I’ve always felt that the ontological proof of the existence of God was one of the more compelling and interesting arguments about God. The proof, which was originally composed by Saint Anselm, amounts to a simple syllogism:
1) God is, by definition, the most perfect entity.
2) Something which exists is more perfect than something which does not exist.
3) Therefore, God exists.
It’s a natural first response to dismiss this argument as mere logical legerdemain, confusing words with their meanings. But I think that sort of thinking misses the real power of an omnipotent entity. For God, being omnipotent and encompassing the whole universe, thoughts are indistinguishable from actions. The universe as a whole is simply than the thoughts of God. If God thinks “what if Ian went to bed instead of writing in his blog” there would in effect be two different universes, albeit perhaps only temporarily. I don’t think we can casually dismiss the ontological argument without understanding that for God, words and meanings are the same thing. Or, to put it another way, the syntax is itself semantics.
I think the weak point in the argument is the notion that existence is more perfect than non-existence. I think existence implies change. If something truly never changes, then in what sense does it exist? The only way to not change is to not be subject to time. But how can we speak of something existing without speaking of some time in which it exists? (The observant reader will note that I am resorting to rhetorical questions, a sure sign of a shaky argument. These are definitional issues, but the definitions are the key to the ontological proof.)
The next step is to observe that if God changes, then it follows that God is not always the single perfect entity. If there are multiple possible perfect entities, then it follows that there are multiple Gods, which is not satisfactory. So there must be only one perfect entity. And it must never change.
So, since perfection implies not changing, and existence implies changing, it follows that non-existence is more perfect than existence. And thus we see that the ontological proof actually proves that God does not exist. At least not if we define God as the most perfect entity.
On a related topic, here is a brief consideration of the old schoolyard riddle: “Could God create a rock so heavy that He (or She) could not lift it?” As mentioned above, since God is omnipotent, any thought is reality. As Dante put it, “this has been willed where that which is willed must be.” So another way to put the question is “could God choose to never think a particular thought (namely, to lift that rock)?” Or, to put it yet another way, “could God lose the quality of being omnipotent?” I think the answer to that question has to be no: I don’t believe that an omnipotent being can cease being omnipotent. God might never, as a matter of fact, lift the rock. But it is not possible for God to be unable to lift the rock.