David Lightfoot writes mainly on syntactic theory, language acquisition, and historical change, which he views as intimately related. He argues that internal language change is contingent and fluky, takes place in a sequence of bursts, and is best viewed as the cumulative effect of changes in individual grammars, where a grammar is a "language organ" represented in a person's mind/brain and embodying his/her language faculty. That, in turn, entails a non-standard, discovery approach to language acquisition, which he treats as "cue-based," which enables us to understand how a language like English may develop so many idiosyncratic properties. He has published eleven books, most recently The Development of Language (Blackwell, 1999), The Language Organ (with S.R. Anderson) (Cambridge UP, 2002), and How New Languages Emerge (Cambridge UP, 2006). In 2004, he was elected a fellow of the American Association for the Advancement of Science, and in 2006, as a fellow of the Linguistic Society of America. He has been elected as President of the Linguistic Society of America, serving 2010-2011.
Lightfoot has held regular appointments at several universities including McGill, where he taught many undergraduates who went on to become major figures in linguistics and psychology; the University of Utrecht in the Netherlands; and the University of Maryland, where he established and chaired for 12 years, a new department of linguistics with a unique focus--viewing linguistics as the study of the human language organ. He was also the associate director of the neuroscience and cognitive sciences program there. In 2001, he moved to Georgetown University as dean of the graduate school. From 2005 to 2009 he served as Assistant Director of the National Science Foundation, heading the Directorate for Social, Behavioral and Economic Sciences. In 2009 he returned to Georgetown, where he is Professor of Linguistics, directs the graduate program in Communication, Culture & Technology, and co-directs (with Elissa Newport) the new Interdisciplinary PhD Concentration in Cognitive Science.