This is the “betting interpretation”. This is the interpretation behind Dutch book arguments: this interpretation of belief makes the link between betting quotients and belief strong enough to sanction the Dutch book theorem’s claim that beliefs must be probabilistic. Williamson in fact takes issue with IP because IP cannot be given this betting interpretation (2010: 68–72). He argues that Smith’s and Walley’s contributions notwithstanding (see formal appendix), the single-value betting interpretation makes sense as a standard for credence in a way that the one-sided betting interpretation doesn’t. The idea is that you may refuse all bets unless they are at extremely favourable odds by your lights. Such behaviour doesn’t speak to your credences. However, if you were to offer a single value then this tells us something about your epistemic state. There is something to this idea, but it must be traded off against the worry that forcing agents to have such single numbers systematically misrepresents their epistemic states. As Kaplan puts it