 Dutch Books have also been used to show that there are limitations on the proper applications of credences within the standard decision theoretic framework. Given that the available evidence often appears to dictate only vague or interval-valued credences, it has been argued that rationality permits having such unsharp credences. Elga uses a kind of reverse Dutch Book involving a series of bets that are sure to result in a net gain for the agent to argue that credences must be sharp (Elga 2010). The idea is that a rational agent must accept at least one of the bets in the series, but that there does not appear to be a satisfactory set of decision rules for unsharp credences with this consequence.