 Given that a probability function can also be derived from preferences, a similar question arises about the nature and determination of the probability function. One could hold that the probability function represents some real-world quantity, such as partial belief; or one could hold that the probability function is merely a way of representing some feature of betting behavior. There is also disagreement about what facts are relevant to determining someone’s probability function: some hold that it is determined from betting behavior or from the deliverances of a representation theorem while others take it to be primitive (see Eriksson &amp; Hájek 2007).