Medieval Philosophy

by Peter S. Adamson

place.6 Obviously, to meet the objection he has to show that it makes a difference that we are being asked to think about an island, as opposed to God. The difference is that existence belongs to the very nature of that than which nothing greater can be conceived, whereas existence cannot belong to the very nature of an island. As the American military proved when they were testing atom bombs in the Pacific Ocean, an island is the sort of thing that can go out of existence. So if we find ourselves entertaining the idea of an island that can’t possibly fail to exist, then we are entertaining something that makes no sense. By contrast, that than which nothing greater can be conceived is going to be something whose very nature guarantees its real existence. Anselm had already made this point in the Proslogion (§3).7 That than which nothing greater can be conceived is not merely something that exists, it is something that must exist. It exists necessarily, because it cannot even be conceived as not existing. I think this is a good response to the island objection. But the proof has been subject to many other criticisms. Apart from the island objection, the most well-known response is probably the one made by Kant, who argued that Anselm was wrong to take existence as a property on a par with features like justice, goodness, or eternity.8 Existence is not just one more property that I can think of a thing as having. This is why it struck an absurd note at the beginning of this ...