By Chris Giles
Published: May 24 2003 5:00 | Last Updated: May 24 2003 5:00
I have always been agnostic, but as I grow older I feel more uncomfortable about sitting on the fence. What would you advise?
-- Mr A. H., Birmingham
Dear Mr A.H.,
First, consider Blaise Pascal, the 17th-century French mathematician who came up with the rational basis for a belief in God, or "Pascal`s wager". It works like this: assume there are two possible states of the world, God exists and God does not exist, with an unknown probability for each. You can choose whether to believe or not and being rational, you will want to maximise your expected utility. If your belief in God is justified, you will gain infinite utility from salvation. If God does not exist, you merely bear the unnecessary finite costs of your beliefs, such as the time wasted worshipping a non-existent deity. So long as the probability of God`s existence is positive, your expected utility is infinite. If you do not believe, you will benefit if you are proved correct, and lose if proved wrong, but the important fact is these returns are finite, so your expected utility is also finite. The solution to Pascal`s wager, therefore, is that rational people should believe in God, as this is the only route to infinite utility.
Game theory, however, says a belief in God is not the only rational strategy. There is also what is known as a "mixed strategy". Instead of deciding whether to have faith in God at the outset, you could determine your belief on some random event, such as the toss of a coin. Do the maths and you will soon see that half of the time your expected utility is infinite, and the other half of it is finite. Half of infinity is still infinity so this mixed strategy is just as good as a simple belief in God. This is not just a theory. People run their lives by mixed strategies. How many times have you heard someone cry, "Yes, there is a God!" after some happy random event such as a lottery win? Agnosticism is equal to a mixed strategy before your ultimate choice, and is therefore entirely rational. I cannot think of a sounder justification for your beliefs. Keep sitting on the fence, for now.
This week`s economist is Chris Giles, the FT`s leader writer on economics.
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