I argue that the open question argument and Frege’s puzzle (understood as a reductio of Millianism) are variants of the same argument. Once the parallel is appreciated, much of the standard commentary on the open question argument and its role in the case for nonnaturalism is inadequate. Not only do we learn something about the open question argument, but so too do we learn something about Frege’s puzzle: I argue that both are unsound for the same general reason.Article