The well-attested friction between linguistics and psychology is not a superficial phenomenon. No conception of language has had more influence on psychology and Cognitive Science than the linguistics of Noam Chomsky. Yet Chomskyan linguistics is radically incompatible with viable accounts of knowledge, and of the development or evolution of knowledge. This incompatibility is strongly manifested in two characteristic Chomskyan doctrines: linguistic competence and the autonomy of syntax. The fallacious arguments on which Chomsky relies are analyzed, and their deep implications for Cognitive Science are traced.