Arguments for God’s Existence: Anselm and Aquinas

Imagine a God0 that had every attribute that a God1 has (omnipotence, omniscience, omnibenevolence, etc.) except existence. By premise two, having existence is better than not having it. So only God1, not God0, could be God according to Anselm’s definition. Several philosophers, including Descartes (1596–1650), followed Anselm in putting forth a variation of the argument. A contemporary of Anselm’s named Gaunilo was an early opponent, who thought the argument would allow us to prove the existence of a perfect island, a perfect valley, etc. David Hume criticized the argument on different grounds: only experience counts as evidence concerning a question of fact or existence. Concepts in themselves articulate possibilities only. Experience tells us whether a concept is exemplified in the world. In other words, experience tells us what exists. Immanuel Kant (1724–1804) advanced another critique, insisting that “existence is not a predicate.” Existence is not an attribute like any other. The proposition, “All triangles have three sides,” can be true even if there are no triangles, and we can know it is true. But only experience can tell us that there are indeed triangles in the universe. Similarly, we know that a unicorn would have a single horn whether or not there are in fact any unicorns. But no concept can tell us whether unicorns exist. Not all philosophers, however, find these criticisms conclusive against all versions of the ontological argument. Anselm puts forth a second argument, also ontological and a priori, that concerns necessary existence rather than existence. This second argument implies