The revolution in linguistic thought associated with the name of Professor Noam Chomsky centres on the theory of transformational generation, especially in grammar. This book subjects the main theory and some of its applications to a searching critique. It finds the theory in some places circular, in general descriptively inadequate, but above all aprioristic and dangerously unempirical. Professor Derwing writes as a linguist particularly interested in the psychology of language acquisition, and conscious that the TGG model starts from assumptions about the mind and linguistic universals which dictate the form and the consequences of the argument. They strike Professor Derwing as arbitrary and merely formal, and as contradicting basic scientific mental habits. In brief, Professor Derwing disputes that TGG exemplifies proper empirical scientific inquiry; that something like a TGG is part of the output of normal language acquisition; or that TGG provides a valid heuristic for psychological investigation. He argues therefore for a more experimental approach if we are actually to discover how language is acquired.