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A Special Supplement: Chomsky’s Revolution in Linguistics

Such “syntactically ambiguous” sentences form a crucial test case for any theory of syntax. The examples are ordinary pedestrian English sentences, there is nothing fancy about them. But it is not easy to see how to account for them. The meaning of any sentence is determined by the meanings of the component words (or morphemes) and their syntactical arrangement. How then can we account for these cases where one sentence containing unambiguous words (and morphemes) has several different meanings? Structuralist linguists had little or nothing to say about these cases; they simply ignored them. Chomsky was eventually led to claim that these sentences have several different syntactical structures, that the uniform surface structure of, e.g., “I like her cooking” conceals several different underlying structures which he called “deep” structures. The introduction of the notion of the deep structure of sentences, not always visible in the surface structure, is a crucial element of the Chomsky revolution, and I shall explain it in more detail later.

One of the merits of Chomsky’s work has been that he has persistently tried to call attention to the puzzling character of facts that are so familiar that we all tend to take them for granted as not requiring explanation. Just as physics begins in wonder at such obvious facts as that apples fall to the ground or genetics in wonder that plants and animals reproduce themselves, so the study of the structure of language beings in wondering at such humdrum facts as that “I like her cooking” has different meanings, “John is eager to please” isn’t quite the same in structure as “John is easy to please,” and the equally obvious but often overlooked facts that we continually find ourselves saying and hearing things we have never said or heard before and that the number of possible new sentences is infinite.

The inability of structuralist methods to account for such syntactical facts eventually led Chomsky to challenge not only the methods but the goals and indeed the definition of the subject matter of linguistics given by the structuralist linguists. Instead of a taxonomic goal of classifying elements by performing sets of operations on a corpus of utterances, Chomsky argued that the goal of linguistic description should be to construct a theory that would account for the infinite number of sentences of a natural language. Such a theory would show which strings of words were sentences and which were not, and would provide a description of the grammatical structure of each sentence.

Such descriptions would have to be able to account for such facts as the internal grammatical relations and the ambiguities described above. The description of a natural language would be a formal deductive theory which would contain a set of grammatical rules that could generate the infinite set of sentences of the language, would not generate anything that was not a sentence, and would provide a description of the grammatical structure of each sentence. Such a theory came to be called a “generative grammar” because of its aim of constructing a device that would generate all and only the sentences of a language.

This conception of the goal of linguistics then altered the conception of the methods and the subject matter. Chomsky argued that since any language contains an infinite number of sentences, any “corpus,” even if it contained as many sentences as there are in all the books of the Library of Congress, would still be trivially small. Instead of the appropriate subject matter of linguistics being a randomly or arbitrarily selected set of sentences, the proper object of study was the speaker’s underlying knowledge of the language, his “linguistic competence” that enables him to produce and understand sentences he has never heard before.

Once the conception of the “corpus” as the subject matter is rejected, then the notion of mechanical procedures for discovering linguistic truths goes as well. Chomsky argues that no science has a mechanical procedure for discovering the truth anyway. Rather, what happens is that the scientist formulates hypotheses and tests them against evidence. Linguistics is no different: the linguist makes conjectures about linguistic facts and tests them against the evidence provided by native speakers of the language. He has in short a procedure for evaluating rival hypotheses, but no procedure for discovering true theories by mechanically processing evidence.

The Chomsky revolution can be summarized in the following chart:


Most of this revolution was already presented in Chomsky’s book Syntactic Structures. As one linguist remarked, “The extraordinary and traumatic impact of the publication of Syntactic Structures by Noam Chomsky in 1957 can hardly be appreciated by one who did not live through this upheaval.”2 In the years after 1957 the spread of the revolution was made more rapid and more traumatic by certain special features of the organization of linguistics as a discipline in the United States. Only a few universities had separate departments of linguistics. The discipline was (by contrast to, say, philosophy or psychology), and still is, a rather cozy one. Practitioners were few; they all tended to know one another; they read the same very limited number of journals; they had, and indeed still have, an annual get-together at the Summer Linguistics Institute of the Linguistic Society of America, where issues are thrashed out and family squabbles are aired in public meetings.

All of this facilitated a rapid dissemination of new ideas and a dramatic and visible clash of conflicting views. Chomsky did not convince the established leaders of the field but he did something more important, he convinced their graduate students. And he attracted some fiery disciples, notably Robert Lees and Paul Postal.

The spread of Chomsky’s revolution, like the spread of analytic philosophy during the same period, was a striking example of the Young Turk phenomenon in American academic life. The graduate students became generative grammarians even in departments that had traditionalist faculties. All of this also engendered a good deal of passion and animosity, much of which still survives. Many of the older generation still cling resentfully to the great traditions, regarding Chomsky and his “epigones” as philistines and vulgarians. Meanwhile Chomsky’s views have become the conventional wisdom, and as Chomsky and his disciples of the Sixties very quickly become Old Turks a new generation of Young Turks (many of them among Chomsky’s best students) arise and challenge Chomsky’s views with a new theory of “generative semantics.”


The aim of the linguistic theory expounded by Chomsky in Syntactic Structures (1957) was essentially to describe syntax, that is, to specify the grammatical rules underlying the construction of sentences. In Chomsky’s mature theory, as expounded in Aspects of the Theory of Syntax (1965), the aims become more ambitious: to explain all of the linguistic relationships between the sound system and the meaning system of the language. To achieve this, the complete “grammar” of a language, in Chomsky’s technical sense of the word, must have three parts, a syntactical component that generates and describes the internal structure of the infinite number of sentences of the language, a phonological component that describes the sound structure of the sentences generated by the syntactical component, and a semantic component that describes the meaning structure of the sentences. The heart of the grammar is the syntax; the phonology and the semantics are purely “interpretative,” in the sense that they describe the sound and the meaning of the sentences produced by the syntax but do not generate any sentences themselves.

The first task of Chomsky’s syntax is to account for the speaker’s understanding of the internal structure of sentences. Sentences are not unordered strings of words, rather the words and morphemes are grouped into functional constituents such as the subject of the sentence, the predicate, the direct object, and so on. Chomsky and other grammarians can represent much, though not all, of the speaker’s knowledge of the internal structure of sentences with rules called “phrase structure” rules.

The rules themselves are simple enough to understand. For example, the fact that a sentence (S) can consist of a noun phrase (NP) followed by a verb phrase (VP) we can represent in a rule of the form: S → NP + VP. And for purposes of constructing a grammatical theory which will generate and describe the structure of sentences, we can read the arrow as an instruction to rewrite the left-hand symbol as the string of symbols on the right-hand side. The rewrite rules tell us that the initial symbol S can be replaced by NP + VP. Other rules will similarly unpack NP and VP into their constituents. Thus, in a very simple grammar, a noun phrase might consist of an article (Art) followed by a noun (N); and a verb phrase might consist of an auxiliary verb (Aux), a main verb (V), and a noun phrase (NP). A very simple grammar of a fragment of English, then, might look like this:

  1. S → NP + VP

  2. NP → Art + N

  3. VP → Aux + V + NP

  4. Aux → (can, may, will, must, etc.)

  5. V → (read, hit, eat, etc.)

  6. Art → (a, the)

  7. N → (boy, man, book, etc.)

If we introduce the initial symbol S into this system, then construing each arrow as the instruction to rewrite the left-hand symbol with the elements on the right (and where the elements are bracketed, to rewrite it as one of the elements), we can construct derivations of English sentences. If we keep applying the rules to generate strings until we have no elements in our strings that occur on the left-hand side of a rewrite rule, we have arrived at a “terminal string.” For example, starting with S and rewriting according to the rules mentioned above, we might construct the following simple derivation of the terminal string underlying the sentence “The boy will read the book”:


NP + VP (by rule 1)

Art + N + VP (by rule 2)

Art + N + Aux + V + NP (by rule 3)

Art + N + Aux + V + Art + N

(by rule 2)

the + boy + will + read + the + book

(by rules 4, 5, 6, and 7)

The information contained in this derivation can be represented graphically in a tree diagram of the following form:


This “phrase marker” is Chomsky’s representation of the syntax of the sentence “The boy will read the book.” It provides a description of the syntactical structure of the sentence. Phrase structure rules of the sort I have used to construct the derivation were implicit in at least some of the structuralist grammars; but Chomsky was the first to render them explicit and to show their role in the derivations of sentences. He is not, of course, claiming that a speaker actually goes consciously or unconsciously through any such process of applying rules of the form “rewrite X as Y” to construct sentences. To construe the grammarian’s description this way would be to confuse an account of competence with a theory of performance.

  1. 2

    Howard Maclay, “Overview,” in D. Steinberg and L. Jacobovitz, eds., Semantics (Cambridge University Press, 1971), p. 163.

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