 Some will expect that an account of ability would also be an account of what it is to know how to perform an action, on the supposition that one knows how to perform a certain action just in case one has the ability to perform that action. This supposition, which we may call the Rylean account of know how (since it is most explicitly defended in Ryle 1949, 25–61), has been called into question by Jason Stanley and Timothy Williamson (Stanley and Williamson 2001). Let us briefly consider Stanley and Williamson’s argument and how it bears on the theory of ability.