As usually understood, ‘conceptual engineering’ is a form of conceptual inquiry aimed at diagnosing problems with extant concepts and finding better concepts to replace them. This can seem like an appropriate response to a skeptical concern that our concepts are cognitively deficient: unsuitable for use in serious inquiry. We argue, however, that conceptual engineering, so understood, cannot reasonably be motivated in this way. The basic problem is that on the first hand, since conceptual engineering is itself a form of inquiry, (...) it cannot succeed by using the problematic concept itself in inquiry (since it is unsuitable for use in inquiry); but, on the other hand, methods for carrying out inquiry directed at concepts without using those concepts are constrained in such a way as to make conceptual engineering very unlikely to succeed. The upshot is that conceptual engineering has no reasonable chance of addressing the skeptical concern about cognitive deficiency. This is an important and previously unarticulated result, about what conceptual engineering can and cannot reasonably be expected to do. (shrink)