We focus on Timothy Williamson’s recent attack on the epistemological significance of the a priori–a posteriori distinction, and offer an explanation of why, fundamentally, it does not succeed. We begin by setting out Williamson’s core argument, and some of the background to it and move to consider two lines of conciliatory response to it—conciliatory in that neither questions the central analogy on which Williamson's argument depends. We claim, setting aside a methodological challenge to which Williamson owes an answer, that no satisfactory such reconciliation is in prospect. Rather, as we then argue, —and it is on this that we base our overall negative assessment of his argument—Williamson’s core analogy is flawed by an oversight. We conclude with some brief reflections on Williamson’s ideas about the imagination as a source of knowledge. Our principal conclusion is only that Williamson’s argument fails to perform as advertised. A constructive case for confidence, to the contrary, that the intuitive contrast between a priori and a posteriori reflects something of fundamental epistemological significance is prefigured in our final section, but will not be elaborated here.