deep structure

A central theoretical term in TRANSFORMATIONAL GRAMMAR; opposed to SURFACE STRUCTURE. ‘Deep structure’ (or deep grammar) is the abstract SYNTACTIC REPRESENTATION of a SENTENCE – an UNDERLYING LEVEL of structural organization which specifies all the factors governing the way the sentence should be interpreted. (The basic notion has also been referred to, in various theoretical contexts, as D-STRUCTURE, UNDERLYING structure, BASE structure, REMOTE STRUCTURE and INITIAL structure.) This level provides information which enables us to distinguish between the alternative interpretations of sentences which have the same surface form (i.e. they are AMBIGUOUS), e.g. Flying planes can be dangerous, where flying planes can be related to two underlying sentences, Planes which fly . . . and To fly planes . . . It is also a way of relating sentences which have different surface forms but the same underlying MEANING, as in the relationship between ACTIVE and PASSIVE structures, e.g. The panda chased the man as opposed to The man was chased by the panda. Transformational grammars would derive one of these alternatives from the other, or perhaps both from an even more abstract (‘deeper’) underlying structure. The various grammatical relations in such sentences can then be referred to as the ‘deep SUBJECT’, ‘deep OBJECT’, etc. (contrasted with ‘surface subject’, etc.). It is also possible to compute the ‘depth’ at which a transformation operates, by referring to the number of stages in a DERIVATION before it applies, and some attempt has been made to correlate this notion with the COMPLEXITY of a sentence.

In some generative studies, the role of deep structure has been called into question, it being suggested that a separate level of underlying syntactic organization between surface structure and meaning is unnecessary and misleading. It is also possible to find the term used in the general sense of ‘underlying structural interpretation’, without commitment to a specific interpretation in terms of transformational grammar.