This book combines ideas about the architecture of grammar and language acquisition, processing, and change to explain why languages show regular patterns when there is so much irregularity in their use and so much complexity when there is such regularity in linguistic phenomena. Peter Culicover argues that the structure of language can be understood and explained in terms of two kinds of complexity: firstly that of the correspondence between form and meaning; secondly in the real-time processes involved in the construction of meanings in linguistic expressions.