Knowledge of Language: Its Nature, Origin, and Use

Chomsky's central claim is that linguistics should study 'I-language'—the internal, individual, intensional knowledge of language possessed by a speaker—rather than 'E-language,' which treats language as an external, socially shared object or a collection of utterances [citation:2]. He rejects the common conception that a language is something out in the world, whether a set of sentences in a corpus or a social convention. For Chomsky, studying E-language is merely discovering patterns in data without explaining why those patterns exist or how to choose between competing descriptions [citation:2]. The proper object of linguistic theory is the mental state of the individual, and the goal is to characterize the initial state of the language faculty and how it is modified by experience.

The book elaborates the 'principles and parameters' framework introduced in Chomsky's earlier Lectures on Government and Binding (1981). Principles are universal structural features common to all human languages, forming part of the child's innate endowment; parameters are the dimensions of variation that account for differences among languages [citation:14]. A grammar results when open parameter values are fixed on the basis of linguistic data. The book also develops the I-language/E-language distinction as a fundamental conceptual clarification. Chomsky argues that the linguist's goal is to discover the form of Universal Grammar and write grammars that incorporate its principles, while the child's task is reduced to discovering which parameter values apply to the language being acquired [citation:2].

Chomsky uses 'Plato's problem' to name the puzzle of how children acquire language so quickly and effortlessly on the basis of such limited and degenerate evidence—'why do we know so much more than we have evidence for?' [citation:7][citation:13]. His answer is that the number of possible grammars the child must consider is radically reduced by an innate Universal Grammar that is part of the biological endowment [citation:2]. By contrast, 'Orwell's problem' asks why we know so much less than we might about social and political reality—how propaganda and ideological control limit understanding [citation:13]. The final chapter, 'Notes on Orwell's Problem,' makes explicit the connection between Chomsky's linguistic rationalism and his political critique, treating both as aspects of the same inquiry into human nature and its limits.

The book was praised by prominent linguists. David Lightfoot called it a 'clear introduction to current thinking on grammatical theory,' Frederick Newmeyer described it as 'the most persuasive defense of the idea that the study of linguistic structure provides insight into the human mind,' and Julius Moravcsik called it 'the best available introduction to Chomsky's current ideas on syntax made accessible to the non-specialist' [citation:7][citation:19]. However, James W. Ney, reviewing for Language Sciences, objected to Chomsky's polemical stereotyping of opponents as 'behaviorist/structuralist' and accused him of demanding that those he disagrees with remain fixed in past positions while claiming latitude for his own evolution [citation:3]. Reviewers also noted the book's uneven structure, with Chapter 3 ('Facing Plato's Problem') running 169 pages while Chapter 5 ('Notes on Orwell's Problem') is only 11 pages [citation:13].

Aspects (1965) introduced the competence/performance distinction and the Standard Theory framework with D-structure and S-structure as levels of representation. Knowledge of Language substantially revises this architecture. The D-structure/S-structure levels are replaced by the principles-and-parameters model, and the grammar is conceived as a system of universal principles with language-particular parameter settings [citation:14]. The earlier book treated Universal Grammar as a set of substantive constraints on grammars; the 1986 book presents it as the initial state of the language faculty, a biological endowment that determines the course of language acquisition. The I-language concept also sharpens the mentalism of the earlier work: where Aspects spoke of competence as tacit knowledge, Knowledge of Language explicitly identifies it with a state of the mind/brain.

A frequent misconception is that Chomsky's I-language framework denies the social dimension of language entirely. In fact, Chomsky does not claim that social interaction or communication is unimportant; he argues that they are not the proper subject matter of linguistic theory as a branch of cognitive psychology [citation:2]. Another misreading treats the principles-and-parameters model as a fully specified theory of Universal Grammar when it is better understood as a research program specifying the form any adequate theory must take. The book is also sometimes read as claiming that children learn parameter settings by explicit instruction; Chomsky's point is that parameter setting is an unconscious, automatic process triggered by primary linguistic data, not a deliberate learning procedure. Reviewers have questioned the sharp distinction between language faculty and language ability, asking whether the two can be empirically separated [citation:13].