What is St. Anselms ontological proof for the existence of God?
If one were to agree that existence in reality is greater than existence in the mind alone, then a being which none greater can be conceived in the mind must exist in reality, and this being would be God. http://en.wikipedia.org/wiki/Proslogion St. Anselm says that the crux of his argument — that the mind can’t possibly conceive of an existence greater than what exists in reality — is a given, so that is his proof.