Is knowing-how simply a case of knowing-that?

Jason Stanley and Timothy Williamson have argued that there is no fundamental distinction between what Gilbert Ryle famously called 'knowing how' and 'knowing that', and that the former can be treated as a special kind of the latter. I will endeavour to show that sentences of the form 'a knows how to F' are ambiguous between a reading in which we ascribe knowledge-that to a and another in which we ascribe something to a which is irreducible to any kind of knowledge-that and can most appropriately be characterized as an ability. The authors' attempt to reduce also the latter reading to an ascription of knowledge-that fails because it rests on an unexplained conception of practical modes of presentation.