In Proslogium St. Anselm presents his argument for the existence of God, an argument that has thus far withstood the test of time and many criticisms, one of which I will discuss here. Anselm works his way from the “fool’s” assumption that God does not exist, or at least does not exist in reality, through his premises that existence is greater than understanding alone and that a being with God’s properties and existence can be conceived of, to the conclusion that because God is that than which nothing greater can be conceived and God can exist in understanding, God must exist in reality. Gaunilo, a fellow monk, gives his criticism of Anselm’s argument in the form of a reductio ad absurdum argument. Gaunilo attempts to show Anselm’s argument to be false by taking a parody of Anselm’s argument to an extreme and absurd conclusion, that being the existence of the Perfect Island from the same reasoning as the existence of God. I then present a reply that I believe to be in accordance with something Anselm might have responded to Gaunilo with. This reply includes the explanation that the Perfect Island cannot be compared to God because the Perfect Island, if it were to exist, would be a finite and empirical Island and therefore imperfect by nature but God is infinite and therefore can and is perfect by nature. I will end with the conclusion that, based on St. Anselm’s argument, Gaunilo’s criticism and a possible reply to Gaunilo’s criticism, Anselm’s argument is true but only if