Is there anything wrong with using a concept C in the course of arguing against the use of C? You might think not, so long as the argumentation is framed as a kind of reductio; or climbing a ladder to be kicked away. On the other hand, you might find such “hypocritical” arguments self-undermining: if they’re sound, then we shouldn’t accept any of their premises that make use of C. Understanding the status of hypocrisy is an urgent question for conceptual ethics (and therefore engineering), insofar as concepts of philosophical interest tend to be central to our conceptual schemes, in the sense that they tend to turn up in the analyses of lots of other concepts. Developing these points (of view), the present chapter exposes a worrisome feature of the anti-hypocrisy argument just sketched: it seems to be indeterminate whether or not the argument is itself hypocritical.