The chapters in Part I of this book all focus on issues concerning the emergence of language and cognition during child development, and concerning the evolution of linguistic capacities and distinctive human intelligence in our hominid past. Following some general introductory remarks on the way in which these issues are relevant to the debate over the relationship between language and thought, we will provide some brief background discussion for each of the four chapters.

Any position one might adopt on the question of the relationship between language and thought will carry commitments, of one sort or another, concerning the structure and organisation of mature human cognition. And that, in turn, may have implications for the kind of developmental story which it is possible to tell. Moreover, whatever account is given of mature human cognition had better permit some plausible account to be provided of the evolutionary origins of the latter. For example, suppose one held that language is the vehicle for certain kinds of thought; say all propositional thought – hence being committed to the cognitive conception of language in quite a strong form. In that case one had better maintain that language-acquisition is a necessary condition for young children to engage in propositional thinking; and that those children who are deprived of, or delayed in the acquisition of, language will be incapable of entertaining just these kinds of thought. Similarly, one had better be prepared to give an account of human evolution such that no capacities for propositional thought were present prior to the evolution of linguistic ability (e.g. Bickerton, 1990, 1995).