The traditional answer is that an agent that violates the axioms of probability opens herself up, in some sense, to a system of bets that guarantee a sure loss. Answers of this flavor are called Dutch Book arguments. The pragmatic version of the argument posits a tight connection between degrees of belief and betting behavior. The argument concludes by proving a theorem to the effect that an agent would enter into a system of bets guaranteeing a sure loss iff her degrees of belief violate the pr