Introduction: language acquisition and relationships between language and thought

The study of child language acquisition can make an important contribution to our understanding of relationships between language and thought. In fact, controversies concerning the pre-requisites for language acquisition have a long history paralleling almost exactly the history of controversies concerning relationships between language and thought (see the Introduction to this volume). In particular, theories of language acquisition which posit innate domain-specific knowledge and/or processes as necessary pre-requisites are committed to the notion that the development of language and the development of thought involve importantly independent processes. It follows that adult systems of language and thought are also likely to be independent, though of course interactive, a view which is associated with a communicative conception of the relationship between language and thought. This type of theory is also consistent with the notion of a language module, both in development and in adult function. Chomsky (1980; 1995a) and Pinker (1994) are well known exponents of this type of theory. Conversely, theories which posit innate domain-general cognitive processes as the main engines of language acquisition are committed to the notion that language and thought involve shared processes in development and in adult function, a view which is more consistent with the cognitive conception of the relationship between language and thought. This type of theory is not consistent with the notion of an innate domainspecific language module operating during development. However, it is perfectly consistent with the child's gradual acquisition of a body of domain-specific linguistic knowledge and skills. The best-known current theory of this type is that proposed by Bates and MacWhinney (1987).