Descartes' Ontological Argument

Descartes is a sceptic who attempted to demonstrate that it is impossible to doubt the existence of God.
His work is generally regarded as the starting point for modern philosophy.

Descartes argued that God is the supremely perfect being and that existence is a necessary part of the meaning of God. He saw existence as a perfection and therefore that God, a supremely perfect being-must have all the perfections including existence..

As with Anselm's argument, Descartes' argument relies on a definition of God, in this case that he is a 'supremely perfect being'. Descartes focuses on this concept of God and notes that a supremely perfect being would have to be perfect in every way, i.e to be all knowing, all powerful etc. To Descartes existence is a perfection just as being all powerful and all knowing are. Descartes' argument assumes that 'existence' is a predicate/quality of God and therefore based on this assumption he is able to conclude that God exists.

Kant's Criticisms:

• Kant argues that we cannot move from the realms of definitions and concepts to reality in the way that the ontological argument attempts to. It is one thing to discuss our concepts but an extremely different thing t talk about what exists in the real world.
• He goes on to say that existence is not a real predicate. He proposes that a genuine predicate is one that describes the thing we're talking about and so adds a descriptive properly to it and enhances our concept of it. However, 'existence' does not do this, it adds nothing to our concept of a subject and therefore cannot be classified as a real predicate. It is essential to Descartes that 'existence's is part of what we mean by 'God' therefore the ontological argument fails since existence is not a real predicate.