But Chomsky does claim that in some form or other the speaker has “internalized” rules of sentence construction, that he has “tacit” or “unconscious” knowledge of grammatical rules, and that the phrase structure rules constructed by the grammarian “represent” his competence. One of the chief difficulties of Chomsky’s theory is that no clear and precise answer has ever been given to the question of exactly how the grammarian’s account of the construction of sentences is supposed to represent the speaker’s ability to speak and understand sentences, and in precisely what sense of “know” the speaker is supposed to know the rules of the grammar.
Phrase structure rules were, as I have said, already implicit in at least some of the structuralist grammars Chomsky was attacking in Syntactic Structures. One of his earliest claims was that such rules, even in a rigorous and formalized deductive model such as we have just sketched, were not adequate to account for all the syntactical facts of natural languages. The entering wedge of his attack on structuralism was the claim that phrase structure rules alone could not account for the various sorts of cases such as “I like her cooking” and “John is eager to please.”
First, within such a grammar there is no natural way to describe the ambiguities in a sentence such as “I like her cooking.” Phrase structure rules alone would provide only one derivation for this sentence; but as the sentence is syntactically ambiguous, the grammar should reflect that fact by providing several different syntactical derivations and hence several different syntactical descriptions.
Secondly, phrase structure grammars have no way to picture the differences between “John is easy to please” and “John is eager to please.” Though the sentences are syntactically different, phrase structure rules alone would give them similar phrase markers.
Thirdly, just as in the above examples surface similarities conceal underlying differences that cannot be revealed by phrase structure grammar, so surface differences also conceal underlying similarities. For example, in spite of the different word order and the addition of certain elements, the sentence “The book will be read by the boy” and the sentence “The boy will read the book” have much in common: they both mean the same thingâ€”the only difference is that one is in the passive mood and the other in the active mood. Phrase structure grammars alone give us no way to picture this similarity. They would give us two unrelated descriptions of these two sentences.
To account for such facts, Chomsky claims that in addition to phrase structure rules the grammar requires a second kind of rule, “transformational” rules, which transform phrase markers into other phrase markers by moving elements around, by adding elements, and by deleting elements. For example, by using Chomsky’s transformational rules, we can show the similarity of the passive to the active mood by showing how a phrase marker for the active mood can be converted into a phrase marker for the passive mood. Thus, instead of generating two unrelated phrase markers by phrase structure rules, we can construct a simpler grammar by showing how both the active and the passive can be derived from the same underlying phrase marker.
To account for sentences like “I like her cooking” we show that what we have is not just one phrase marker but several different underlying sentences each with a different meaning, and the phrase markers for these different sentences can all be transformed into one phrase marker for “I like her cooking.” Thus, underlying the one sentence “I like her cooking” are phrase markers for “I like what she cooks,” “I like the way she cooks,” “I like the fact that she cooks,” etc. For example, underlying the two meanings, “I like what she cooks” and “I like it that she is being cooked,” are the two phrase markers:3
Different transformational rules convert each of these into the same derived phrase marker for the sentence “I like her cooking.” Thus, the ambiguity in the sentence is represented in the grammar by phrase markers of several quite different sentences. Different phrase markers produced by the phrase structure rules are transformed into the same phrase marker by the application of the transformational rules.
Because of the introduction of transformational rules, grammars of Chomsky’s kind are often called “transformational generative grammars” or simply “transformational grammars.” Unlike phrase structure rules which apply to a single left-hand element in virtue of its shape, transformational rules apply to an element only in virtue of its position in a phrase marker: instead of rewriting one element as a string of elements, a transformational rule maps one phrase marker into another. Transformational rules therefore apply after the phrase structure rules have been applied; they operate on the output of the phrase structure rules of the grammar.
Corresponding to the phrase structure rules and the transformational rules respectively are two components to the syntax of the language, a base component and a transformational component. The base component of Chomsky’s grammar contains the phrase structure rules, and these (together with certain rules restricting which combinations of words are permissible so that we do not get nonsense sequences like “The book will read the boy”) determine the deep structure of each sentence. The transformational component converts the deep structure of the sentence into its surface structure. In the example we just considered, “The book will be boy” and the sentence “The boy will read the book,” two surface structures are derived from one deep structure. In the case of “I like her cooking,” one surface structure is derived from several different deep structures.
At the time of the publication of Aspects of the Theory of Syntax it seemed that all of the semantically relevant parts of the sentence, all the things that determine its meaning, were contained in the deep structure of the sentence. The examples we mentioned above fit in nicely with this view. “I like her cooking” has different meanings because it has different deep structures though only one surface structure; “The boy will read the book” and “The book will be read by the boy” have different surface structures, but one and the same deep structure, hence they have the same meaning.
This produced a rather elegant theory of the relation of syntax to semantics and phonology: the two components of the syntax, the base component and the transformational component, generate deep structures and surface structures respectively. Deep structures are the input to the semantic component, which describes their meaning. Surface structures are the input to the phonological component, which describes their sound. In short, deep structure determines meaning, surface structure determines sound. Graphically the theory of a language was supposed to look like this:
The task of the grammarian is to state the rules that are in each of the little boxes. These rules are supposed to represent the speaker’s competence. In knowing how to produce and understand sentences, the speaker, in some sense, is supposed to know or to have “internalized” or have an “internal representation of” these rules.
The elegance of this picture has been marred in recent years, partly by Chomsky himself, who now concedes that surface structures determine at least part of meaning, and more radically by the younger Turks, the generative semanticists, who insist that there is no boundary between syntax and semantics and hence no such entities as syntactic deep structures.
Seen as an attack on the methods and assumptions of structural linguistics, Chomsky’s revolution appears to many of his students to be not quite revolutionary enough. Chomsky inherits and maintains from his structuralist upbringing the conviction that syntax can and should be studied independently of semantics; that form is to be characterized independently of meaning. As early as Syntactic Structures he was arguing that “investigation of such [semantic] proposals invariably leads to the conclusion that only a purely formal basis can provide a firm and productive foundation for the construction of grammatical theory.”4
The structuralists feared the intrusion of semantics into syntax because meaning seemed too vaporous and unscientific a notion for use in a rigorous science of language. Some of this attitude appears to survive in Chomsky’s persistent preference for syntactical over semantic explanations of linguistic phenomena. But, I believe, the desire to keep syntax autonomous springs from a more profound philosophical commitment: man, for Chomsky, is essentially a syntactical animal. The structure of his brain determines the structure of his syntax, and for this reason the study of syntax is one of the keys, perhaps the most important key, to the study of the human mind.
It is of course true, Chomsky would say, that men use their syntactical objects for semantic purposes (that is, they talk with their sentences), but the semantic purposes do not determine the form of the syntax or even influence it in any significant way. It is because form is only incidentally related to function that the study of language as a formal system is such a marvelous way of studying the human mind.
It is important to emphasize how peculiar and eccentric Chomsky’s overall approach to language is. Most sympathetic commentators have been so dazzled by the results in syntax that they have not noted how much of the theory runs counter to quite ordinary, plausible, and common-sense assumptions about language. The commonsense picture of human language runs something like this. The purpose of language is communication in much the same sense that the purpose of the heart is to pump blood. In both cases it is possible to study the structure independently of function but pointless and perverse to do so, since structure and function so obviously interact. We communicate primarily with other people, but also with ourselves, as when we talk or think in words to ourselves. Human languages are among several systems of human communication (some others are gestures, symbol systems, and representational art) but language has immeasurably greater communicative power than the others.
We don’t know how language evolved in human prehistory, but it is quite reasonable to suppose that the needs of communication influenced the structure. For example, transformational rules facilitate economy and so have survival value: we don’t have to say, “I like it that she cooks in a certain way,” we can say, simply, “I like her cooking.” We pay a small price for such economies in having ambiguities, but it does not hamper communication much to have ambiguous sentences because when people actually talk the context usually sorts out the ambiguities. Transformations also facilitate communication by enabling us to emphasize certain things at the expense of others: we can say not only “Bill loves Sally” but also “It is Bill that loves Sally” and “It is Sally that Bill loves.” In general an understanding of syntactical facts requires an understanding of their function in communication since communication is what language is all about.