In this reading we encounter St. Anselm's ontological argument for the existence of God and Gaunilo's reply. The argument goes like this: God is by definition "a being than which nothing greater can be conceived." If God, the greatest being that can be conceived, exists only in our minds, then there must be a being greater than God-that is, a God that exists in reality (an existing being is greater than an imaginary one). But this leads to a contradiction: A being greater than God is impossible. Therefore, God must exist in reality (as well as in the mind). Gaunilo replies that if Anselm's reasoning were sound, we could prove something ridiculous-namely, that the greatest island possible exists in reality.
-Arguments like Anselm's rest on logic alone.

Question

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Anselm's ontological argument indeed posits that God, being the greatest conceivable being, must exist in reality because a being that exists is greater than one that does not. Gaunilo's reply challenges this logic by applying it to a perfect island, suggesting that if Anselm's argument were valid, it could be used to prove the existence of any perfect concept, which is absurd.

In This Reading We Encounter St