Predicate (grammar)

There are two competing notions of the predicate in theories of grammar. The competition between these two concepts has generated confusion concerning the use of the term predicate in theories of grammar. This article considers both of these notions.

The first concerns traditional grammar, which tends to view a predicate as one of two main parts of a sentence, the other part being the subject; the purpose of the predicate is to complete an idea about the subject, such as what it does or what it is like.

The second notion was derived from work in predicate calculus (predicate logic, first order logic) and is prominent in modern theories of syntax and grammar. In this approach, the predicate of a sentence mostly corresponds to the main verb and any auxiliaries that accompany the main verb; whereas the arguments of that predicate (e.g. the subject and object noun phrases) are outside the predicate.

The predicate in traditional grammar is inspired by propositional logic of antiquity (as opposed to the more modern predicate logic). A predicate is seen as a property that a subject has or is characterized by. A predicate is therefore an expression that can be true of something. Thus, the expression "is moving" is true of anything that is moving. This classical understanding of predicates was adopted more or less directly into Latin and Greek grammars and from there it made its way into English grammars, where it is applied directly to the analysis of sentence structure. It is also the understanding of predicates in English-language dictionaries. The predicate is one of the two main parts of a sentence (the other being the subject, which the predicate modifies). The predicate must contain a verb, and the verb requires or permits other elements to complete the predicate, or it precludes them from doing so. These elements are objects (direct, indirect, prepositional), predicatives, and adjuncts:

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