Texas sharpshooter

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The famous fallacy of probabilistic reasoning. A form of confirmation bias.

If you happen upon an event which, in the abstract is highly improbable at random, there is a tendency to impute foul play. But at the point where the event has already happened it is not a random event but history. Treating it as a contingency can be misleading.

Predicting that a Mr Bentos of Cheltenham will win next week’s lottery is hard. Predicting that he won last week’s is a cinch.

This can put people in jail who should not be (Sally Clark), keep out of jail people who should be in (O. J. Simpson), and confuse the hell out of creationists. Evolution by natural selection is a form of inverse sharpshooter exercise, whereby you deliberately exclude all the bad shots. You only need a few lucky good ones for it to work, and no-one gets the credit for it.

Sorry, Baby Jesus.

See also

• Lucy Letby
• Confirmation bias
• Evolution by natural selection
• Bayesian priors