of these five heads, the Loci bearing thereupon have already been enumerated in the Third Book, on Accident: in accidental predications the question raised is always about the truth or falsehood of the predication.[258] As to the second and third of the five heads, these have been dealt with in the Fourth and Fifth Books, enumerating the Loci on Genus and Proprium.[259]
[258] Topic. VI. i. p. 139, a. 36.
[259] Ibid. b. 3.
There remain the fourth and fifth heads, on which we are about to enter: (1) Whether the definition is well expressed or set out (the fifth head); (2) Whether it has any right to be called a definition at all, i.e., whether it declares the Essence of the subject (the fourth).[260] The fifth is taken first, because to do a thing well is always more difficult than to do it simply, and is therefore likely to afford greater opening for argumentative attack.
[260] Ibid. b. 6.
The definition, while unobjectionable in substance, may be badly set out in two ways. First, it may be indistinct in terms — not plain nor clear. Next, it may be redundant: the terms may include more than is required for the definition. Under each of these defects of expression several loci may be indicated.[261]
[261] Ibid. b. 12-18.
1. Indistinctness may arise from the employment of equivocal terms in the definition. Or it may arise from the term to be defined being itself equivocal; while the definer, taking no notice of such equivocation, has tried to comprehend all its senses under one and the same definition. You may attack him either by denying that the definition as given covers all the different meanings of the definiend; or you may yourself distinguish (which the definer has omitted to do) these different meanings, and show that none of them or few of them are covered by the definition.[262]
[262] Topic. VI. ii. p. 139, b. 19. ὁμοίως δὲ καὶ εἰ τοῦ ὁριζομένου πλεοναχῶς λεγομένου μὴ διελὼν εἶπεν· ἄδηλον γὰρ ὁποτέρου τὸν ὅρον ἀποδέδωκεν, ἐνδέχεταί τε συκοφαντεῖν ὡς οὐκ ἐφαρμόττοντος τοῦ λόγου ἐπὶ πάντα ὧν τὸν ὁρισμὸν ἀποδέδωκεν.