The most widely acknowledged predicative expressions are adjectives and nominals:3
The formulations "over the subject" and "over the object" indicate that the predicative expression is expressing a property that is assigned to the subject or to the object.4 For example, the predicative expression a thief in the last sentence serves to assign to Jill the property of being a thief. Predicative nominals over subjects are also called predicate nominatives, a term borrowed from Latin grammars and indicating the morphological case that such expressions bear (in Latin).
While the most widely acknowledged predicative expressions are adjectives and nominals, most syntactic categories can be construed as predicative expressions, e.g.
There are, however, certain categories that cannot appear as predicative expressions. Adverbs ending in -ly, for instance, cannot appear as predicative expressions, e.g.
These examples raise the following fundamental question: What characteristic of words and phrases allows or prohibits them from appearing as predicative expressions? The answer to this question is not apparent.
Predicative expressions are not attributive expressions. The distinction is illustrated best using predicative and attributive adjectives:5
A given clause usually contains a single predicative expression (unless coordination is involved), but it can contain multiple attributive expressions, e.g. The friendly man found a large snake in his damp bag.
Postpositive adjectives are attributive adjectives which modify the immediately preceding noun or pronoun to create a noun phrase. (A predicate adjective is frequently preceded by a linking verb.) Postpositive adjectives are rare in English, but common in many other languages.
Predicative expressions are typically not arguments, e.g.
The predicative expressions here are properties that are assigned to the subject, whereas the arguments cannot be construed as such properties. Predicative expressions are also typically not adjuncts, e.g.
The predicative expressions again serve to assign a property to the subject, e.g. the property of being under the bed. In contrast, the adjuncts serve to establish the situational context. One can hence acknowledge a three-way distinction between predicative expressions, arguments, and adjuncts. However, upon deeper examination, the lines between these categories become blurred and overlap can occur. For instance, in the sentence Bill arrived drunk, one can judge drunk to be both a predicative expression (because it serves to assign a property to Bill) and an adjunct (because it appears optionally in the sentence).
Predicative expressions exist in most if not all languages. In languages that have morphological case, predicative nominals typically appear in the nominative case (e.g., German and Russian) or instrumental case (e.g. Russian), although predicative expressions over objects generally bear the same case as the object. Some languages lack an equivalent of the copula be, and many languages omit the copula in some contexts or optionally (see zero copula), which means that the case marker plays a greater role since it helps distinguish predicative nominals from argument nominals. Some languages (e.g., Tabasaran, Pacoh) have a separate predicative case.
See for instance Burton-Roberts (1997:79). ↩
See for instance Radford (2004:353). ↩
For an insightful discussion of predicative adjectives and nominals, see Lester (1971:86ff.). ↩
Concerning the fact that predicative expressions express some property of another entity in the sentence, see Hudson (1984:95f.). ↩
See for instance Crystal (1997:303). ↩