Anselm's Proof of God's Existence

Anselm of Cantebury wrote a proof of the existence of God in 1077 that has gotten much attention in the history of western philosophy, partly because of the importance of God in the history of western thought and partly because of the unique qualities of the proof itself. Proofs of God's existence are generally subdivided into various genre's and Anselm's proof is of the "Ontological Argument" type. "Ontology" is the study of Being; so ontological arguments are arguments that directly try to prove that God must exist as a fundamental feature of existence itself.

Anselm meant the argument to convince, but his audience certainly were not those who were unbelievers. The argument was addressed to sophisticated European Christians and for them it served to give reaffirm their belief, not convince. It's never struck me as convincing.

In brief the argument is: God is the greatest thing that one could possibly imagine. It would be even greater for God to exist in reality than in imagination and since God is the greatest thing that one could imagine, God must exist in reality, and not just in imagination. If God only existed in imagination then there could be something greater than God in reality.

I think I would describe the rhetorical force of this argument as its logical confusion. The logical knots that it employs can be intimidating and there is great rhetorical force to intimidation. In fact, explaining the essential fallacy in the argument can itself be quite confusing and may not be as compelling as the argument itself. This is part of the reason it's an enduring and compelling argument.

Let's first look at it very simply. The argument is basically saying that being able to imagine something that can't have anything greater, automatically means, by ontological necessity, that thing must exist. The rest of the argument is just misdirection to conceal this basic assertion.

This assertion gives a lot of power to the imagination. This is basically what Gaunilo of Marmoutiers was trying to show with his example of the island. He basically used the same basic form of the argument to prove that the greatest possible island must exist, on the same grounds that it would be greater for the island to exist in reality than in imagination.

The basic problem with Anselem's argument which we should notice is that there is a big leap from saying something would be greater if it existed in reality rather than imagination to something must exist in reality. If God only existed in imagination then certainly a God that existed in reality would be greater, but just because I can imagine such a God in existence, doesn't mean it automatically must exist in reality in order to satisfy the demands of my imagination. In short, my imagination could be wrong. If I can imagine the greatest thing that is, my imagination could be wrong and my imagination might be exceeding the limits of reality.

I don't know if my counter-argument is as convincing, or if it just muddies the water. Whatever the case may be, I want to treat more of Anselem's argument and it's descendants and I will return to it's appearances again in the history of philosophy, beginning with Descartes.