1 oct. 2011

Le pari de Pascal

Although I reject Pascal's wager, for the reasons I explained in the last post, it must be said that Pascal was a brilliant mathematician and that his idea is one of the first applications (if not the first, I really have no idea) of game theory to theology.

Suppose you had to calculate the probability of there being a Christian God who would send an non-believer to hell automatically. Someone living in Pascal's time and place would probably think that was fairly probable, even if not certain. Even if someone had some doubts, the typical 17th century Frenchperson probably wouldn't put the probability at zero. So the question is how low the probability would have to be to simply take the risk. Imagine a game of Russian Roulette. Suppose the revolver had, not six chambers, but 100. Would you play? How about 1,000? 10,000? If the revolver has two chambers, with a bullet in one of them and not the other, almost nobody would play Russian Roulette with it, or if three of the six chambers contained bullets.

So for people raised on hellfire and damnation, Pascal's bet might seem like a pretty good deal. Why wouldn't you refuse to play Russian Roulette with the fate of your eternal soul? Remember, according to Pascal, you lose nothing by believing, even if you are wrong.

The fallacy comes in thinking that the religion that your parents or your community happened to use to put the fear of God (so to speak) in you as a child has more probability of being true than any other one. In other words, if you were a Hindu raised in India you would vastly overrate the probability of Hinduism being the true religion. It is easy to see that for Hinduism, but much harder to see that from within one's particular culture. So really one would have to place bets on different horses, not just one, and then the whole scheme falls apart. Remember that believing in the wrong God is an explicit violation in the monotheistic traditions.

(For example, how do I know for a fact that the ancient Egyptian Gods are not the ones really in charge up there? It seems ridiculous to even pose the question, but that is simply because there are no ancient Egyptians anymore. How would I evaluate betting for or against the existence of Egyptian Gods? For me, that gun has no bullets, so I don't even worry about it.)