feotakahari

This is Saint Anselm’s argument for why God must exist, as copied from Wikipedia:

1. By definition, God is a being than which none greater can be imagined.
2. A being that necessarily exists in reality is greater than a being that does not necessarily exist.
3. Thus, by definition, if God exists as an idea in the mind but does not necessarily exist in reality, then we can imagine something that is greater than God.
4. But we cannot imagine something that is greater than God.
5. Thus, if God exists in the mind as an idea, then God necessarily exists in reality.
6. God exists in the mind as an idea.
7. Therefore, God necessarily exists in reality.

This is a very easy argument to parody, e.g. Gaunilo’s “perfect island”, but it’s much harder to disprove. Writers as recent as Bertrand Russell had a hard time explaining exactly why it’s wrong.

To take my own crack at it, I’d like to start by limiting proposition 6:

“A being that is or resembles God exists in the mind as an idea.”

The being in your mind may not be a perfect representation of what God is! God isn’t necessarily a bearded old man, or a dark-skinned young woman, or three circles of yellow light rotating through each other that are somehow all the same circle. If there is a God, He exists regardless of whatever frame of reference you can or can’t fit God into.

This does not undermine propositions 1 or 2. For the purposes of this argument, I cede that if there is a God, there is nothing greater than Him, and that any human idea of what God might be cannot be greater than the actual God.

From here, proposition 3 is looking less and less relevant. If we don’t know whether the idea in our heads is God, how can we evaluate whether it’s lesser or greater than God? We would have to compare it to some guaranteed accurate idea of what God is like, and we can’t be sure we have that! To salvage anything from proposition 3, it needs to be reworked: 

“If God exists in reality, then the real God is greater than any godlike being that only exists in the mind.”

Even from here, there’s no logical way to get to proposition 7! All we’ve proved is a point of linguistics: 

“A being that does not exist in reality cannot be called God.”

Anselm’s trick, as I see it, was switching from talking in hypotheticals (“This is what God would be like if I observed Him”) to talking as if he’s seen God and taken observations (“This is what God is like.”) In effect, Anselm hid the hypothetical behind a curtain and pretended to have created observations from nothing.

(The last time I went into this, I was told Kant had the same idea centuries ago in his Critique of Pure Reason. I looked it up, and it’s way above my experience level. I think the argument there is that proposition 2 is begging the question by assuming there’s such a thing as “necessary existence.”)