Deep structure
The original idea of Noam Chomsky's Deep Structure was that multiple "surface forms" are often derive from a single underlying form. The classic example was the passive construction; e.g., "John loves Mary" is clearly related to "Mary is loved by John". The "surface structures" of these two sentences were said to be derived from the same deep structure (roughly corresponding to "John loves Mary") by "transformations", which is why the theory came to be called "transformational grammar". It should be noted that transformations do not, strictly speaking, operate on sentences, but on abstract structures known as phrase markers (these are often represented as tree diagrams). It is tempting to regard Deep Structures as representing meanings, and Surface structures as representing sentences expressing those meanings, but this is not the theory as described by Chomsky. A sentence in the normal sense of the word more closely corresponds to a deep structure paired with the surface structure derived from it, with an additional phonetic structure obtained from processing of the surface structure. In the traditional theory, sentences with identical deep structures have to have identical meanings, but the reverse is not true: sentences with identical meanings may (and often do) have different deep stuctures.Unfortunately, the "surface" appeal of the Deep Structure concept soon led people from unrelated fields (architecture, music, politics) to misuse and abuse the term to express various things in their own work, which rarely if ever had the rigor of Chomsky's own linguistic scholarship. Perhaps it was this situation that led Chomsky and his students to abandon the term entirely, replacing it with the abbreviation "DS".
In 1980 and 1981, Chomsky's theory took a new turn, becoming known as Government and Binding Theory (the name is somewhat misleading, since Government and Binding are not the only significant components of the theory). In his book Barriers, Chomsky attempted to unify various (technical) concepts in GB theory which had previously been separate. In 1993 he published an extremely significant paper, A Minimalist Program for Linguistic Theory (not to be confused with the 1995 book The Minimalist Program containing the paper along with other writings), which proposed the use of economy conditions in syntax to a greater extent than had previously been considered.
Current Chomskyan linguistics no longer makes use of the term "deep structure", though this is for purely techincal reasons. Hence, one way to make yourself look pretentious, misinformed, and tragically unhip to a group of linguists is to say something about the "Deep Structure" of the mind, supposedly revealed by Chomsky. To be fair, this is more a matter of nomenclature than anything else, as the most robust (and controversial) notion put forth by Chomsky has been the concept of a "Universal Grammar" that constrains the overall forms of linguistic expression available to the human species. This concept -- more of a grammar-schema than a grammar -- is probably what non-linguists are referring to when they say "Deep Structure". This usage seems quite natural and appropriate, but it is liable to cause unnecessary confusion.
References
It is in early works such as these that the original concept of the deep structure/surface structure distinction is presented. For an account of more current ideas in transformational grammar, see
- Chomsky, N. Barriers (Linguistic Inquiry Monographs) (1986) MIT Press.
- Chomsky, N. The Minimalist Program. (1995) MIT Press.