Find yourself a comfortable chair.St. Thomas, you recall, said that God is being itself. This would be greater than Zeus; it would even be greater than the author, relative to her story (the author, after all, eventually dies). But can it be true? Is there any way of demonstrating “being itself”?Now, I am not Thomas; I am hardly a Thomist. What follows is elementary and therefore incomplete. Still, taste and see, and maybe you will also wish to pursue the genius of St. Thomas at length.
Act and Potency
St. Thomas followed in the tradition of Aristotle, who believed that all knowledge began with the senses. From observation, one could apprehend universals, which tell us the ideal pattern which forms each kind of thing in reality. Following the rules of logic, one could contemplate the world and come to conclusions about the nature of things. (Does this sound similar to the scientific enterprise? It is not a coincidence).One of Aristotle’s observations was that all things are combinations of act and potency, and St. Thomas agreed. First, what does this mean?By act, we mean what a thing is “right now.” Take the example of a rock – pick one up if you can. The rock I’m looking at is grayish, lightly speckled, a bit like an oblong golf ball. Let’s say it weighs 4 oz.Those properties I’ve listed – grayish, oblong, 4 oz in weight – are properties that this rock has actualized. You can think of act as what a thing actually is, right in front of you.By potency, we mean the way a thing could potentially be. My rock, for example, could be painted blue. It could be sharpened, or smashed to bits. These are potencies of the rock. It is within the nature of a rock to take on these various properties, but the rock does not manifest them at this moment. (If they are potential, then they are not actual right now).Now, Thomas said all things are combinations of act and potency. We have seen this in the rock – actually gray, potentially blue – and no matter how many potencies are actualized, there remain some other potencies which cannot be actualized at the same time. The rock cannot be completely gray and completely blue at the same time (nevermind completely green, yellow, mauve…).
Reducing potency to act
The transition from potency to act is called a reduction – i.e. The potency of a thing is reduced to act. The actually gray rock may be reduced to a blue rock. One supposes it may be reduced again, back to being a gray rock.If my approach is accommodating, our thoughts will be of one accord. To this point, we have simply taken an everyday object – a rock – and tried to grasp the underlying reality behind it. Behold, metaphysics at work.This differs from science, in the sense that science would continue to explore the accidents of the rock – what minerals is it composed of? How old is it? If it has any practical uses, what uses are those?But God is not an object of scientific inquiry. He has no mass, no color or odor. He is utterly beyond all of that, just as an author is beyond the “physics” of her story. If we are to consider such a claim, then we must study whatever is “behind” physics, whatever is outside the scope of science, but nevertheless real.What governs the reality of a rock? In short, the interplay of potency and act governs the reality of a rock. (Notice, we are not assuming either the existence or the non-existence of God – we are not “begging the question” either way).This is important because Thomas now gives us a rule, a law of metaphysics: Nothing can reduce its own potency to act. In other words, something independent of an object must act on it, thereby reducing the potentiality to an actuality.In order for the gray rock to be reduced to a blue one, a mover is needed. The gray rock does not paint itself blue. A paintbrush could, and it acts on the rock and causes the transition from potency (potential to be a blue rock) to act (actually a blue rock).This is no arbitrary rule, of course, but one borne out by reality, like a law of nature, like gravity. Another example: A newspaper is potentially hot, but it does not set itself on fire. In order for this potency (potential to be hot) to be actualized (actually hot), we must light a match, or something similar.