Summary: Generative Grammar

Sample Picture

In this chapter we have hypothesized that the Grammar of English has a PSR component containing the following set of PSRs which specify the contents of an S, NP, VP, AP, PP, and Det, respectively:

(9) The Sentence Rule

S ------> NP (Aux) VP -------------------------------- (PSR1)

(21) The NP Rule

(30) The VP Rule

(33) The AP Rule

AP ------> (deg) A

(32) The PP Rule

PP -------> P (NP)

(35) The Determiner Rule

By hypothesizing these rules and the lexicon, we make the following claim about what is meant by a "grammatical" sentence or phrase in English. A phrase or sentence is grammatical in English just in case (iff) it can be characterized in terms of a tree diagram which can be generated by some application(s) of the set of PS rules and whose terminal nodes each dominate an appropriate item from the Lexicon. In other words, a sentence is grammatical just in case it can be assigned a structural description by the Grammar containing the PSRs and the Lexicon.

This kind of grammar, which we assume to be a representation of the mind, is called a Generative Grammar, a termed introduced by Chomsky. A grammar generates the set of grammatical sentences in a given language. Though one might think of the word generate in the intuitive sense of produce, this is at most a metaphor. It is important to remember that no claim is being made that we actually have a device in our mind that produces sentences like machines produce consumer products. We don't even claim that our mental grammar is like a computer with programmed instructions (software) that produce sentences (as sentence-generating devices).

We simply take the grammar to be a set of statements that serve to explicitly characterize our knowledge concerning, e.g., what is and what is not a possible member of our language. The PSR's, for example, are not instructions for what to do, but are simply statements of what are the possible (admissible) components of a given category. (E.g., Det, N are the possible components of an NP, etc.; or claims that if X is an English sentence, then X must have a structure of the sort defined by PSR1, etc.) So what is the meaning of generate? Chomsky uses the term in its mathematical sense. In mathematics we say that (a+b)2 generates (a2 + 2ab + b2). There is no sense in which one of these terms produces the other. Rather, (a+b)2 is one way to characterize or specify the properties of (a2 + 2ab + b2). Similarly, when we say our Grammar generates the sentences in our language, we simply mean that our Grammar provides a (proper) characterization for the sentences. In other words, "generates" means "characterizes structurally and formally", or "assigns a (proper) structural description to". The rules are basically statements of permission and prohibition that allow us to describe and explain, in a general way, speakers' knowledge of their languages. A sentence is characterized as grammatical iff it can receive a structural description under the provisions of the Grammar, and ungrammatical otherwise. This is the meaning of a "Generative Grammar".