Descartes challenged himself to know that he was not dreaming, with the supposed price to be paid if he lacked that knowledge being his failure to have any knowledge at all of the contingent existence and features of an external world. And subsequent epistemologist after subsequent epistemologist has kept that Cartesian skeptical challenge alive. Recent non-skeptical responses to it — most notably, Robert Nozick's — have focussed on whether one's not knowing that one is not dreaming really does entail one's lacking all external world knowledge. Seemingly, Nozick is unworried by the prospect of one's never knowing that one is not dreaming. He does argue that no one ever has that knowledge, but he reassures us that this does not entail that people do not have a steady and satisfying supply of the more ‘Standard’ sorts of external world knowledge. As I will argue in this paper, though, I see no good reason to concede in the first place that one cannot know that one is not dreaming.
