Transformational grammar

Transformational grammar is a broad term describing grammars (almost exclusively those of natural languages) that have been developed in a Chomskyan tradition.

Deep structure and surface structure

In the early to mid 1960s, Noam Chomsky developed the idea that each sentence in a language has two levels of representation - a deep structure and a surface structure. The deep structure was (more-or-less) a direct representation of the basic semantic relations underlying a sentence, and was mapped onto the surface structure (which followed the phonological form of the sentence very closely) via transformations. Chomsky believed that there would be considerable similarities between the Deep Structures of different languages, and that these structures would reveal properties, common to all languages, which were concealed by their Surface Structures. However, this was perhaps not the central motivation for introducing Deep Structure. Transformations themselves had been proposed prior to the development of Deep Structure, essentially as a means of increasing the mathematical and descriptive power of Context free grammars. Similarly, Deep Structure was devised largely for narrow technical reasons relating to early semantic theory. Chomsky emphasizes the importance of modern formal mathematical devices in the development of grammatical theory:

But the fundamental reason for the inadequacy of traditional grammars is a more technical one. Although it was well understood that linguistic processes are in some sense "creative", the technical devices for expressing a system of recursive processes were simply not available until much more recently.

Innate linguistic knowledge

Terms such as "transformation" can give the impression that theories of transformational generative grammar are intended as a model for the processes through which the human mind constructs and understands sentences. Chomsky is clear that this is not in fact the case: a generative grammar models only the knowledge that underlies the human ability to speak and understand. One of the most important of Chomsky's ideas is that most of this knowledge is innate, with the result that a baby can have a large body of prior knowledge about the structure of language in general, and need only actually learn the idiosyncratic features of the language(s) it is exposed to. Chomsky was not the first person to suggest that all languages had certain fundamental things in common (he quotes philosophers writing several centuries ago who had the same basic idea), but he helped to make the innateness theory respectable after a period dominated by more behaviorist attitudes towards language. Perhaps more significantly, he made concrete and technically sophisticated proposals about the structure of language, and made important proposals regarding how the success of grammatical theories should be evaluated.

Chomsky goes so far as to suggest that a baby need not learn any actual rules specific to a particular language at all. Rather, all languages are presumed to follow the same set of rules, but the effects of these rules and the interactions between them can vary greatly depending on the values of certain universal linguistic parameters. This is often referred to as the principles and parameters framework. It is a very strong assumption, and is one of the more subtle ways in which Chomsky's current theory of language differs from most others.

Grammatical theories

In the 1960s, Chomsky introduced two central ideas relevant to the construction and evaluation of grammatical theories. The first was the distinction between competence and performance. Chomsky noted the obvious fact that people, when speaking in the real world, often make linguistic errors (e.g. starting a sentence and then abandoning it midway through). He argued that these errors in linguistic performance were irrelevant to the study of linguistic competence (the knowledge that allows people to construct and understand grammatical sentences). Consequently, the linguist can study an idealised version of language, greatly simplifying linguistic analysis (see the "Grammaticalness" section below). The second idea related directly to the evaluation of theories of grammar. Chomsky made a distinction between grammars that achieved descriptive adequacy and those that went further and achieved explanatory adequacy. A descriptively adequate grammar for a particular language defines the (infinite) set of grammatical sentences in that language; that is, it describes the language in its entirety. A grammar that achieves explanatory adequacy has the additional property that it gives an insight into the underlying linguistic structures in the human mind; that is, it does not merely describe the grammar of a language, but makes predictions about how linguistic knowledge is mentally represented. For Chomsky, the nature of such mental representations is largely innate, so if a grammatical theory has explanatory adequacy it must be able to explain the various grammatical nuances of the languages of the world as relatively minor variations in the universal pattern of human language. Chomsky argued that, even though linguists were still a long way from constructing descriptively adequate grammars, progress in terms of descriptive adequacy would only come if linguists held explanatory adequacy as their goal. In other words, real insight into the structure of individual languages could only be gained through the comparative study of a wide range of languages, on the assumption that they are all cut from the same cloth.

de:Generative Transformationsgrammatik es:Gramática transformacional fa:دستور گشتاری ia:Grammatica transformational-generative ja:生成文法 pt:Gramática transformacional zh:转换-生成语法