 There are various alternative, “fuzzier” representations of desire and belief that might be deemed more suitable. Halpern (2003), for instance, investigates different ways of conceptualising and representing epistemic uncertainty, once we depart from probabilities. Presumably there are also various ways to represent uncertain desire. Here the focus will be on just one proposal that is popular amongst philosophers: the use of sets of probability and utility functions to represent uncertainty in belief and desire respectively. This is a minimal generalisation of the standard EU model, in the sense that probability and utility measures still feature. Roughly, the more severe the epistemic uncertainty, the more probability measures over the space of possibilities needed to conjointly represent the agent’s beliefs. This notion of rational belief is referred to as imprecise probabilism (see the entry on  imprecise probabilities).  Likewise, the more severe the evaluative uncertainty, the more utility measures over the space of sure options needed to conjointly represent the agent’s desires. Strictly speaking, we should not treat belief and desire separately, but rather talk of the agent’s incomplete preferences being represented by a set of probability and utility pairs. Recall the requirement that incomplete preferences be coherently extendible (refer back to  Section 1);  on this representation, all the probability-utility pairs amount to candidate extensions of the incomplete preferences.