The word ‘ontos’ means ‘being.’ The Ontological argument thus attempts to prove the existence of God a priori by focusing on the nature of his existence or being. St. Anslem (1033-1109) was the Archbishop of Canterbury. His argument was first presented in the form of a prayer in his book, ‘Proslogion,’ directed at the fool of the Psalm (Psalm 14) who says in his heart that there is no God.
There are two forms to Anslem’s Ontological argument:
1/ God can be defined as ‘that than which nothing greater can be conceived’
2/ We can all conceive of a perfect being in our minds, however we can also conceive of an even greater being that exists both in our minds (in intellectu) and in reality (in re)
3/ Beings that exist in both the mind (in intellectu) and reality (in re) are greater than those that only exist in the mind (in intellectu)
4/ Therefore God must exist both in the mind (in intellectu) and in reality (in re) otherwise something greater in reality (in re) could be perceived.
It is impossible to conceive of a God not existing (John Hick agreed):
1/ A necessary being is greater than a contingent being since a contingent being depends on something else for its existence and we can be thought of as not existing
2/ God can be defined as ‘that…