This paper discusses the role that appeals to theoretical simplicity have played in the debate between nativists and empiricists in cognitive science. Both sides have been keen to make use of such appeals in defence of their respective positions about the structure and ontogeny of the human mind. Focusing on the standard simplicity argument employed by empiricist-minded philosophers and cognitive scientists—what I call “the argument for minimal innateness”—I identify various problems with such arguments—in particular, the apparent arbitrariness of the relevant (...) notions of simplicity at work. I then argue that simplicity ought not be seen as a theoretical desideratum in its own right, but rather as a stand-in for other desirable features of theories. In this deflationary vein, I argue that the best way of interpreting the argument for minimal innateness is to view it as an indirect appeal to various potential biological constraints on the amount of innate structure that can wired into the human mind. I then consider how nativists may respond to this biologized version of the argument, and discuss the role that similar biological concerns have played in recent nativist theorizing in the Minimalist Programme in generative linguistics. (shrink)