Vigorous Fodorian criticism may make it seem impossible for Inferential Role Semantics (IRS) to accommodate compositionality. In this paper, first, I introduce a neo-Fregean version of IRS that appeals centrally to the notion of rationality. Second, I show how such a theory can respect compositionality by means of semantic rules. Third, I argue that, even if we consider top-down compositional derivability: a) the Fodorian is not justified in claiming that it involves so-called reverse compositionality; and b) a defender of IRS (...) can still offer a satisfactory account in terms of the inferential capacities of rational thinkers. (shrink)