key Concepts in TGG

Chomsky, rejecting the formal analysis of sentences, distinguishes two levels of syntactic struucture in a sentence: the surface structure and the deep structure.

The surface structure (SS) is the syntactic structure of the sentence which a person speaks or hears: it is the observable form of the sentence. Chomsky argues that any analysis based on the surface structure encounters difficulties. Therefore, another level of sentence structure should be taken into account. The deep structure (DS) is much more abstract and is considered to be in the speaker's mind. It refers to certain important generalisations about the structure of the sentence which are different from its surface. The deep structure contains all the syntactic information needed for the understanding of a given sentence. The deep structure is converted into a surface structure after the application of a specific kind of rules called transformational rules (TRs). 

                                                      DS--------------- TRs----------------------- SS

Examples

• John is eager to please. (I)
•  John is easy to please. (II)

In the deep structures of these two sentences, it is clear that “John” is either the subject of pleasing or its object.
This distinction between surface and deep syntax became a major dichotomy in TGG, and, for many people, it is the main difference between the old and new approaches to syntax. For Chomsky, grammar is not confined to formal description but it should incorporate the internal processes that take place in the speaker's mind.

According to Chomsky, language is creative and behaviourism is totally unable to explain creativity. He argues that the comparison of the sentences a speaker has heard (the input) with the sentences a speaker produces (the output) shows differences between them. That is to say, the output contains sentences the speaker has never heard before. On the basis of this evidence, one can deduce that there is “something” between the input and the output. Chomsky calls it the Language Acquisition Device (LAD)

Input ----------------- LAD -------------------- output

The LAD is an inborn capacity (a genetic mechanism or apparatus) which is present in the brain right from the beginning and which enables children (by the age of 3 to 4) to extract the rules of language from speech when they are exposed to it and to use them productively. Animals do not possess this capacity. For this reason, their learning of language-like behaviour stops at a definite stage even if they are exposed to it. 

Language acquisition takes place not as a result of imitation (stimulus + response) but as a result of the functioning of the LAD. In fact, what happens is that the child, when exposed to adult language, tries mentally to form hypotheses about its rules, then he tests the validity of these rules continuously and adapts them until he internally masters the abstract system of rules that adults have as part of their competence. So, language acquisition is part of the maturational process.

This view about language learning is called mentalism. It is based on the premise that human beings possess minds.