Abstract
This chapter examines two different views of universal grammar. Most linguists assume that universal grammar is underspecified — providing us with an incomplete grammar to be elaborated by learning. But the alternative is that it is overspecified — providing us with a full range of possible grammars from which we select one on the basis of environmental input. Underspecification is now the dominant view in the developmental sciences, and is often treated as the null hypothesis on grounds of greater possibility, parsimony, and simplicity. The chapter questions whether the underspecification view is really feasible and whether it is more parsimonious than the overspecification view, drawing on examples from certain African languages. It also shows that the perplexity evoked by overspecification theories disappears if language has a concealing purpose as well as a communicating purpose, similar to a code.