1. Gaunilo’s response the stage one of Anselm’s argument
Gaunilo of Marmoutier, a fellow Benedictine monk, criticised Anselm’s ontological argument. He uses the example of a perfect island. He argues:
‘Now if someone should tell me that there is such an island, I should easily understand his words, in which there is no difficulty….you can no longer doubt that this island which is more excellent than all lands, exists somewhere, since you have no doubt that it is in your understanding. And since it is more excellent not to be in the understanding alone, but to exist both in the understanding and the reality, for this reason, it must exist.’

2. What shall I have on my perfect island?

3. Gaunilo essentially argued that you could argue that anything has necessary existence if you conceive of it as the greatest possible thing in your head.
This would allow it to be thought of as necessarily existing so as to make it the greatest.
Therefore the greatest possible island has to exist necessarily which, says Gaunilo, is an absurd thing to say, thus refuting Anselm’s ontological argument.
Or so he thought…

4. Anselm’s second stage of the ontological argument…
You can’t use this argument here!! An island is a contingent thing – it can be thought of not existing. God is a necessary being!
Essentially Anselm denied that the argument could be used for anything other than that which has necessary existence – God

5. Descartes used the definition of God as the ‘supremely perfect being’
Rene Descartes –
Ah, Monsieur Anselm, I agree with you! I have my own version of the ontological argument, again based on definition, and also an ‘a priori’ argument. It’s a winner!!
Descartes used the definition of God as the ‘supremely perfect being’

6. As a supremely perfect being, God must necessarily possess all possible perfections, amongst which there has to be the perfection of existence.
A being that failed to exist could not be classed as perfect as the being that had non-existence as an impossibility
Existence, therefore, must be a necessary attribute of the perfect being
He uses the example of a triangle to illustrate his argument…

7. In order to be a triangle, a shape must have three sides and three angles that add up to 180 degrees.
To try and imagine a triangle without the predicate of 3 sides and 3 angles adding up to 180 degrees would be illogical. Just as illogical as it would be to try and imagine God without the predicate of existence. The prefect being requires the predicate of existence.

8. Immanuel Kant: an objector
He responds to Descartes’ ideas by using the triangle illustration against him. He argues that to remove the predicates of the triangle and still have a triangle would be a contradiction but if you remove the idea of the triangle in the first placed then there is no contradiction. The predicates of a triangle do not require it to exist. Neither do the predicates of God.

9. Kant continued…
He also argued against Anselm and his idea that existence is a predicate of the greatest possible being ever conceived. To ‘exist’ is not a predicate; it does not tell us anything about God, whereas ‘God is female’ would – that it a predicate.
He goes on to argue that this predicate of existence actually gives Anselm a problem. If we accept that ‘existence’ is a predicate and tell us about a property of God then the phrase ‘God does not exist’ suggests that God does not have this property. How can something that does not exist ‘lack’ something? Especially when it something that should be existing necessarily!!!