Michael Tomasello 
Constructing a Language [PDF ebook] 
A Usage-Based Theory of Language Acquisition

In this groundbreaking book, Michael Tomasello presents a comprehensive usage-based theory of language acquisition. Drawing together a vast body of empirical research in cognitive science, linguistics, and developmental psychology, Tomasello demonstrates that we don’t need a self-contained “language instinct” to explain how children learn language. Their linguistic ability is interwoven with other cognitive abilities.
Tomasello argues that the essence of language is its symbolic dimension, which rests on the uniquely human ability to comprehend intention. Grammar emerges as the speakers of a language create linguistic constructions out of recurring sequences of symbols; children pick up these patterns in the buzz of words they hear around them.
All theories of language acquisition assume these fundamental skills of intention-reading and pattern-finding. Some formal linguistic theories posit a second set of acquisition processes to connect somehow with an innate universal grammar. But these extra processes, Tomasello argues, are completely unnecessary—important to save a theory but not to explain the phenomenon.
For all its empirical weaknesses, Chomskian generative grammar has ruled the linguistic world for forty years. Constructing a Language offers a compellingly argued, psychologically sound new vision for the study of language acquisition.