Wednesday, August 29, 2012

The Definitive Proof of God's Existence

I refer to the following argument as a "metaphysical argument," because it has a close resemblance to both cosmological and ontological arguments.  I think it deserves its own category.  The argument I'm referring to is the proof found in St. Thomas Aquinas's small tract, De Ente et Essentia (On Being and Essence).

Now, I've written quite a bit about the distinction between being and essence in past entries, but I'd like to provide a brief overview of the argument.

Essence: what a thing is, e.g. its nature.
Being: that a thing is, e.g. its existence or actuality.

We know that the essence of a unicorn (roughly) is of a magical horse with a horn.  However, that doesn't commit us to saying that a unicorn exists.  The difference between a real unicorn and a not-real unicorn is that the former exemplifies being, even though the essence of each is relatively the same.

While there are many essences, there is only one being.  For, to be distinct from being is to be non-being.  Since anything with non-being simply doesn't exist, it follows that we are justified in deducing the unicity of being.

1. Something exists. (Premise)

2. Necessarily, something can exist if and only if being exists. (Definition)

3. Therefore, being exists. (From 1 and 2)

(2) is true by definition.  If there is no being (existence), then nothing can possibly have the attribute of existence.  I strongly disagree with Kant on this matter.  If being/existence is not a thing, then a real unicorn and a non-real unicorn differ by a non-thing (literally, nothing), which is the same as saying that they are not distinct at all.  Since this is absurd, it follows that being exists.

Since we have already established the unicity of being, what are some of the other divine attributes we can deduce?

Being must be eternal and omnipresent.  After all, there is no time or place at which anything can exist apart from being.  On the same token, being must be temporally necessary, by virtue of its necessary eternality.

Being must also be omnipotent.  Since being is the efficient first cause of all essences, and because no effect is greater than its cause, it follows that being is capable of actualizing all potentialities that essences are able to actualize.

In sum, being exists, and being possesses the divine attributes of unicity, eternality, omnipresence, temporal necessity and omnipotence.  This, as the Angelic Doctor muses, everyone understands to be God.


  1. Isn't this proof, as it's stated, as much a proof for pantheism as it is for theism? It seems God/Being is a part of all of us.

  2. Hi Jay,

    It could be construed as an argument for pantheism or for theism. Theists don't deny the imminence of God, only that he is distinct from creation. One way of maintaining that God and creation are distinct is to point out that only God is being itself subsisting; whereas other entities, while participating in the same being, possess essences distinct from their being.

    By Leibniz's Law:

    God: being and essence are identical
    Creation: being and essence are distinct

    Therefore, God and creation are distinct.

    Make sense?

  3. I understand the distinction between God and creation that you make and agree with it. However, I don't think the proof above gets us there (admittedly some of Aquinas' other proofs do). I was curious whether the proof could be improved to favor theism over pantheism.

  4. I see what you mean. One possible way of doing that is to show that God can exist without creation. The kalam and contingency arguments, for example, can be used to supplement the metaphysical argument. I don't think the latter can do that on its own, but I'd love to be proven wrong.

  5. On the other hand, if a thing's being and essence are distinct, it seems that that thing is contingent.