Ontological argument

The ontological argument is a failed attempt to argue for the existence of God. It is a deductive argument based on the definition of God, originally proposed by Anselm and later used by Descartes. Anselm's form runs as follows:

God is the most supremely perfect being- a being with all possible perfections

It is better to exist than to not exist

Therefore, God exists

Descartes' form is similar:

God is a being with all possible perfections

Existence is a predicate of such a being

Therefore, God exists

Its deceptively simple appearance often causes confusion and a 'mental double-take' when it is first presented. It has the advantage that even atheists tend to agree with the first premise defining God, and from that follows in a strong, apprantly deductive fashion. Anselm also attempted to bypass Hume's Fork, stating that 'God exists' is a unique type of statement, as it is analytically derived, yet states something about the physical world. He called this an 'analytic existensial' statement. The claim of a 'unique' statement exempt from the laws of reasoning often causes concern about the validity of any argument including it- see also Tillich's symbolism.

Even in Anselm's day, however, problems were identified with the ontological argument. Guanilo, a contemporary of Anselm, used reductio ad absurdum and envisaged a 'lost, yet most perfect island'. Guanilo argued that just because we can imagine this island does not mean it actually exists.

Kant weighed in against Decartes' version, challenging the second premise that existence is a predicate. Kant said he could imagine a hundred thalers (coins) in such great detail that whether or not they actually existed was arbitrary, as there was no difference other than this between the imagined and the existent thalers.

Finally, Davies identified the critical failing of the argument. As presented, the argument begs the question- it assumes what it sets out to prove. Ie, if a God existed, he would be supremely perfect, and would therefore exist. In explicit form, the first premise correctly reads 'The concept of God is the most supremely perfect concept'. The ontological argument is therefore flawed in that it uses equivocation to progress from a concept of God to an existent of God to an existent God, and fatally flawed in that the entire argument collapses irreparably once this is exposed.