Argument (linguistics) - Representing Arguments and Adjuncts

Representing Arguments and Adjuncts

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.