I argue that there are analytic claims that, if true, can be known a priori, but which also can turn out to be false: they are expressive of merely default instructions from the language faculty to the conceptual system, which may be overridden by pragmatic or scientific considerations, in which case, of course, they would not be known at all, a priori or otherwise. More surprisingly, I also argue that they might not be, strictly speaking, conceptual: concepts may be importantly different from the meaning instructions for the words we use to express them. I will press all this in the context of a general Quinean “naturalism,” where the epistemology that interests me is “a chapter of natural science,” but where the science won\u27t be Quine\...