2. Deep Structure and Surface Structure

 
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.