The two basic approaches to linguistics are the formalist and the functionalist approaches. In this engaging monograph, Frederick J. Newmeyer, a formalist, argues that both approaches are valid. However, because formal and functional linguists have avoided direct confrontation, they remain unaware of the compatability of their results. One of the author's goals is to make each side accessible to the other. While remaining an ardent formalist, Newmeyer stresses the limitations of a narrow formalist outlook that refuses to consider that anything of interest might have been discovered in the course of functionalist-oriented research. He argues that the basic principles of generative grammar, in interaction with principles in other linguistic domains, provide compelling accounts of phenomena that functionalists have used to try to refute the generative approach.
Newmeyer discusses the gap between formalists and functionalists in this book. Each school of thinking suffers from some inherent limitations, but both aim at one goal, adequate explanation of language.
As for now, this book is over my head and well beyond my knowledge of linguistics. However, with more knowledge under belt, I can see this would be a good book to own, particularly in the way it explains the positions of functionalist and generative linguists and argues in support of and against their claims.