Ontological Argument Criticisms

1. God is the greatest conceivable being.

2. God could exist in realiity or only in my mind.

3. It is better to exist in reality, and as God is the greatest possible being, he must therefore exist.

4. It is illogical to deny God's existence if you accept each stage of this argument.

Gaunilo criticised Prosologian 2:

1. You cannot define something into existence. Having an idea of something does not mean it exists.

2. Gaunilo's Island - just because I can imagine the perfect island, doesn't mean it exists.

Plus, my neighbours perfect island is different to mine - would that mean they both exist? Would everybody's different definitions of God exist?

Anselm responded to Gaunilo's Island criticism with Prosologian 3:

1. God is the greatest possible being

2. It is better to be necessary than contingent

3. God must be a necessary being as otherwise a necessary being could be imagined which would be greater than God.

4. God must be necessary. 

The island is contingent and God is necessary - the two are not comparable.

Platinga - supports Anselm - the island has no intrinsic maximum, but God is maximally great.

1. I have the concept of a perfect being

2. Since I am imperfect, I could not have created this concept of a perfect being

3. The concept must have originated from the perfect being itself

4. The perfect being, which is God, must exist

1. The idea of God is a supremely perfect being

2. A supremely perfect being must have all perfections

3. Existence is a perfection

4. The suprememly perfect being must have the perfection of existence

5. God exists.

If God did not exist, he would not be perfect, existence is a predicate of God. To deny God's existence is as illogical as denying a triangle has 3 sides.

Malcolm supports the Ontological agument.

1. God could be either necessary or impossible

2. If God doesn't exist now, he never can, as that would imply something greater than God causing his existence.

3. If God does exist now, he must be necessary, since contingency would imply a greatre being. 

4. So God either exists necessarily or his existence is impossible.

5. It is not illogical for God to exist, so his existence is not impossible.

6. Therefore, he must exist necessarily.

1. Existence is NOT a predicate. Predicates give information, and you can lack predicates. Existence is not a predicate, it is what the predicates rely on. You cannot 'lack' existence, you just don't exist.

2. Logic should only be used for maths and science. Arguments for the existence of God should be synthetic and use empiricism.

3. Existence does not add to the perfection of something - as Descartes suggests.

4. If the word 'God' means 'an existing being' as Anselm and Descartes suggest, then when we say 'God exists' it is a tautology and is therefore illogical:

                              'God exists' = 'an existing God exists'

Aquinas - we don't know God's nature, so we cannot know that 'God exists' is the analytical statement it claims to be.

Gassendi - Perfection can only be discussed if God exists. If he doesn't exist, he is not perfect OR imperfect - he just doesn't exist!

Russell - Existence is not a predicate. This is like saying,

Donkeys exist. Eeyore is a donkey. Eeyore exists.

Davies - There are two uses for the word 'is'. One means that something exists, the other describes the nature of something. You cannot logically mix the two uses of 'is' and this is what the Ontological argument does.

                 God is necessary               =                     God is

                     ^ describing the nature                               ^God exists