The ontological argument Anselm, Descartes, Malcolm and Plantigna

Descartes’ Version God is defined as perfect. If God did not exist he would not be perfect.

Anselm version 1 Even the fool of Psalm 14 understands that the idea of God is…. ‘that than which nothing greater can be conceived.’ Either; God exists only in the mind, or God exists in the mind and reality. As premise 1 is greater than premise 2 it must be correct according to our definition.

Anselm’s argument Analytic sentences – A priori - are true by definition – there is no need for empirical proof. Synthetic statements – A posteriori - these are proved true or false using empirical observation.

Gaunilo The prefect holiday island. Using Anselm’s logic we can conclude that the perfect holiday island must exist, but we know that it doesn’t. Therefore Anselm’s argument doesn’t work.

Aquinas’ critique We do not agree on a definition of God. E.g. Some take him to have a body, some say he is a spirit. God’s nature is beyond human understanding and so cannot be proved with our flawed logic. Video link

Hume and Kant Essentially they say the same thing – empirical evidence is needed to establish whether a thing exists. Hume: All existential statements are synthetic Kant: Existence is not a predicate.

Anselm’s second version Contingent existence – things which do exist but did not have to, i.e. all the object in the world, the universe itself. Necessary existence – a form of existence where it has to exist. As necessary existence trumps contingent in terms of greatness, by definition God must exist necessarily.

Norman Malcolm adds Look at the statement ‘God necessarily exists’. The truth of it is either: Impossible Possible Necessary

Impossible existence The existence of anything is only impossible if by definition it is a logical contradiction. A triangle has 4 sides is a logical contradiction and therefore impossible. ‘God necessarily exists,’ does not contain a logical contradiction, therefore we can rule this out as a solution.

Is God’s existence possible? By possible we mean contingent. God could exist or not exist, it is not essential that he does, just like the existence of this powerpoint. Malcolm maintains that by the definition given this is not the type of existence God has. The conclusion is that necessary is the only option left.