Medieval Philosophy

by Peter S. Adamson

of something, I am conceiving of it as having a range of properties. Its existence is simply the realization or instantiation in the world of something that has those properties. Whether this same objection can so plausibly be applied to the idea of necessary existence, though, seems to me to be an open question. Even if existence is not a (great-making) property like justice or eternity, the trait of existing necessarily might be. But I think we don’t need to deny that existence, or necessary existence, is a property in order to defeat Anselm’s argument. If the way I’ve set it out does capture Anselm’s line of reasoning accurately, then it has a more fundamental flaw. For me to say that necessary existence is included in the very nature of a thing is not yet to assert that the thing exists. Rather, it is to say that if the thing did exist, then it would by its very nature exist necessarily. This seems not only right, but a genuine insight on Anselm’s part, and one strikingly parallel to what Avicenna had been doing just a few years previously. Anselm realized that if God is to be that than which nothing greater can be conceived, He would be the sort of thing that cannot fail to exist. But this, as far as I can see, just means that God cannot exist contingently. In other words, He can’t exist while possibly not existing. From this it doesn’t follow that God in fact exists. Gaunilo made this same point in a passage which should be remembered alongside his much more frequent...