Is Evidence Knowledge?

In chapter 9 of Knowledge and its Limits (Williamson 2000), Timothy Williamson argues for the thesis that the evidence that a subject has is constituted by propositions known by the subject (a thesis that he summarizes in the equation E=K). Moreover, Williamson also argues that whatever justifies a subject in believing a proposition is part of that subject’s evidence, and thus that only propositions that a subject knows can justify further propositions. We will argue that such a position has two implausible consequences. First, it is incompatible with the existence of Gettier cases. Second, it entails that a plausible principle of the closure of justification fails. But there are Gettier cases, and the closure principle is true. Therefore, evidence isn’t knowledge.