No nouns, no verbs: psycholinguistic arguments in favor of lexical underspecification

It is often assumed that the primitive units of grammar are words that are marked for grammatical category (e.g., DiSciullo, A.M., Williams, E., 1987. On the Definition of Word: MIT Press, Cambridge, MA). Based on a review of research in linguistics, neurolinguistics, and developmental psychology, we argue that dividing the lexicon into categories such as noun and verb offers no descriptive edge, and adds unnecessary complexity to both the theory of grammar and language acquisition. Specifically, we argue that a theory without lexical categories provides a better account of creative language use and category-specific neurological deficits, while also offering a natural solution to the bootstrapping problem in language acquisition (Pinker, S., 1982. A theory of the acquisition of lexico-interpretive grammars. In: Bresnan, J. (Ed.), The Mental Representation of Grammatical Relations. MIT Press, Cambridge, MA, pp. 655–726).