Transformational-Generative Grammar

In the 1950s the school of linguistic thought known as transformational-generative grammar received wide acclaim through the works of Noam Chomsky. Chomsky postulated a syntactic base of language (called deep structure), which consists of a series of phrase-structure rewrite rules, i.e., a series of (possibly universal) rules that generates the underlying phrase-structure of a sentence, and a series of rules (called transformations) that act upon the phrase-structure to form more complex sentences. The end result of a transformational-generative grammar is a surface structure that, after the addition of words and pronunciations, is identical to an actual sentence of a language. All languages have the same deep structure, but they differ from each other in surface structure because of the application of different rules for transformations, pronunciation, and word insertion. Another important distinction made in transformational-generative grammar is the difference between language competence (the subconscious control of a linguistic system) and language performance (the speaker's actual use of language). Although the first work done in transformational-generative grammar was syntactic, later studies have applied the theory to the phonological and semantic components of language.

CREATIVITY/ PRODUCTIVITY
The productivity of language means that there is no limit to the complexity of structure of or number of English sentences that we use and understand. We can add phrases for new animals to 'The old lady swallowed a cat that swallowed a mouse that swallowed a spider that swallowed a fly' without limit, each time creating a more complex structure. So there is no way to explain competence by listing a finite number of English sentence forms.
According to some cognitive scientists and philosophers, productivity is also a feature of human thought. One way of arguing for the extension of this feature to thought is to argue that thought shares the properties of natural languages that enables language to be indefinitely productive.

A Noun Phrase

A word or sequence of words consisting of a noun or a noun plus one or more modifiers. For example, 'cat', 'the cat', 'the black cat' are all noun phrases. In the sentence, 'The black cat is happy,' 'the black cat' is the noun phrase; 'the black cat is' is not a noun phrase. Noun phrases can be constructed recursively. That is, a noun phrase can contain another phrase within it (such as a verb phrase or another noun phrase), that contains within it another phrase, and so on. The noun phrase is one type of phrase among others in contemporary theories of grammar.
A PHRASE STRUCTURE TREE
A phrase structure tree is a form of representation of sentences in which nodes or elements are labelled by syntactic category (noun phrase (NP), verb phrase (VP), prepositional phrase (PP), etc.)


STRUCTURE/ SURFACE - DEEP

The transformational grammar was a theory of how grammatical knowledge is represented and processed in the brain. Developed by Noam Chomsky in the1960's, the transformational grammar consisted of:
1. Two levels of representation of the structure of sentences: an underlying, more abstract form, termed 'deep structure', and the actual form of the sentence produced, called 'surface structure'. Deep structure is represented in the form of a heirarchical tree diagram, or "phrase structure tree,"* depicting the abstract grammatical relationships between the words and phrases within a sentence.
2. A system of formal rules specifiying how deep structures are to be transformed into surface structures.
Consider the two sentences "Steven wrote a book on language" and "A book on language was written by Steven." Chomsky held that there is a deeper grammatical structure from which both these sentences are derived. The transformational grammar provides an characterization of this common form and how it is manipulated to produce actual sentences.
Or take the sentence "Who will John see." This corresponds to its surface structure. According to the transformational grammar, we form this sentence by unconsciously applying transformation rules to the underlying deep structure given in the phrase structure tree of the form "John will see who." In this particular case, the transformation rule applied is termed "Wh-movement."
The transformational grammar formed the basis for many subsequent theories of human grammatical knowledge. Since Chomsky's original presentation, many different theories have emerged. Although current theories differ significantly from the original, the notion of a transformation remains a central element in most models.


Verb Phrase
A word or sequence of words consisting of a verb (refers to an
action, existence or occurence) or a verb plus an object
(e.g. 'write', 'write a letter').