Friday, May 21, 2010

TGD: Chapter Three - Cosmology and Omnipotence

In Chapter Three of "The God Delusion" Dawkins begins to address the arguments for God's existence. The first section concerns Aquinas' five proofs for God's existence.

Not surprisingly, Dawkins isn't impressed with Aquinas' arguments. I can understand why. Dawkins and Aquinas are working from different assumptions. They both understand the universe in radically different ways. Dawkins is a student of modern science, biology in particular, and Aquinas was a student of Aristotelian metaphysics.

So it will be my task to try and bridge the gulf that separates these two great minds and see if we can find some common ground. Let's get started.

Aquinas' first three proofs are the argument of the unmoved mover, the argument of the first cause, and the argument from contingency. Dawkins groups these arguments together, since they have a similar form. I will focus on the argument from contingency, sometimes called the cosmological argument, because it is the strongest.

This is Dawkins' summary of the argument: "There must have been a time when no physical things existed. But, since physical things exist now, there must have been something non-physical to bring them into existence, and that something we call God."

It's worth pointing out that modern science actually strengthens this argument. According to the Big Bang Theory, the universe has a definite beginning in time. This suggests that the universe isn't self sustaining, but was brought into existence by some outside force.

Moreover, even if the Big Bang Theory turned out to be incorrect (even though there is some very solid evidence for the theory), it is impossible for the universe to be infinitely old. If it were, then according to the second law of thermodynamics the universe would have reached a state of maximum entropy by now, which would make it impossible for life to exist.

So the cosmological argument effectively proves that the natural universe was created by an external force, which Aquinas calls God. Unfortunately, this is as far as the cosmological argument takes us. Dawkins rightly points out that, based on these arguments alone, there is no reason to assume that this "God" is a being with all the attributes we normally associate with God.

At this point, Dawkins has a brief digression where he talks about God's attributes. He claims God's omniscience contradicts his omnipotence since, if God already knows what he is going to do in the future he cannot change his mind. This is a silly argument, similar to asking if God, being omnipotent, can make a boulder so heavy he can't lift it. Both assume that there is a contradiction in the will of God.

In the example of God making a boulder so heavy he can't lift it, the contradiction is obvious. God wants the boulder to stay on the ground while at the same time wanting to lift the boulder. The argument assumes a contradiction to prove a contradiction. I'm not impressed by it.

The argument about God changing his mind is more subtle, but is basically the same. God wants to do something in the future, but when the time comes he wants to do something else. However, if God is omniscient, his knowledge doesn't change over time. So God has no reason to change his mind, if we assume that God's will is consistent. We only get a contradiction if we assume that God's will is contradictory.

What this really boils down to is, can God do something that is logically impossible? As many theologians have pointed out, not being able to do things that are logically impossible isn't really a limit on omnipotence. Contradictions are, by definition, nonsense. Saying that God cannot perform nonsensical actions doesn't place any meaningful constraints on God's power.

I'm afraid this post is getting long, so I'll stop here for now. Next week I'll write about the rest of Aquinas' proofs as well as the ontological argument for God's existence.


  1. There's another option on the cosmological argument, which is that the universe (space+time) is finite, but without boundary. Sort of like the surface of a sphere. Hawking proposed an idea like this in "A Brief History of Time".

    In a model like this, time doesn't exist apart from the universe, so questions about the origin of the universe don't make sense.

    Of course, you can still ask why the universe exists.

  2. I will have to read Hawking at some point. I'm curious about how he addresses the problem of entropy though. If time is closed, like a loop, then at some point the total entropy in the universe would need to decrease. Is this explained by a "big-crunch"?

    I should note that I used Dawkins' rephrasing of the argument, for the sake of convinience. Aquinas' original argument doesn't depend on the universe having a definite beginning in time. Instead it depends on the universe needing an explanation for its existence.

    The cosmological argument will come up again, so I'll have a chance to revisit it. I will probably explain the argument a little more thoroughly when that happens.