Philosophy - The Ontological Argument

God's existence can be deduced from Anselm's definition - and once God has been correctly defined, there can be no doubt that he exists.

A priori - requires logical deductions not experience 

Deductive - If the premises are true, then the conclusion is true

God's existence is a necessary truth not a contingent one

'God is a being than which nothing greater can be conceived'

'Only the fool says there is no God' - (Psalm 14:1) with reference to this - Anselm said that with this definition even the fool understands this in their mind.

If God is the greatest, then it must be something that exists not just in our thoughts but also in reality.

e.g. When a painter paints a picture, they visualise it in their mind, but it is also there in reality.

The doubter must have a concept of God in their mind to reject or doubt - this means that the doubter is saying 'God who exists, does not exist' - therefore it is irrational to say God doesn't exist.

Just because an argument is deductive doesn't make it sound - it could be valid, but an unsound argument

• The Perfect lost island - Where nothing greater can be conceived.
• Gaunilo is saying that Anselm's argument is - Reductio ad absurdum (Argument of absurdity) - the argument is presented in such a way that an absurd conclusion is reached to prove that original claim must have been wrong
• To Gaunilo - the real fool would be anyone who argued in this way.

Anselm's reply

There is a difference between necessary and contingent existence 

• Everything in the universe is contingent - it has a beginning, cause and end - however only God is a necessary being - doesn't require something to cause it to exist.
• Therefore Gaulino's argument is invalid as the island is made of contingent things e.g. you could keep repairing it, but eventually all the original properties would be lost. 
• The island would need to be 'an island than which no greater can be conceived'

Directed not at Anselm but Decarte - but can be used 

1. Existence is not a predicate - as it adds nothing to the concept of the thing - Real predicates give us new knowledge of a subject.

• Just by saying 'it exists' tells nobody the nature of 'it'  
• God is the greatest conceivable being - Omnipotent, Omniscient, Omnibenevolent - they all add to the concept - saying 'God exists' adds nothing.

2. We can say God exists necessarily but this doesn't mean he exists in reality.

• God exists necessarily - is analytic - true by definition
• By saying God exists necessariiy - which Anselm claims is analytic / true by definition - I can only know this by experiencing God through my senses (e.g. a bachelor is an unmarried man)
• God existing necessarily is logically true, because we have defined God - but this does not mean there really is a God.

For Kant, knowledge is based on experience - God is beyond our experience - it would therefore be impossible for us to develop an 'a priori' definition of God.

For Kant, all claims must be synthetic - there can be no analytic demonstrations concerning the existence of God.

However it is not possible for 'God to exist necessarily' and be a synthetic statement - as there is no way of us experiencing this - it has to be an analytic statement - but no analytic statement can tell us about God's existence.

'God being a necessary being' is a 'miserable tautology' - not a proof of anything.

Strengths

• It's a Deductive argument - doesn't require any observation - also human observation is not always reliable.
• There is no ambiguity - the argument fails or succeeds by its logic
• Karl Barth - Anselm never intended to prove God's existence - rather the result of a Religious Experience - the definition is an expression of faith.

 Weaknesses

• Kant - Existence is not a predicate
• Existing necessarily does not show that God exists in reality 
• Any attempt to define God would limit God - anything that can be classified or analysed can be understood by humans - therefore Anselm's definition must be wrong - we still do not know God's definition.

A thing may be conceived in 2 ways: when the words signifying it are conceived & when the thing itself is understood.

e.g. 'fire is water' - anyone can understand the words - but someone who really understands both will have trouble understanding how fire can be water.

Applied to Anselm

The God, Atheists don't believe in, is not the same God Christians believe in. The Atheists don't have an adequate concept of God. 

However the Atheists might return this to say - how does Anselm know that his idea of God is inadequate.

However good the definition is, it still doesn't say whether such a being exits in reality.

• Anselm's argument is about faith not logic. Barth created an argument Anselm didn't need.
• Anselm's belief in God comes from reasoning - the definition was given to him through a Religious experience with God.
• If humans could prove God's existence through logic - we would not need God's revelation - as we would know God is there - we would lose all aspect of faith - God would just become an object of knowledge.

Criticisms 

• If Anselm never intended the argument to be proof, why does he go into so much detail to prove his argument is true about God
• Gaunilo - responds saying if his argument was about faith he wouldn't bother criticising it - Gaunilo criticised the argument as Anselm thinks its a logical proof - that is where the argument fails.
• Fideism - faith does not depend on reason - they reject any attempt to confine God within a system of logic.
• Anselm is seeking for Logical proof of God's existence - he's not replacing faith with logic.