For nearly four centuries, our understanding of human development has been controlled by the debate between nativism and empiricism. Nowhere has the contrast between these apparent alternatives been sharper than in the study of language acquisition. However, as more is learned about the details of language learning, it is found that neither nativism nor empiricism provides guidance about the ways in which complexity arises from the interaction of simpler developmental forces. For example, the child's first guesses about word meanings arise from the interplay between parental guidance, the child's perceptual preferences, and neuronal support for information storage and retrieval. As soon as the shape of the child's lexicon emerges from these more basic forces, an exploration of "emergentism" as a new alternative to nativism and empiricism is ready to begin.