[243] Topica, V. vii. p. 136, b. 15-32.
18. Analogous cases or propositions:— If the respondent affirms A as proprium of B, you have an argument against him by showing that something analogous to A is not proprium of a subject analogous to B. Thus, the builder, in relation to house-making, is analogous to the physician, in relation to health-making; now health-making is not the proprium of the physician, and therefore neither is house-making the proprium of the builder. If the respondent has advanced a negative, you will apply this same locus in the affirmative against him: e.g., as it is the proprium of the gymnast to impart a good habit of body, so it is the proprium of the physician to impart health.[244]
[244] Ibid. b. 33-p. 137, a. 7.
19. Esse, and Generari or Fieri:— If A considered as Ens is not the proprium of B considered as Ens, then neither will A considered as Fiens be the proprium of B considered as Fiens. Vice versâ, on the affirmative side: if the former of these two be the fact, you may argue that the latter is the fact also.[245]
[245] Topic. V. vii. p. 137, a. 21-b. 2.
20. Comparison with the Idea:— If the respondent sets up A as proprium of B, you will turn your mind to the Idea of B, and note whether A is proprium of this Idea, in the same sense and under the same aspect as it is affirmed to be proprium of B. If it be not so, you will have an argument in refutation of the respondent. Thus, if he maintains that it is a proprium of man to be at rest, you will argue that this cannot be so, because to be at rest is not the proprium of the Self-man (αὐτοάνθρωπος) quatenus man, but quatenus Idea. Vice versâ, you will have an affirmative argument, if you can show that it is the proprium of the Idea. Thus, since it is a proprium of the self-animal quatenus animal to be composed of soul and body, you may infer that to be composed of soul and body is really a proprium of animal.[246]
[246] Ibid. b. 3-13.
21. Locus from More and Less:— Suppose the respondent to affirm A as proprium of B: you will have an argument against him, if you can show that what is more A is not proprium of that which is more B. Thus, if to be more coloured is not proprium of that which is more body, neither is to be less coloured proprium of that which is less body; nor is to be coloured proprium of body simply. Vice versâ, if you can show that what is more A is proprium of what is more B, you will have an affirmative argument to establish that A is proprium of B. Thus, to perceive more is proprium of that which is more living. Hence, to perceive simply is proprium of that which is living simply; also, to perceive most, least, or less, is proprium of that which is most, least, or less living, respectively.[247]
[247] Ibid. viii. p. 137, b. 14-27.
If you can show that A simply is not proprium of B simply, you have an argument to establish that what is more or less A is not proprium of that which is more or less B. If, on the other land, you show the affirmative of the first, this will be an argument sustaining the affirmative of the last.[248] Perhaps you can show that what is more A is not proprium of what is more B: this will be an argument to show that A is not proprium of B. Thus, to perceive is more proprium of animal than to know is proprium of man; but to perceive is not proprium of animal; therefore, to know is not proprium of man. Or again, if you can show that what is less A is proprium of what is less B, this will form an argument to show that A is proprium of B. Thus, natural mansuetude is less proprium of man than life is proprium of animal; but natural mansuetude is proprium of man: therefore life is proprium of animal.[249] Farther, if you can show that A is more a proprium of C than it is a proprium of B, yet nevertheless that it is not a proprium of C you may thence argue that A is not a proprium of B. Thus, to be coloured is more a proprium of superficies than it is a proprium of body; yet it is not a proprium of superficies; therefore, it is not a proprium of body. This last variety of the locus of More and Less (Aristotle remarks) affords no corresponding affirmative plea;[250] for the same predicate cannot be a proprium of many subjects. If A be really a proprium of superficies, it cannot be also proprium of body. Lastly, you may perhaps be able to show that C is more a proprium of B than A is a proprium of B; yet, if C is not a proprium of B, you will infer negatively that neither is A proprium of B. Thus, to be perceivable is more proprium of animal, than to be divisible is proprium of animal; yet to be perceivable is not proprium of animal, and, therefore, neither is to be divisible proprium of animal. You may invert this argument for the affirmative, if you can show that C is less a proprium of B than A is a proprium of B, yet still that C is a proprium of B; hence you will infer, Ã fortiori, that A is a proprium thereof. E.g., If to perceive is less a proprium of animal than to live is a proprium thereof, yet to perceive is a proprium of animal; then, to live is so likewise.[251]