  Behaviorism has offered recent theorists of cognitive development a way to be strongly empiricist without appealing to Locke’s inner theater of the mind. The behaviorist program was, however, dealt a major setback when Noam Chomsky, in his review (1959) of Skinner’s Verbal Behavior (1957), argued successfully that no purely behaviorist account of language-learning is possible. Chomsky’s alternative, a theory of Universal Grammar, which owes some of its inspiration to Plato and Descartes, has made the idea of innate language structures, and perhaps other cognitive structures as well, seem a viable alternative to a more purely empiricist conception of cognitive development.