Ontological argument

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  • Created by: lydia
  • Created on: 07-04-14 18:18


·         ‘ontological’ comes from two Greek words – ontos meaning ‘being’ and logos meaning ‘study of’.

·         Thus the ontological argument claims that by studying God’s being or nature we can prove that God exists.

·         It is an a priori argument as it uses logic only and requires no empirical evidence.

·         It uses deductive reasoning because the conclusion follows necessarily from the premises.

·         It is also an analytic argument because it seeks to show that the statement ‘God exists’ is true by definition.

·         first proposed by St. Anselm in the The Proslogion. He begins by reflecting on a psalm from the Bible which says that ‘Fools say in their hearts, “There is no God”’ (Psalm 14: 1).

·         Anselm believed that even ‘the fool’ (i.e. the atheist) must agree that the concept ‘God’ implies the greatest being imaginable. This, he argues, is all that is needed to prove that God exists.

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Anselm’s argument – The First Form

Anselm put forward two closely related arguments. Both follow from the definition of God as ‘a being than which nothing greater can be conceived.’ His first argument can be summarized like this:

1. God is the greatest possible being (nothing greater can be conceived).

2. God may exist in the mind alone (just as an idea) or in reality as well.

3. Something which exists in reality and the mind is greater than something which exists just as an idea in the mind.

4. Therefore, God must exist in reality and in the mind.

Clearly, the key part of this argument is that it is greater for something to exist in reality rather than just being an idea in our minds. This seems to be a very reasonable claim when we consider things like winning the lottery, having food to eat or meeting our perfect partner.

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The Second Form

Anselm developed his argument by proposing that it is impossible to conceive of a God not existing. In other words, God has necessary existence and is therefore greater than a being that comes and goes out of existence.

1. God is the greatest possible being that can be conceived.

2. It is greater to be a necessary being (cannot not be) than a contingent being (can cease to exist).

3. If God is the greatest possible being, He cannot be conceived as not existing.

4. Therefore God exists necessarily.

In summary, Anselm’s second form asserts that it would be a logical contradiction to claim that God does not exist if he has necessary existence.

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Gaunilo - On behalf of a fool

  • Following the rules of Anselm’s ontological argument, it should be possible to prove that ‘the perfect island’ exists.

– The perfect island is that than which nothing greater can be thought

– A real, existent island is greater than an imaginary island

– Therefore the perfect island must exist

• Yet, in truth it does not.

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Anslems retort

•BUT-  God is a necessary being(a necessary being must exist)

 •Existence is part of the concept of God

•An island is contingent(doesn’t have to exist), not necessary – you cannot compare the two things as they aren’t the same.

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Descartes Ontological Argument

Rene Descartes proposed an argument that is similar to Anselm’s but focuses on God as the ‘supremely perfect being’ rather than ‘greatest possible being’:

1) God is the supremely perfect being

2) A supremely perfect begin contains all supreme perfections

3) Existence (as wells as omnipotence, benevolence, omniscience etc.) is a supreme perfection

4) Therefore God, as the supremely perfect being, must exist

Descartes argued that it is more perfect to exist than be imaginary and so it follows that existence must be a predicate of the supremely perfect being.

Descartes also agreed with Anselm on the type of existence that God has – a necessary existence. It is impossible to imagine God not existing.


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Kant's Criticisms

  • ‘Existence’ is not a real predicate. Purpose of a real predicate is to provide some extra – or useful – information about the subject it describes. For example, describing God as omnipotent and omniscient expands our understanding of what God is like – we know that he is all-powerful and all-knowing. However, unlike real predicates, existence doesn’t add anything to our understanding of God, it just tells us that God is. Thus adding ‘existence’ to a concept does not make it any ‘greater’ or ‘more perfect’ (as Anselm and Descartes claim). Existence is not a great-making quality.

  • The statement ‘God exists’ can be denied without contradiction. Given that necessary existence is part of the concept of God, it appears a logical contradiction to say: ‘God does not exist’. This would be like saying ‘a triangle does not have three sides’. However, Kant argued that there is no contradiction if you rejected both subject and predicate: ‘It would be self-contradictory to posit a triangle and yet reject its three angles, but there is no contradiction in rejecting the triangle together with its three angles.’

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