How does God exist?

If one hangs out near the classical theism water-cooler for long enough, one is likely to overhear, as I myself have overheard, that God is identical to his own pure act of existence. What exactly does that mean?

Existence & essence

The most basic thing that all beings have in common is that they all exist. This is true for God himself and for each and every being that he made. They all participate in various ways in the act of existence. While we might think of being as a static quality that beings have, for St Thomas, being is fundamentally understood as an act that a being does. To be, after all, is a verb.

The great variety of creatures indicates to us that, though the act of existence is common to all things, the ways in which a being can exist are innumerable. How does a tree exist?— or, in what way does a tree exist? A tree exists (it does its act of existing) according to its essence or nature: its tree-ness determines that it exists in a tree-like way, putting down roots, growing, photosynthesising—and all the exciting things that trees get up to. It does not exist in the same way as a man, a rabbit or a thundercloud do.

So all creatures have some essence (or, nature) that determines the manner in which they exist. The essence shouldn’t be understood as a Thing that is added to the act of existence, but rather, it is a sort of limiting principle on the act of existence. If you like, an essence is a pattern that determines the precise shape of the particular act of existence, something like how a choreographed dance specifies the act of dancing.

In creatures, we never come across the act of existence detached from a nature/essence. We always find existence and essence married together, though this analysis helps us to distinguish them.

Pure act of existence

In The One and the Many, W. Norris Clarke presents God as existing without essence or nature. The great I AM simply is his unlimited act of existence, existing in a way utterly undetermined by anything else.

And yet, Scripture speaks about “the divine essence” or “the divine nature” (for example, in 2 Peter 1:4: “ye might be partakers of the divine nature”). And, later in this very same book, Clarke himself describes God as having “a unique, unlimited essence”. How should we understand this?

Firstly, it seems clear enough that we should not understand the divine nature as some kind of limitation on God’s act of existence. Essences are limitations for creatures in their various acts of being, but not for God. Whatever else we might mean when we speak of the divine nature, we should be cognisant of God’s unrestricted act of existence.

Secondly, to return to my illustration of the dance, we shouldn’t think of God’s essence as some choreography that might have been different in another possible world. The essence of any given creature might have been different in another possible world, but we cannot say this of God. In fact, part of what it means for God truly to be God is that it is inconceivable that God could be different in other possible worlds. We can imagine possible worlds with an Earth bigger than our actual Earth, or in which the median height of men is smaller than it is in the actual world. But there is no possible world in which the eternal I AM is not omniscient or omnipotent, or in which the First Person of the Trinity is not the Father of the Second Person. God simply is, and he is who he is in every possible world.