In the study of Transformational Generative Grammar, what are deep structure and surface structure?
In Noam Chomsky's Transformational Generative Grammar, the surface structure of a sentence is the the grammatical construction. For instance, examine the two sentences:
- The calved Greenland ice shelf may cause sea levels to rise to unexpected levels.
- The threatened shores of New York may cause government to rise to the alarm of warming oceans.
Their grammatical structure is similar. Each has a noun phrase filling the Subject slot with "may cause" in the Verb slot, with a noun in the Object slot modified by a to-infinitive phrase. When considering surface structure, these sentences are comparable.
Deep structure has to do with the meaning of the structurally similar component to rise. In the first sentence, to rise is an infinitive verb indicating a natural physical action that may occurred, while in the second sentence, to rise has an idiomatic and figurative sense meaning government may summon up the moral fortitude to do what is necessitated by the threat of warming seas. When considering deep structure, these sentences are separated by the difference between a fact (a natural physical action) and a figure of speech that is not literal and is tied to agreed upon cultural ideas in order to convey meaning.