in (i), John is the external argument of the verb buy, and is not part of its maximal projection VP.
(i) John [VP buys books]
An argument of a predicate X which is contained in its maximal projection is called the internal argument. In (i) the NP books is the internal argument of the verb buy.
- Chomsky, N. 1986a. Knowledge of language: its nature, origin and use, Praeger, New York.
- Chomsky, N. 1981. Lectures on Government and Binding, Foris, Dordrecht.
- Williams, E. 1980. Predication, Linguistic Inquiry 11, pp.203-238