The Ontological Argument

The ontological argument (‘concerned with being’) is an a priori argument, first proposed by St. Anselm in his book ‘Proslogion’. The argument attempts to prove God’s existence by definition.

Anselm’s ontological argument

First form

Anselm began by defining God as ‘that than which nothing greater can be conceived’ (TTWNGCBC). We can all comprehend in our minds a being which is ultimately perfect. However, we can also conceive of a greater being that exists both in the mind and in reality. This being then would be greater than God. Thus, if God is that than which nothing greater can be conceived, then he must exist in reality as well as in the mind.

Second form

Anselm developed his argument by proposing that it is impossible to conceive of a God not existing. God is a necessary being – he cannot not be. If God were a contingent being (one whose existence depends on something else), he would not be the greatest since we could image him not existing. Thus, a necessary being is greater than a contingent one. If God is that than which nothing greater can be conceived then he must be a necessary being i.e. in existence.

Rene Descartes’ ontological argument

He start by stating that God is a supremely perfect being – i.e. posses all perfections. Existence is a perfection. Therefore God exists. He used a triangle to prove his point. A triangle has necessary characteristics (a predicate) such as internal angles which add up to 180 degrees. If any of these predicates are removed, the triangle is no longer a triangle. Similarly, existence is a necessary predicate of God.

Criticisms of the argument

• Gaunilo – was a monk alive at Anselm’s time. He used the analogy of the perfect island in his book ‘On Behalf of the Fool’ to illustrate the absurdity of the first form of the ontological argument. He said that if you imagine ‘the most perfect island’, then since it is perfect and existence is part of perfection then it must necessarily exist. Otherwise, the grottiest island would be better than the imaginary ‘perfect’ island.

• Anselm’s counter argument to this was that he was not arguing about contingent things such as islands, but of ‘that than which nothing greater can be conceived’. Islands have no ‘intrinsic maximum’ – they can always be bettered (since according to John Hick, notions of perfection are subjective). God is not temporal or contingent and thus his existence is necessary. Anselm formulated the second form to counter argue this specific criticism.

• Immanuel Kant – argued against Descartes’ form of the ontological argument. He says that existence is not a predicate. This is because to say that something exists makes no difference to the definition of the thing. Just because you add “and exists” to the end of the word ‘bachelor’, does not change its definition.