Avoid Pronoun Principle
Avoid Pronoun Principle is a principle which states: 'Avoid Pronoun'. This principle, which is considered a subcase of a conversational principle ('don't say more than is required'), is invoked to impose a choice of PRO over an overt pronoun where possible.
This principle explains why his in the sentence does not refer to John, unless it is stressed.
John would much prefer his going to the movie.
Chomsky, Noam A. 1981. Lectures on Government and Binding. Dordrecht:Foris.