Following Syntactic Structures, Chomsky’s next books, Current Issues in Linguistic Theory (1964) and Aspects of the Theory of Syntax (1965), continued to develop and refine his theories of transformational syntax. With Cartesian Linguistics: A Chapter in the History of Rationalist Thought (1966), he began to explore more fully the psychological implications of his work, emphasizing the “mentalist,” or antiempirical, nature of language. Language and Mind (1968), often called his most comprehensible book for beginning students of his work, summarizes the preceding publications and suggests the need for additional study of semantics. Also in that work—specifically, in the chapter “Linguistics Contributions: Future”—he predicts the direction of forthcoming research along the lines of abstract mathematical processes, analogies with mental processes involved in space perception, the search for a universal grammar, and psychological and biological studies of the brain’s functions. His work was expanding the implications of linguistics into areas of philosophy, psychology, and the sciences. Subsequent books—including Studies on Semantics in Generative Grammar (1972), The Logical Structure of Linguistic Theory (1975), Rules and Representations (1980), and Lectures on Government and Binding (1981)—addressed mathematical processes and the search for a universal grammar. It is primarily the theses work of these works and the critical responses to them which Chomsky recapitulates in the four chapters on “Plato’s problem” in Knowledge of Language.
In following the lines of semantic research, Chomsky became increasingly interested in the pragmatic use of semantics in politics and government. This interest led to several books in the 1970’s on political and military semantics and finally to participation in the anti-Vietnam War movement and critiques of political policy. Chomsky’s interest in political semantics is only mentioned in Knowledge of Language, in his treatment of “Orwell’s problem” in chapter 5.
By the time of writing Knowledge of Language, Chomsky’s adoption of semantic research by fellow linguists and his progress in semantics in his own theories had answered the early criticisms that his work was too limited to syntactic considerations. It was his mentalist philosophy that continued to provoke the criticism that he addresses in Knowledge of Language. This book’s importance rests on Chomsky’s summary of his later theories about semantics and universal grammar and on his rationale for the mentalistic interpretation of knowledge.