20. Suppose that the definiend is one of the appetites, relative to an appetitum as correlate, a mode of the good or agreeable. You will take notice whether the definition given thereof enunciates the correlate as only an apparent mode of good: if it does not, you have a locus for attacking it. But if it does, and if the definer be one who believes in the Platonic Ideas, you may attack him by showing that his definition will not square with that doctrine. For the definition as so given will not suit for the ideal or generic appetite — the Self-appetite; which correlates with the ideal or generic good — the Self-good. In this no distinction is admissible of real and apparent: a Self-apparent-good is an absurdity.[308]
[308] Topic. VI. viii. p. 146, b. 36-p. 147, a. 11. ἐὰν δὲ καὶ ἀποδῷ τὸ εἰρημένον, ἐπὶ τὰ εἴδη ἀκτέον τὸν τιθέμενον ἰδέας εἶναι· οὐ γάρ ἐστιν ἰδέα φαινομένου οὐδενός, τὸ δ’ εἶδος πρὸς τὸ εἶδος δοκεῖ λέγεσθαι, οἷον αὐτὴ ἐπιθυμία αὐτοῦ ἡδέος καὶ αὐτὴ βούλησις αὐτοῦ ἀγαθοῦ. οὐκ ἔσται οὖν φαινομένου ἀγαθοῦ οὐδὲ φαινομένου ἡδέος· ἄτοπον γὰρ τὸ εἶναι αὐτὸ φαινόμενον ἀγαθὸν ἢ ἡδύ.
Compare Plato, Parmenides, pp. 133-134, where this doctrine that if the relatum be an Idea (sensu Platonico), the correlatum must also be an Idea, is enunciated and pushed to its consequences: ὅσαι τῶν ἰδεῶν πρὸς ἀλλήλας εἰσὶν αἵ εἰσιν, αὐταὶ πρὸς αὑτὰς τὴν οὐσίαν ἔχουσιν, ἀλλ’ οὐ πρὸς τὰ παρ’ ἡμῖν εἴτε ὁμοιώματα εἴτε ὅπῃ δή τις αὐτὰ τίθεται, &c. — αὐτὴ δὲ δεσποτεία αὐτῆς δουλείας ἐστὶν ὅ ἐστι, &c. (133, C-E.)
21. Again, suppose that the definiend is a habit or disposition. You will examine how far the definition fits as applied to the individual person who has the habit; and how far it fits when taken in comparison with subjects contrary or congeneric. Every such definition, if good, implies in a certain way the definition of the contrary: he who defines cognition furnishes by implication the definition of ignorance.[309]
[309] Topic. VI. ix. p. 147, a. 12-22.
22. Or suppose the definiend to be a generic relatum, and the definition to enunciate its generic correlate. You must call to mind the specific terms comprehended under these two generic terms, and observe whether they fit on to each other respectively. If they do not, the definition is faulty.[310]
[310] Ibid. a. 23-28.
23. You will farther examine whether the Opposite of the definition will serve as definition to the Opposite of the definiend, as the definition of half is opposite to the definition of double; thus, if double is that which exceeds equality, half is that which is exceeded by equality. The like is true of Contraries: if the profitable be that which is productive of good, the hurtful will be that which is productive of evil or destructive of good. If, on trying the contraries, you find that this will not hold, the definition originally given will be found unsatisfactory.[311] In defining the privative contrary of any term, a man cannot avoid enunciating in the definition the term of which it is the privative: but he is not allowed to define the term itself by means of its privative. To define equality — that which is contrary to inequality, is improper. You will require him at once to define inequality; and his definition must be — the privation of equality. Substitute this definition of the term inequality, in place of that term itself, in the above-named definition of equality: and the last definition will then run as follows: Equality is that which is contrary to the privation of equality. Here the definiend is enunciated as a part of the definition of itself; a proof that the original definition — Equality is the contrary of inequality — is itself wrong.[312]
[311] Topic. VI. ix. p. 147, a. 29-b. 4.
We most remember that Aristotle, classifying Relata as one species under the genus Opposita, treats double and half as Opposita, i.e. Relative-Opposita. I have already said that I think this classification improper, and that Opposita ought to be ranked as a species under the genus Relata.