Suppose you are not sure whether all ravens are black. If you see a white raven, that clearly refutes the hypothesis. And if you see a black raven, that supports the hypothesis in the sense that it increases our confidence, maybe slightly. But what if you see a red apple – does that make the hypothesis any more or less likely? This question is the core of the Raven paradox, a problem in the philosophy of science posed by Carl Gustav Hempel in the 1940s. It highlights a counterintuitive aspect...