This paper argues against Zoltán Szabó’s claim in “Compositionality as Supervenience” that we ought to understand the principle of compositionality as the idea that in natural language, the meanings of complex expressions strongly supervene on the meanings of their constituents and how the constituents are combined. The argument is that if we understand compositionality Szabó’s way, then compositionality can play no role in explanations of the acquirability of natural languages, because it makes these explanations circular. This, in turn, would undermine (...) the primary motivation for thinking that natural language is compositional, and would thus undermine the importance of the principle in natural language semantics. Thus, even if Szabó’s reading of the principle best accords with theorists’ intuitions about what sorts of languages are compositional—as he claims it does—there is good reason to reject that reading. Finally, the paper defends the claim that we ought to think of the principle as the idea that in natural language, the meanings of complexes weakly supervene on the meanings of their constituents and how they are combined. (shrink)