Anselm's Ontological Argument

Around 1100 AD, the theologian/philosopher, Anselm, proposed the following set of propositions which seem to flow logically and prove the existence of god. This was among the first (of many) "ontological arguments" for the existence of god. Ontological, in this context, means the use of logic to prove that god is metaphysically necessary. In other words, using pure logic to show that there is no alternative to god's existence:

1. Our understanding of God is that he is a being, a being greater than any other being that can be imagined or conceived.
2. The idea of God exists in the mind.
3. A being which exists both in the mind and which exists in reality is greater than a being that exists only in the mind.
4. If God only exists in the mind, then we can conceive of a greater being, a being which also exists in reality.
5. We cannot be imagining something that is greater than God.
6. Therefore, God exists.

QED, right? Not so fast. This is a perfect example of Christians' slippery and dangerous use of logic to prove that their fiction is reality. This was the first of many attempts to show god to be "logically necessary". It was followed by other ontological proofs by Descartes, Kant, Leibnitz, Godel, Plantinga and many others, which I won't repeat here. They are extremely tedious and academic. However, they can easily be found here on the web if you are interested.

Immediately after Anselm presented his case, a contemporary named Guanilo showed the argument to be nonsense, or to result in absurd consequences if the same argument were to be applied to the "greatest island" or the "greatest pencil". There is an infinity of "greatest" entities that can be shown to "exist" using the above logical "recipe". This fact does not necessarily disprove Anselm, but shows that its application results in assertions that we cannot reasonably accept. For example, Guanilo's reply to Anselm was along these lines:

1. The "Lost Island" is an island greater than any other island that can be conceived, full of riches and beauty and joy.
2. It is greater to exist in reality than merely as an idea.
3. If the Lost Island does not exist, one can conceive of an even greater island - that is, an island that does exist.
4. Therefore, the "Lost Island" exists in reality.

When reduced to this trivial form, or even sillier ones such as a "greatest pencil" or "greatest bar of soap" you can easily see how what appears to be a valid and sound argument can lead you to ridiculous conclusions. Hume, Aquinas, Kant, and others have picked it to shreds, pointing out problems with several of the assumptions that go into the premises. Kant said (and most philosophers since then agree, though it continues to be contested by apologists),

‘Being’ is obviously not a real predicate; that is, it is not a concept of something which could be added to the concept of a thing.…. By whatever and however many predicates we may think a thing…we do not make the least addition to the thing when we further declare that the thing is.

In other words, existence is not a quality that something has, like size or shape or color. Existence does not add to the essence of a being, but merely indicates its occurrence in reality. Though syntactically, a statement about existence is structurally identical to to a statement attributing qualities to a thing, it is a very different type of statement. The two statements, "the tree exists" and "the tree is tall" have a similar sentence structure, but they are saying two very different types of things about the tree. Kant concluded that it is conceivable for a completely perfect being to not exist in reality - only conceptually, like a perfect triangle or Guanilo's perfect island.

David Hume argued that nothing can be proven to exist using only a priori (purely logical) reasoning. You could only prove this sort of existence if its opposite (non-existence) generated a contradiction with one or more of the premises. With the god argument from Anselm, the non-existence of a perfect being is just as viable as its existence, so the argument fails to accomplish its goal. Simply imagining a perfect being doesn't cause that being to exist. This is starting to sound like Anselm was into the same wishful thinking as followers of "The Secret" and the "Law of Attraction", who believe that if you imagine things hard enough, they become true!

Despite the deficiencies and logical shortcomings of this type of argument, early ontological arguments like Anselm's serve as a model for today's crop of apologists (such as Plantinga and Craig), who continue to defend the logical proofs for god's existence which they have derived from it and augmented with their own additions.