Traditional grammars categorize determiners with either adjectives or pronouns. But determiners are not adjectives. Repeat after me: Determiners are not adjectives. Notional grammars define adjectives as “words that modify nouns.” Adjectives describe attributes of nouns, pronouns, and noun phrases, functioning as noun phrase modifiers, subject complements, and object complements. Determiners provide non-attributive information such as definiteness, familiarity, location, quantity, and number about a nominal form, functioning as determinatives.
Both adjectives and determiners appear within noun phrases as dependents of the noun phrase head. For example, moist cake and the cake are both noun phrases. Moist is an adjective that describes the noun cake. The is a determiner, specifically a definite article, that provides information about the definiteness of the noun cake. Both moist and the appear directly before cake, but the adjective and determiner differ in grammatical form and grammatical function.
First, adjectives show three degrees of modification while determiners do not vary in internal structure. One can have a moist cake, a moister cake, or the moistest cake. The adjective moist has comparative and superlative forms. Determiners do not exhibit morphological change. One can say the cake but not *the-er cake or *the-est cake. Prototypical adjectives express comparative and superlative forms in addition to the positive form. Individual determiners are invariable in form.
- moist cake
- moister cake
- moistest cake
- the cake
- *the-er cake
- *more the cake
- *the-est cake
- *most the cake
Second, determiners are always constituents of a noun phrase. Adjectives can function as complements, specifically subject complements and object complements. For example, the adjective blue in my house is bright blue functions as the subject complement. Blue is the head of the adjective phrase bright blue and is not a constituent of a noun phrase. Determiners cannot function as complements. *My house is the is grammatically impossible.
- My house is bright blue.
- *My house is the.
Third, determiners are a closed class, and adjectives are an open class. New words are added rarely, if ever, to closed classes. English has a finite number of determiners. New adjectives are added to the language frequently. For example, cromulent and bootylicious, are recent additions to the category of English adjectives. In contrast, the third person plural possessive determiner their is a more recent addition to the category of English determiners, entering the language from Old Norse around the thirteenth century.
Determiners Versus Pronouns
A final note on determiners versus pronouns. Some determiners are identical in form to related pronouns. For example, some possessive determiners in English are his, its, and whose. His, its, and whose are also forms of possessive pronouns. Compare the little girl is his child and the little girl is his. In the first sentence, his is a possessive determiner that provides information about the relationship to the noun child. In the second sentence, his is a possessive pronoun that takes the place of the noun phrase his child.
- The little girl is his child. (possessive determiner)
- The little girl is his. (possessive pronoun)
To determine the syntactic category of a word, one must consider the form, function, and syntax of a word in comparison to other words and phrases. Determiners differ significantly from adjectives. Determiners are invariable in form; adjectives show three degrees of comparison. Determiners are always constituents of a noun phrase; adjectives can function as subject complements and object complements. Determiners are a closed class; adjectives are an open class. Therefore, determiners are not adjectives.
Brinton, Laurel J. & Donna M. Brinton. 2010. The linguistic structure of Modern English, 2nd edn. Amsterdam: John Benjamins Publishing Company.
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.