In Anselm’s book Proslogion (Discourse on the existence of God,) Anselm defined God as ‘that than which nothing greater can be thought’ and from this Anselm developed the first part of his argument. It means that a being that cannot be improved upon and to think of a greater being must be God. Anselm supports the statement in Psalms that ‘The fool has said in his heart “there is no God”.’ Anselm says that it is absurd that an atheist (fool) can understand the definition of God that no greater can be conceived but at the same time rejects it and denies the idea of God existing. Anselm seeks to prove the fool wrong by saying that God does not exist, as someone who can understand the definition of God must have the knowledge of a God. Anselm makes a distinction between an object ‘in one’s’ understanding and ‘to understand’ that the object exists. This means that there is a difference between saying that something exists in understanding and that someone believes in it, for example, unicorns exist in people’s understanding but people know that they do not actually exist. Anselm argued that according to the definition of God, if God exists in the mind (in intellectu) then a greater being must exist in both the mind and in reality (in re.) As God is something that which nothing greater can be conceived and the greater though is God means that in conclusion God must exist.
Anselm uses his power of reason to prove that God exists- reduction ad absurdum. Suppose God only exists in one’s understanding, God could then be greater by existing in reality, meaning a greater God is possible and exists in reality. However, if God is the greatest thing which can be though of then God must exist in the mind and in understanding. Anselm has faith in the existence of God and through logic has demonstrated that the opposite opinion that God does not exist would be absurd.
Anselm’s second part of the his argument is a development of his first part and he attempts to prove God’s existence further by saying His existence is necessary. Anselm is referring to the eternal nature of God and that because God exists so truly he cannot be thought of as non-existent. If God is necessary then there is no possibility of him not existing. Anselm says that we know that God’s existence is necessary because nothing greater than God can be thought, to be thought not to exist would be inferior to thinking of something that must always exist and therefore God has necessary existence.
Anselm explains the difference between the believer and the fool (atheist,) he says that the fool knows the word God but does not know God himself. Whereas, the believer can understand that because God is the greatest being ever to be though of then this means he must exist. Anselm believes that humans are contingent beings, which means we might never have been and can be added to or change. We may not have ever existed and we can also die whereas God is perfect by definition and cannot be changed. He is a necessary being and has a cause.
