Argument (linguistics)

Linguistic terminology

In linguistics, an argument is an expression that helps complete the meaning of a predicate, the latter referring in this context to a main verb and its auxiliaries. In this regard, the complement is a closely related concept. Most predicates take one, two, or three arguments. A predicate and its arguments form a predicate argument structure. The discussion of predicates and arguments is associated most with (content) verbs and noun phrases (NPs), although other syntactic categories can also be construed as predicates and as arguments. Arguments must be distinguished from adjuncts. While a predicate needs its arguments to complete its meaning, the adjuncts that appear with a predicate are optional; they are not necessary to complete the meaning of the predicate. Most theories of syntax and semantics acknowledge arguments and adjuncts, although the terminology varies, and the distinction is generally believed to exist in all languages. Dependency grammars sometimes call arguments actants, following Lucien Tesnière (1959). The area of grammar that explores the nature of predicates, their arguments, and adjuncts is called valency theory. Predicates have a valence; they determine the number and type of arguments that can or must appear in their environment. The valence of predicates is also investigated in terms of subcategorization.

Psycholinguistic theories must explain how syntactic representations are built incrementally during sentence comprehension. One view that has sprung from psycholinguistics is the argument structure hypothesis (ASH), which explains the distinct cognitive operations for argument and adjunct attachment: arguments are attached via the lexical mechanism, but adjuncts are attached using general (non lexical) grammatical knowledge that is represented as phrase structure rules or the equivalent. Argument status determines the cognitive mechanism in which a phrase will be attached to the developing syntactic representations of a sentence. Psycholinguistic evidence supports a formal distinction between arguments and adjuncts, for any questions about the argument status of a phrase are, in effect, questions about learned mental representations of the lexical heads.

A further division blurs the line between arguments and adjuncts. Many arguments behave like adjuncts with respect to another diagnostic, the omission diagnostic. Adjuncts can always be omitted from the phrase, clause, or sentence in which they appear without rendering the resulting expression unacceptable. Some arguments (obligatory ones), in contrast, cannot be omitted. There are many other arguments, however, that are identified as arguments by the relative clause diagnostic but that can nevertheless be omitted, e. g.

a. She cleaned the kitchen. b. She cleaned. – the kitchen is an optional argument. a. We are waiting for Larry. b. We are waiting. – for Larry is an optional argument. a. Susan was working on the model. b. Susan was working. – on the model is an optional argument. The relative clause diagnostic would identify the constituents in bold as arguments. The omission diagnostic here, however, demonstrates that they are not obligatory arguments. They are, rather, optional. The insight, then, is that a three way division is needed. On the one hand, one distinguishes between arguments and adjuncts, and on the other hand, one allows for a further division between obligatory and optional arguments.

The distinction between arguments and adjuncts is often indicated in the tree structures used to represent syntactic structure. In phrase structure grammars, an adjunct is "adjoined" to a projection of its head predicate in such a manner that distinguishes it from the arguments of that predicate. The distinction is quite visible in theories that employ the X bar schema, e. g.

The complement argument appears as a sister of the head X, and the specifier argument appears as a daughter of XP. The optional adjuncts appear in one of a number of positions adjoined to a bar projection of X or to XP. Theories of syntax that acknowledge n ary branching structures and hence construe syntactic structure as being flatter than the layered structures associated with the X bar schema must employ some other means to distinguish between arguments and adjuncts. In this regard, some dependency grammars employ an arrow convention. Arguments receive a "normal" dependency edge, whereas adjuncts receive an arrow edge. In the following tree, an arrow points away from an adjunct toward the governor of that adjunct:

The arrow edges in the tree identify four constituents (= complete subtrees) as adjuncts: At one time, actually, in congress, and for fun. The normal dependency edges (= non arrows) identify the other constituents as arguments of their heads. Thus Sam, a duck, and to his representative in congress are identified as arguments of the verbal predicate wanted to send.

The notion of argument structure was first conceived in the 1980s by researchers working in the government–binding framework to help address controversies about arguments.

The distinction between arguments and adjuncts is crucial to most theories of syntax and grammar. Arguments behave differently from adjuncts in numerous ways. Theories of binding, coordination, discontinuities, ellipsis, etc. must acknowledge and build on the distinction. When one examines these areas of syntax, what one finds is that arguments consistently behave differently from adjuncts and that without the distinction, our ability to investigate and understand these phenomena would be seriously hindered. There is a distinction between arguments and adjuncts which is not really noticed by many in everyday language. The difference is between obligatory phrases versus phrases which embellish a sentence. For instance, if someone says "Tim punched the stuffed animal", the phrase stuffed animal would be an argument because it is the main part of the sentence. If someone says, "Tim punched the stuffed animal with glee", the phrase with glee would be an adjunct because it just enhances the sentence and the sentence can stand alone without it.