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INTRODUCTION
Sentences are structured not only out of words belonging to various word-level categories, but also out of the phrases belonging to the corresponding set of phrasal categories. There exist convincing non-syntactic, syntactic, and semantic evidence in support of the recognition of phrasal categories in natural language. However, we shall not go into such issues here.
Phrasal categories are phrasal entities like NP (Noun Phrase), VP (Verb Phrase), PP (Prepositional Phrase), Adv. P (Adverbial Phrase), and Adj P (Adjectival Phrase). The phrasal category is larger than the lexical category but is lower and immediately dominated by S, which is the sentential structure as shown in (1) below:
1. S
NP VP
As can be observed in (1), S is said to contain two phrasal categories: NP and VP.
In defining the phrasal category, we say that an NP is a phrase that bears a certain relation to a noun that it contains; a VP is a phrase that bears a certain relation to the verb it contains; a PP is a phrase that bears a relation to a preposition that it contains, and so on. Thus, the phrasal category is defined in terms of the lexical category contained in the phrase. The lexical category stands as the head of the phrase, and the phrasal category is designated as the phrasal projection of the lexical category. Hence, we say that every lexical unit owns its phrasal category.
A sentence can be made up of a noun and a verb, as in the following examples:
2. Speed kills.
3. Jesus saves.
4. Road closed.
In examples (2)-(4) above, the sentences are headed by either a noun or a verb. However, such sentences are limited and cannot sustain communication. One of the reasons why this is so is because they are not complete sentences in the right sense of the term. They are better referred to as phrases.
In this unit, we shall use only two major phrasal categories for illustration: the noun phrase and the verb phrase. We are doing this for two reasons. First, a simple sentence usually contains the two categories, so it will be proper to start with the two types of phrasal categories. Second, since we shall consider phrase and clause types in the next unit, we shall reserve our discussion of other phrasal categories in Unit 3.
Noun Phrase
As the name implies, a noun phrase is a construction type that has a noun as its head. A typical noun phrase (NP) could be made up of a noun (head), a determiner (Det), and an adjective (Adj). This could be represented as in (5):
5. NP (Det) + (Adj) + N
Noun phrases may appear in various constituent positions. A noun phrase may serve as the subject, object, or complement as in the following examples:
6. The man is a driver (subject)
7. Ngozi bought a bus (object)
8. The books are treasures (complement)
Notice that in (5) above, the categories Det and Adj are enclosed in brackets. This means that they are optional categories. An NP, therefore, may not contain a Det and/or an Adj, but it must contain a noun. Determiners and adjectives serve as modifiers of the noun phrase. A noun phrase, then, may have a determiner as the modifier of the head (e.g., the man; a man), an adjective as the modifier (e.g., killer drugs; bad boys), and a determiner and an adjective as the modifiers (e.g., the beautiful girl). Sometimes, a determiner and more than one adjective could appear as modifiers (e.g., the tall beautiful girl). The most common sequence in a noun phrase is Det + Adj + N (as in: a fine dress; the small girl; the big table).
In line with what we have discussed above, we can represent the structure of the Noun Phrase using a phrase marker (tree diagram). The following examples can be used as an illustration.
9. a bad boy
10. the tall beautiful girl
(In these examples, the heads are italicized).
The analysis of the above examples will be as follows:
9. NP
Det Adj P N
a bad boy
In the two phrase markers, the headship of the N is acknowledged.
In addition to the foregoing, noun heads can be premodified by adjective phrases as in (11):
11. an extremely long journey
In (11), the head, journey, is premodified by a determiner and adjective phrase, which is further analyzed as adverb and adjective. Note that within the adjective phrase, the adverb, extremely, modifies the adjective, long, which is the head of the adjective phrase. Other examples to illustrate this are:
12. a very foolish black boy
13. these extremely fat girls
The structure of (9) differs a little from that of (11). In this phrase, very foolish and the adjective black do not form a single constituent; each modifies the noun separately, as shown in the phrase marker below:
14. NP
Det Adj P N
Adj
a very foolish black boy
The Adj P consists of a degree adverb and an adjective, which is distinct from the adjective that is closer to the head, N. It follows that the analyses of structures depend on the words that form constituents. Those that belong to the same constituent will have one node label, while those that belong to different constituents will have different node labels.
Apart from premodification, the head nouns can also be postmodified. Usually, prepositional phrases (PP) and subordinate clauses serve as post-modifiers. Consider the following examples:
15. the tin of oil
16. a book on Edo language
17. the shirt which Mike bought is brown
18. the girl who came is a nurse
In (15) and (16), the heads, tin and book respectively, occur before (and are therefore post-modified by) the following prepositional phrases, as illustrated in the phrase marker below:
15. NP
Det
the
PP
P
of
NP
Det N
tin oil
In (17) and (18), relative clauses, which Mike bought and who came, respectively, are inserted in front of their NP antecedents in the matrix sentences. A clause is relativized when an NP within it is identical (and is therefore changed to a relative pronoun). We can represent (17) and (18) in phrase markers as follows:
17. NP
NP S1
Det N
the shirt
NP VP
is
Adj P
brown
S
NP VP
V
N
Mike bought
Det N
the girl
18. NP
NP S1
Det N
the girl
NP VP
is
N
a nurse
S
NP VP
V
who came
Notice that in the two phrase markers (17) and (18), the noun phrases in the matrix sentences are identical with the noun phrases
Summary
In summary, phrasal categories are essential for understanding the structure of sentences in natural language. They are built from lexical categories like nouns and verbs through merger operations. The head of a phrase determines its grammatical properties, and phrases can be expanded by merging additional categories to form larger structures.
Further Considerations
While this discussion has focused on noun phrases and verb phrases, it's important to note that other phrasal categories exist, such as prepositional phrases (PP) and adjectival phrases (AdjP). These can also be expanded and analyzed using similar principles.
Additionally, the recursive nature of phrase structure allows for the generation of complex sentences from simpler components. This recursive property is fundamental to human language and enables the creation of an infinite variety of sentences.
Conclusion
In conclusion, understanding phrasal categories and their formation through merger operations is key to understanding the structure of sentences in natural language. This knowledge forms the basis for more advanced syntactic analyses and provides insights into the underlying mechanisms of human language.
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