 Replacement Naturalism holds that conceptual and justificatory theories—the traditional fare of philosophy—are to be replaced by empirical and descriptive theories. There are two kinds of argumentative routes to Replacement Naturalism, both traceable to Quine: the first arises from doubts about the analytic-synthetic distinction (Quine 1951); the second from doubts about foundationalism (Quine 1969). Here we consider the former.