Logic dictates that the two statements “All ravens are black” and “All non-blacks are non-ravens” are equivalent. The logician Carl Hempel pointed out that this equivalence suggests that the observation of a white dove serves as evidence for both statements. That means that sighting a white dove is evidence that all ravens are black. Confusing?Fear not, this paradox is resolved when we consider that not all evidence can be treated equally. The collection of all non-black non-ravens is significantly larger than the set of all ravens. As a result, the observation of a single black raven holds stronger evidence for the statement "All ravens are black" than the sighting of a single white dove. This paradox serves as a reminder to critically evaluate empirical evidence and recognize that not all evidence carries the same weight.

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