Disputation 5, Section 5:

• I. Statement of the position (n. 1)

• The view is that the existence of the individual is what gives it individual unity, though Suarez also discusses the more plausible view, which he attributes to Henry of Ghent and Dionysius Carthusiensis, that the subsistence of the individual, to be defined below, is the principle of individual unity.

• II. Arguments against existence as the principle of individuation (nn. 2-5)

• A. On the assumption that existence is not in reality distinct from essence:

• This is just a misleading statement of the nominalist position, according to which no principle of individuation is needed.

• B. On the assumption that existence is in reality distinct from essence:

• Note that Suarez does not accept this assumption, but nonetheless tries to show that even if it were true, existence could not be the principle of individuation.

• Suarez concedes (if you can call it that) that the position is true `formally', but not `materially'. The example helps explain what Suarez has in mind here. This white thing, as regards the formal notion of white, is constituted by whiteness. But the white thing itself, as a substance, is not constituted by whiteness. In the same way, each thing "has some individual notion under the concept of an existing thing" from its existence itself. This is to say simply that just as `Socrates is wise' is true by virtue of Socrates's wisdom, so too `Socrates exists' is true by virtue of Socrates's existence. However, assuming that Socrates's existence is distinct in reality from his essence, it is not the case that Socrates himself is constituted as this individual by his existence; it is rather his essence that so constitutes him. Indeed, his existence derives its own character, what we might call `Socrates-existence', precisely from the fact that it actuates his individual essence.

• Suarez goes on to give three arguments for this claim:

• The first is that even as merely possible beings (better: as ideas in the divine mind), Peter and Paul "essentially include their own individual notions." That is, God's idea of Peter, antecedent to Peter's existence, is an idea of this creatable individual, so that the proposition `Peter is by essence [or: necessarily] this human being' is every bit as true as `Peter is by essence [or: necessarily] a human being'. Hence, even if we assume that Peter and Paul are alike in every way that it is possible for them to be alike, it is still the case that God's willing to create Peter is (at least conceptually) distinct from God's willing to create Paul.

• The second argument is that if there is indeed a distinction in reality between essence and existence, then the essence qua potency is presupposed by the existence qua act. But `essence' in this context means not only the specific nature but the individuality of the entity involved. "Therefore, in the very sense in which the essence has per se the entitas of the essence, which is distinct from the existence and apt to be actualized by it, in that sense, too, it has its own unity and individuation."

• The third argument is that existence is itself a general notion, so that our familiar question arises with respect to it, viz., what makes this existence a this? No answer is satisfactory except for the answer that it is a this by its very self. But, Suarez asks, why not say the same thing about the essence?

• III. Arguments against subsistence as the principle of individuation (nn. 6-10)

• The subsistence of a substance is that by virtue of which it is a suppositum, or ultimate subject of predication. Because of the doctrines of the Trinity and the Incarnation, scholastic theologians hold that it is possible for a given individual nature not to have its own subsistence (Incarnation) or to have more than one subsistence (Trinity). So Suarez is willing to grant that a substance's subsistence is indeed distinct in reality from the substance itself. He conceives of subsistence as a mode of the substance, either a connatural mode (in ordinary cases) or a mode that comes to it from without (in the Incarnation). Now the position under discussion is that an individual's subsistence not only makes it an ultimate subject of predication but also consitutes it as an individual. It is this claim that Suarez disputes.

• Suarez's arguments for this claim, as well as his criticism of Henry of Ghent's construal of subsistence, would take us too deeply into the metaphysics of the Incarnation, a fascinating topic but one which we won't be taking up here. (For those who are interested, I've written a couple of papers on this topic.) Suffice it to say that if the orthodox understanding of the doctrine of the Incarnation is correct, then the view in question is automatically ruled out, since Christ's human nature is an individual even though it does not have its own subsistence.