The Ontological Argument

This morning, I received the following email from a friend of mine.

Hi Gem,

My friend claims the following is a proof of God's existence. What do you think? It's not convincing to me, but I don't have much experience in recognizing logical fallacies. Could you help me out?

***
God is defined as THAT WHICH NONE GREATER CAN BE THOUGHT.

THAT WHICH NONE GREATER CAN BE THOUGHT can be thought of as existing only in the understanding. [This means THAT WHICH NONE GREATER CAN BE THOUGHT does not exist outside of the understanding (reality for example)].
"THAT WHICH NONE GREATER CAN BE THOUGHT conceived as existing only in the understanding" can be thought as greater still, "THAT WHICH NONE GREATER CAN BE THOUGHT existing in reality."
This creates a contradiction, THAT WHICH NONE GREATER CAN BE THOUGHT by definition cannot be thought as greater. Therefore, THAT WHICH NONE GREATER CAN BE THOUGHT cannot exist only in the understanding.

If P (that which none greater can be thought existing only in the understanding) then Q (that which none greater can be thought existing not only in the understanding) is not Q [because that which none greater can be thought can be thought as greater). Therefore P is false.

Note: this does not prove the Christian God or any known deity. It simply proves the existence of THAT WHICH NONE GREATER CAN BE THOUGHT. Whether THAT WHICH NONE GREATER CAN BE THOUGHT created humans or even cares about us cannot be determined. We simply know that there is something of such greatness that cannot be exceeded.
This may require modal logic to distinguish from Necessary Truths and Contingent Truths.
***

[NAME REDACTED]

"THAT WHICH NONE GREATER CAN BE THOUGHT"? Good lord.

My reply follows.

Hi, [NAME REDACTED].

Your friend is presenting the Ontological Argument, first proposed by Anselm of Canterbury, championed by Réné Descartes, and recently revived by Alvin Plantinga. After Pascal's Wager, it is probably the most widely criticised (and even ridiculed) of the philosophical arguments for the existence of a deity, because it attempts to quite literally define God into existence.

Your friend's argument is phrased more along the lines of Anselm's original argument (although more awkwardly). In my reply, I'll refer to the following, more readable, ontological argument:

1. God is the greatest imaginable entity.
2. All else being equal, an entity that exists is greater than one that doesn't.
3. ∴ God exists.

The problems with this argument are legion. Although the applicability of some of these objections is dependent on the wording of the argument, I believe that every proposed ontological proof has been adequately dealt with.

We'll begin with a point originally raised by Gaunilo of Marmoutiers: an argument with the same logical structure can be repurposed to apply to just about anything. Take the following ontological proof, for example:

1. Atlantis is the greatest imaginable island.
2. All else being equal, an island that exists is greater than one that doesn't.
3. ∴ Atlantis exists.

Or this one:

1. The minotaur is the greatest imaginable animal.
2. All else being equal, an animal that exists is greater than one that doesn't.
3. ∴ The minotaur exists.

Other philosophers, such as Immanual Kant (the great pissant), have objected that existence and non-existence are not properties as such, and in any event no rationale is presented for the supposition that existence is "greater" than non-existence. Personally, I would add that the argument assumes that "greatness" can be quantified and that it exists objectively, rather than simply being a subjective assessment of value or worth. If you believe that greatness is objective, what is the greatest colour?

But let's look at this from another perspective: does God taste good on a sandwich?

For the sake of argument, let's say that "THAT [THAN] WHICH NONE GREATER CAN BE THOUGHT" doesn't taste very good on a sandwich. But this presents a problem, because it would be greater still if it did taste good on a sandwich. Therefore, God is an excellent condiment.

Unfortunately, I can't take credit for this line of reasoning. While discussing this argument on The Atheist Experience, Russell Glasser had this to say: "I like Jeff Dee's comment on this argument... It's kind of silly to say that perfect things have every good quality. You know, by that logic, God should be an excellent floor polish, and putting him on your ribs should make them taste extra delicious."

This argument may also be guilty of begging the question: the first premise defines God as the greatest conceivable being; however, since the argument also states that the property of existence is required for the being to be of maximal greatness, the argument is actually in essence this:

1. God is defined as the greatest imaginable entity, which exists.
2. By premise 1, God exists.
3. ∴ God exists.

And finally, as your friend pointed out, the argument doesn't actually say anything about God. Other than that he is awesome, and that he exists.

I hope that this helps, [NAME REDACTED]. All the best.

Gem