David Lightfoot,The development of language: acquisition, change, and evolution. (Maryland Lectures in Language and Cognition 1.) Malden, MA & Oxford: Blackwell, 1999. Pp. xii+287.

The central thesis of The development of language is that there are no principles of grammatical change, so that ‘historicist’ or deterministic approaches to diachronic change are misguided. Instead, Lightfoot argues that language change can only be understood by taking the perspective of the ‘growth’ (i.e. acquisition) of an individual's biological grammar, which may end up with a different parameter setting from the parent's generation when the trigger experience changes. Such events of grammatical change are abrupt and unpredictable, and Lightfoot suggests that they can be understood better from the point of view of catastrophe theory and chaos theory than under a deterministic theory of history as was common in the nineteenth century.