The Acquisitional Role of the Syntax-Morphology Interface: Morphological Compounds and Syntactic Complex Predicates

The principal claim of this paper is that a single parameter determines both whether a language permits productive root compounding, and whether the language permits syntactic complex predicates. The relevant parameter meets the classical (Chomsky 1981) criterion of having consequences across a sizable range of superficially disparate grammatical constructions, but is not reducible to the information in the lexical entry for any independently motivated functional head, or other closed-class lexical item. Evidence for the parameter comes from investigation of both child language acquisition and cross-linguistic variation.