Heim (1991) postulated the principle MAXIMIZE PRESUPPOSITION (MP), which has proven useful in the explanation of a range of phenomena But what kind of principle is MP? Is it a normative constraint on language use, akin to a rule in a game? Or is it similar to Grice's MAXIMS OF CONVERSATION, which capture defeasible tendencies in behavior motivated by general considerations about cooperative communication? I argue that either construal faces significant challenges, and provide an alternative conception of MP as a 'linguistic preference' – a (selfish) preference between linguistic forms that speakers happen to have. In this view, MP is neither a normative rule nor a Gricean maxim, but it functions like, and interacts with, such maxims in pragmatic reasoning.