We’re blogging through St. Thomas Aquinas’ Compendium Theologiae, sometimes called his Shorter Summa. Find the previous posts here.
It’s been a month since the last entry in the series, so it’s time to recap. Thomas began by showing that there is a first, ultimate cause of all caused things; he calls this ultimate cause “God” for convenience, though he’s still in the process of showing why it’s reasonable to equate this first cause with the God of Abraham, Isaac, and Jacob. He’s determined a number of particular things about this God; and for the last couple of chapters he’s been showing that this God is metaphysically peculiar—none of the usual metaphysical categories (as defined by Aristotle and others) are appropriate for God. Among these categories are the terms “genus” and “species”, which mean something rather different than the modern biological sense; if you’re unclear on that, you might want to review the last couple of posts.
Thomas continues his project of showing that none of the usual metaphysical categories apply to God by showing that God is a not a species. Not that it’s likely that He would be; Thomas is just being thorough.
God cannot be, as it were, a single species predicated of many individuals.
To predicate X about something about something is simply to say that X is true about something. If I say that Spot is brown, I’m predicating brownness of Spot. If I say that Spot is a dog, I’m saying that Spot belongs to the species “dog”; and since there are many dogs, “dog” is a species predicated of many individuals. But God is not this kind of thing.
Various individuals that come together in one essence of a species are distinguished by certain notes that lie outside the essence of the species.
For example, men are alike in their common humanity but differ from one another in virtue of something that is outside the concept of humanity.
People are the same way. They have the essence of humanity, plus their own individual characteristics.
This cannot occur in God, for God Himself is His essence, as has been shown. Therefore God cannot be a species that is predicated of several individuals.
We’ve already established that God is His essence and nothing more; so He can’t include individuals with accidental characteristics.
As usual, Thomas gives a second proof:
Again, a number of individuals comprised under one species differ in their existence, and yet are alike in their one essence. Accordingly, whenever a number of individuals are under one species, their existence must be different from the essence of the species.
You and I share in the essence of humanity; Spot and other dogs share in the essence of dogginess. It’s possible to contemplate dogginess apart from any particular dog (as we’ve been doing; Spot exists only in our minds), but to get a real dog you need to add existence to the essence of dogginess.
But in God existence and essence are identical, as has been demonstrated. Therefore God cannot be a sort of species predicated of many individuals.
But God is all in all; He is His essence, and His essence is His existence, and if you had to add anything to Him He wouldn’t be God.