About this question, which Aristotle explicitly discusses,104 there occurs nothing new besides those things which have been noted in Chapter 1, Question 7. But some questions do occur about what Aristotle has inci-dentally mentioned, especially with respect to Text 10.
Question 1. Whether a genus is directly (per se) predicated of the differ-ences by which it is contracted? Or as it is usually asked in another way:
is it essential to a genus that it have differences outside its concept (ratio), that is, [differences] in whose intrinsic and essential concept the genus itself is not included? For the Philosopher evidently supposes this in the argument which he fashions in Text 10.105 And lest someone say that he
is not proceeding in this text in a definitive way (definiendo) but only for the sake of argument (argumentando), the same Philosopher proves this [point in question] explicitly in the Topics, Book 6, Chapter 3.106 Therefore, this question is in one sense metaphysical and in another dialectical. For it is metaphysical insofar as it highlights the question between genus and difference and the precision of one from the other as well as the mode of composition of a species from these [i.e. genus and difference], and in this sense it is indicated by the last words cited above, and it is sufficiently treated by us in Disputation 6, Sections 5107 and 6.108 And what is treated in Disputation 2, Section 6,109 and Disputation 39, Section 2,110 comes to the same thing.
However, this question is dialectical insofar as it asks about the quality of a predication, namely, whether the predication of a genus with respect to its differences, or vice versa, is essential, for example [the predications]
“rational is animal111” (rationale est animal), or, “animal is rational112” (ani-mal est rationale). And in this sense, [John of ] Jandun treats the question extensively in Question 12113 and he affirms that it is essential. Antonio Andreas, in Question 2,114 and [Chrysostomos] Javellus, in Question 2,115 also treat it and they deny that it is essential. Again [Agostino] Nifo treats it in his Disputation 2116 and uses various distinctions.
But the matter is both extrinsic [to the present discipline] and also clear.
For those propositions are not in the first or second mode of essential predication which Aristotle distinguished in the Posterior Analytics, Book 1117—because in them the predicate is not of the essence of the subject nor is the subject essential to the predicate. And the reason is taken a priori from the explanation of the first [i.e. metaphysical] sense. For since genus and difference are so related /p. XIII/ that one is outside the concept and the essential nature of the other, and a difference is not otherwise a prop-erty flowing from the nature of the genus, as is self–evident, it results that one cannot be predicated of the other either in the first or second mode of essential predication.
But if someone wishes [to explain it] in another way according to other essential (per se) modes posited by Aristotle in Metaphysics Book 5, Chap-ter 18,118 or by still other modes which can be fashioned, as for example, when “essential” (per se) is distinguished against “through something else”
(per aliud), or as it excludes an accidental (per accidens) composition—for instance, when a difference is joined essentially (sicut per se) to a genus, that is, immediately and not through something else (per aliud), or when a genus and a difference essentially (per se) and not accidentally (per accidens) compose one thing—in these ways it can be said that one is predicated
Metaphysics Book III 61 essentially (per se) of the other. But these ways of essential predication are not as usual (usitati) as the first ways—besides the fact that these predica-tions are in a certain respect not natural but in some manner improper and in this also they fall short of essential propositions. For even though a divisive difference is related to a genus in the manner of a form, still it is less universal than the genus. But, on the other hand, even though the genus is more universal, it is however related to a difference as potency and not as act, and therefore it is not so properly and directly predicated.
Absolutely, therefore, these propositions should be excluded from the number of essential (per se) propositions.
Question 2. Whether to have differences outside its own concept, in which differences it is not included nor of which it is essentially predicated, is not only natural to a proper genus but also natural to every univocal predicate, or to every predicate having one objective concept119 common to all things contained under it? We have addressed this question in Disputa-tion 2, SecDisputa-tions 5120 and 6,121 where we have shown that it is not necessary that such a property belong to every predicate which is common according to the same objective concept. And in Disputation 39, Section 2 [sic],122 we have shown that it does not belong to every essential or quidditative predicate. Moreover, Aristotle in this place has spoken only about a proper genus—whatever some commentators contend. And we have addressed the same matter in Disputations 32123 and 30.124
Question 3. Whether a species is essentially predicated of a difference which is constitutive of it, as for example, [in this proposition] “rational is man”125 (rationale est homo)? The authors cited above treat this question in this place—and some answer in the affirmative, others in the negative, and still others use distinctions. But we have put it aside: first, because it is a question for logic, and, second, because (as Fonseca well indicated in his commentaries126) Aristotle thought that the negative position was so evident that he left it without proof and explanation.127
Nor is there any problem resulting from what others object, namely, that in that proposition the subject is of the essence of the predicate and it is therefore in the second mode of essential predication, for this is the definition of that second mode. Likewise, because this proposition, “Man is rational” (homo est rationalis) is in the first mode of essential predication, therefore, the proposition which converts with it will also be essential at least in the second mode.
These (I say) and similar things are not a problem. For that proposition [“rational is man”] is not natural, but indirect, most improper and apart from nature;128 and, therefore, it is outside the whole range of essential
propositions. For those definitions of essential modes must be understood with regard to predicates and subjects which are proper and connatural—not about those which are composed and converted by us in an inverse and contranatural order. Hence, it also can be said that the genus when proposed in those definitions constitutes a proper and natural proposition. And for the same reason it is not necessary that one essential proposition be con-verted into another, when by that conversion there is effected an indirect and improper proposition. Add also that this proposition is essential in the first mode: “Man is animal” (Homo est animal), but this proposition,
“Animal is man” (Animal est homo) is essential in no mode.
I see this controversy to be about the way of speaking; and I see that many think that this proposition, “Risible is man” (Risibile est homo), is in the first mode of essential predication even though it is indirect. But, nevertheless, the first mode is more formal and more proper. Otherwise, this proposition also, “Rational is man” (Rationale est homo) would be in the first mode of essential predication. For if “man” is put in the definition of “risible” why not in the definition of “rational”? In this way the same proposition, “Rational is man” (Rationale est homo), would be in both the first and the second mode [of essential predication]: which is absurd.
Therefore, these indirect propositions are outside the order of essential propositions. On this, see Cajetan [commenting on] the Posterior Analytics, Book 1, Chapters 4129 and 18.130