||In the field of linguistics, there has been a huge upsurge of interest in syntactic theory in the latter half of this century, largely due to the dominating influence of Noam Chomsky. Almost every major recent innovation in syntactic theory has either originated with Chomsky or in reaction to particular ideas of his. There are, though, numerous competing theories of syntax, whose diversity is matched only by their volatility. Indeed, Chomsky\'s own thinking has resulted in three quite distinct phases, each of which has marked a dramatic reappraisal of the goals of syntactic theory.
The earliest version of Chomsky\'s theory is notable for an interest in the mathematical properties of human languages, in particular the capacity for a finite set of grammatical rules to generate an infinite number of different sentences. An important conclusion from this period was that phrase structure (PS) rules, which specify how words can combine into sentences, cannot by themselves deal with certain kinds of syntactic phenomena. The shortcomings of PS rules were initially compensated for by so-called transformational rules, which dealt with the necessary movement of elements within sentences, in addition to describing how certain sentence types are related (for instance, active and passive; declarative and interrogative). Several other theories which have risen to prominence in the 1980s, including Lexical Functional Grammar (LFG) and Generalized Phrase Structure Grammar (GPSG), also commonly acknowledge that PS rules need to be modified in some way.
The latest version of Chomsky\'s theory (now often referred to as universal grammar or UG), has restricted the role of transformations enormously. The constraint of transformational rules has been carried to its logical conclusion within GPSG, since transformational rules have been abolished altogether. Instead, the phrase structure of a sentence permits the flow of information from one part of the sentence to another, in a tightly constrained manner. LFG has also abandoned transformational rules, and relies instead on the properties of lexical items to explain the connections between sentence types. For example, the relationship between active and passive sentences is established via the lexical properties of active and passive verb forms (for example, eat/is eaten; see/was seen).
While the interest in mathematical formalism has diminished within UG, it has been applied even more rigorously within GPSG. However, GPSG disputes Chomsky\'s early belief in the autonomy of syntax and instead explores the links between the structural form of a sentence and the meanings conveyed thereby. LFG, on the other hand, shares Chomsky\'s interest in the psychological reality of syntactic theory. On this view, a syntactic theory is adequate only if it describes the language system that a native speaker actually has in his or her mind. LFG is notable for asserting that grammatical functions, such as subject and object, are of primary importance.
Despite many fundamental differences between competing syntactic theories, there are many common assumptions. For example, a significant shift in emphasis is emerging, which asserts that the meanings of individual words determine to a large extent what kinds of sentence structures they can occur in. With this shift towards lexical determination of sentence structure, the role of purely syntactic phenomena in determining grammaticality may prove ultimately to be quite limited. MS
See also generative grammar; transformational grammar.Further reading P. Sells, Lectures on Contemporary Syntactic Theories.