 What Austin says here is consistent with the operation of the capacities being reliable in some circumstances, and with their reliable operation being such as to give rise to knowledge. So it is open to Austin to hold a view on which knowledge requires that the particular exercises of the capacity to judge on which they are based couldn’t have occurred and yet the output judgment be mistaken. And it is open to him to hold that if the exercise of judgmental capacities is to give rise to knowledge, those capacities must be reliable in the circumstances in which they are exercised and given the way they are exercised on that occasion (e.g., carefully). However, Austin doesn’t make fully explicit that his view about knowledge includes either component. And some of what he says—especially in discussion of his performative proposal about the use of “I know”—is in tension with the first claim, on which knowing is incompatible with being  mistaken.[20]  (It’s possible that Austin viewed his “Ifs and Cans” (1956a) discussion of abilities as providing further illumination concerning the proper understanding of the formula “If one knows, one can’t be wrong”.)