 Some of the deepest divides in contemporary philosophy concern the limits of empirical inquiry, the status of conceptual analysis, and the nature of philosophy itself (see, e.g., Chalmers 1996, Jackson 1998, DePaul &amp; Ramsey 1998, Block &amp; Stalnaker 1999, Williamson 2007, Stich 2012, Machery 2017, Strevens 2018). And concepts are right at the center of these disputes. For many, philosophy is essentially the a priori analysis of concepts, which can and should be done without leaving the proverbial armchair. We’ve already seen that in the paradigm case, an analysis embodies a definition; it specifies a set of conditions that are individually necessary and jointly sufficient for the application of the concept. For proponents of traditional conceptual analysis, the analysis of a concept is successful to the extent that the proposed definition matches people’s intuitions about particular cases, including hypothetical cases that figure in crucial thought experiments.