Diachronic Syntax and Generative Grammar

1. The problem . The objectives of diachronic linguistics have always been to reconstruct the particular steps by which a language changes, and also to hypothesize about processes of language change in general. Recent discussion of the latter problem has frequently involved five closely related proposals. First, language changes by means of a series of individual innovations. These innovations consist primarily in the addition of single rules to the grammar of the adult speaker. Second, these innovations usually occur at some point of break in a grammar; for example, ‘before the first morphophonemic rule involving immediate constituent structure of the utterance … before the phonological rules that eliminate boundary markers from the representation’. Third, these innovations are passed on to the next generation when the child imitates the adult. A child may internalize the adult's grammar; or, more probably, he will simplify it. This is because children have an ability, not shared by most adults, to construct by induction from the utterances to which they have been exposed, the simplest grammar capable of generating sentences. The simplification will give rise to a discontinuity in transmission from generation to generation. In the interests of preserving intelligibility, this discontinuity will be minimal. Fourth, whenever the discontinuity results in radical changes such as restructuring, a mutation occurs. Finally, these mutations, which affect the overall simplicity of the grammar, are rare.