ABSTRACT
It is natural to think that, if the man has an 80% chance of having correctly identified the colour of his assailant, and claims he was mugged by a black man, he is more likely to be right than wrong. But, on the contrary, he is more likely to be wrong than right, for his chance of being right is only 4⁄13. That is the probability that the assailant was black given that he was identified as black.
