How and why do languages change over time? Could the way an individual child develops affect aggregate language change? What do the mechanisms of change tell us about the evolution of language in our species? To answer these questions, David Lightfoot looks closely at young children. A child develops a grammar on exposure to some triggering experience. A small perturbation in the trigger may entail a different grammar in the next population of speakers, with dramatic effects. This sensitive dependence on initial conditions is the key to explaining how languages change, and why they change in fits and starts. The cue-based approach to language acquisition presented here is a radical departure from formal models of language learning. Lightfoot challenges conventional understanding by showing that language change is essentially contingent - unpredictable but explainable; and he contests how far natural selection enables us to understand the evolution of the language faculty in the species.

David Lightfoot is Professor of Linguistics at the University of Maryland, College Park where he is also Associate Director of the program in Neural and Cognitive Science. His books include The Language Lottery and How to Set Parameters.