Abstract
Hume's two definitions of causation have caused an extraordinary amount of controversy. The starting point for the controversy is the fact, well known to most philosophy undergraduates, that the two definitions aren't even extensionally equivalent, let alone semantically equivalent. So how can they both be definitions? One response to this problem has been to argue that Hume intends only the first as a genuine definition—an interpretation that delivers a straightforward regularity interpretation of Hume on causation. By many commentators' lights, however, this is a bug rather than a feature: such an account of the two definitions leaves necessary connection out of Hume's story about the meaning of "cause" ..