The role of ontological arguments in Christian theology is to prove that God exists. Saint Anselm developed his argument in the 11th century. Anselm’s argument was essentially a hypothesis. He broke down his argument into five key logics as follows. God is a being which is a greater being that can be imagined. The mind can imagine other beings. It is impossible for the mind to think of anything greater than God. If God did not exist it would be possible for the mind to imagine something greater than him. Because it is impossible for the mind to imagine anything greater than him then God exists (Rowe, 25). In simple terms, a being exists as an idea in the mind and, therefore, God exists as an idea in the mind. Because God exists only as an idea, one has the liberty to think of something greater than God. God exists because it is impossible to imagine something greater than him.
God exists as the supreme good and does not depend on any being. All other beings depend on him for their existence and for their well-being because of believe in divinity (Rowe, 28). He gave the illustration of a fool as stated in Psalms 14:1; 53; 1 that, “The fool has said in his heart, “there is no God’”. The fool believes in his understanding that there is no God, but cannot think of any being greater than God. There is nothing that can be thought of that is greater than God (Rowe, 29). God does not exist merely in understanding, but exists in reality as well. If that existed only in understanding, it would be possible to imagine something greater than it (Rowe, 30). Anselm’s argument was to prove the fact that God exists and possesses the virtues and ideals that Christians believe he has.
His work was criticized by Gaunnilo who wrote an argument titled “Reply on Behalf of The Fool”. Gaunillo contended that Anselm’s argument failed to give the fool any good reason to believe that it is impossible to think that something greater than God exists in reality. Gaunilo used the analogy of an island of which no greater island can be thought of (Rowe, 30). It is only possible to think of islands that we know in our understanding, but in reality there could be other islands that are greater than that one (Rowe, 35). Gaunillo concluded that Anselm’s argument was nothing but fallacy.
St. Thomas of Aquinas also rejected Anselm’s argument. To him it is obvious that God exists and God’s existence cannot be drawn from a series of deductions. People understand the word “God” to mean different things. Everybody does not understand God to be a being. Anselm’s argument can therefore only work for those who conceive God as a being and excludes the rest of the population (Rowe, 49). He also argued that a mental existence does not necessarily imply a physical existence. Immanuel Kant also opposed Saint Anselm’s theory. He argued that existence does not serve the role of validation. Thinking cannot prove the physical existence of something, because when thinking people are limited by their intellect and their actual experiences (Rowe, 50).
Saint Anselm was a great Christian philosopher and his proposal has had philosophers debating up to today. His argument is quite logical but it is not perfect and has flaws. People believe in different gods and to them their gods are beings who are greater than God. In some cultures, witchdoctors and voodoo are believed to be greater than God. They are those who believe in sacred animals and to them animals are beings which are greater than God. It is, therefore, delusional to base existence on the simple idea that no being greater than God can be thought of.