PHRASE STRUCTURE GRAMMAR 103
Notice how each line of this analysis represents a specific assignment of fea-
tures designed to reveal the structure of the various parts of this particular sen-
tence. The sentence may consist of a noun phrase and a verb phrase, but what are
these phrases composed of? Each is composed of an individual word, a noun and
a verb, respectively. The final step is to describe the noun and the verb, to list the
actual words that make up the sentence. This set of phrase-structure rules is re-
ferred to as agrammar of the sentence.The process of producing this grammar
reflects the procedures that American linguists used in the 19thcentury to de-
scribe and record tribal languages. It builds a lexicon—a list of words—while
showing how those words fit together to make grammatical sentences.
The sentence grammar for sentence 1 is pretty simple, but it contains
within itself the power to describe quite complex sentences. The key lies in an
important feature of language that phrase-structure grammar utilizes:re-
cursion.With respect to language, recursion conveys the fact that complex
expressions can be analyzed in terms of their simpler components. In addi-
tion, it bases analysis onknowledge of the expected outcome.That is, any
analysis of a sentence begins with the completed sentence, not with an ab-
straction, and not with some unknown endpoint. It is like solving a math prob-
lem while knowing the answer in advance.The goal is not to discover the
answer but to understand the steps leading to it.
The advantages these features lend to analysis become clearer if we look at a
series of increasingly complex sentences and adjust the initial rule in ways that
allow us to describe each of them grammatically:
- Fred bought a suit.
The analysis begins with the first phrase-structure rule:SÆNP VPNotice, again, that we are not attempting to show how the sentence ought to
fit together but rather how it does. On this account, our phrase-structure analy-
sis must describe the existing sentence while generalizing in ways that also al-
low us to describe sentence 1.
First, sentences 1 and 2 reflect differences in the verb phrase—one has an object
and the other does not. We have to conclude that NP is an optional element in the
verb phrase. Second, sentences 1 and 2 reflect differences in the noun phrase. The
object NP in sentence 2 has a determiner (det), the indefinite article (art)a,whereas
there were no determiners in sentence 1, and, indeed, there is no determiner in the
subject NP of sentence 2. We therefore have to conclude that determiners are op-
tional elements. Phrase-structure grammar uses a convention for optional ele-