Explain Rene Descartes Developments to the ontological Argument

Explain Rene Descartes developments to the ontological argument

The ontological argument is the only a priori argument for the existence of God; and was first presented by Anselm of Canterbury in his work, the Proslogion. It is made usuing analytic statements, and is therefore considered a deductive argument. It is to be noted however, that not only was Anselm not trying to argue directly for God's existence (the argument proper is in fact a prayer and address to God), but that it was Immanuel Kant who first named Anselm's argument the 'ontological' (literally, 'of being). The argument, due to extensive criticisms during the 13th century by Thomas Aquinas, fell somewhat out of fashion for almost 400 years. However, philosophers such as the French Enlightenment thinker Rene Descartes rejuvenated interest and debate in the argument, when he elaborated upon Anselm's earlier work, in his 5th Meditation.

Anselm's argument can be split into two distinct forms, found in Chapters II and III of his Proslogion respectively. Both begin with the claim that God is 'that than which nothing greater can be conceived.' The first form has clear links to Platonic philosophy, and is based on the fact that 'The fool says in his heart there is no God' (Psalm 14). Anselm says that even the fool can have an idea of God in his mind, or in intellectu, despite denying that God exists. He then establishes that something that exists both in reality, in re, as well as in intellectu, is greater than something which exists only in intellectu. Anselm then argues that because God is the greatest conceivable being, God must exist both in re and in intellectu, because otherwise there could be conceived a being who is greater than God- which contradicts Anselm's earlier statement.

The second form of Anselm's argument, and that which provoked greater development from Descartes, concerns the nature of both contingent and necessary existence with regards to God. He also states that a being whom cannot be conceived not to exist, a necessary being, is greater than a being whom can be conceived not to exist, a contingent being. In this way, for God to remain 'that than which nothing greater can be conceived', God must exist necessarily. In his 1993 Metaphysic, Van Inwagen summarised this by saying that 'any assertion of the non- existence of God must be self contradictory.'

It is to be noted that in both arguments, Anselm argues from God existing de dicto, to God existing de de: God is argued to exists by definition, which is then used to say that God exists in reality as well.

Following a period during which the criticisms of Aquinas had rendered the ontological argument almost moot, interest in it during the early Enlightenment era began to rise. The argument was heavily developed by Rene Descartes. Descartes began his argument