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Creationist Probability

ABC News has an article by mathematician John Allen Paulos on how creationists misuse probability in their anti-science arguments. This article is inspired by the Science article on public acceptance of evolution. I especially like how he distinguishes between a priori and a posteri probabilities:

Now if we shuffle this deck of cards for a long time and then examine the particular ordering of the cards that happens to result, we would be justified in concluding that the probability of this particular ordering of the cards having occurred is approximately 1 chance in 10 to the 68th power. This certainly qualifies as minuscule.

Still, we would not be justified in concluding that the shuffles could not have possibly resulted in this particular ordering because its a priori probability is so very tiny. Some ordering had to result from the shuffling, and this one did.

Nor, of course, would we be justified in concluding that the whole process of moving from one ordering to another via shuffles is so wildly improbable as to be practically impossible.

The actual result of the shufflings will always have a minuscule probability of occurring, but, unless you’re a creationist, that doesn’t mean the process of obtaining the result is at all dubious.

(Via 3 Quarks Daily.)