The imprecise probabilist can model the situation as follows: \(P(R)=1/3, P(B)=P(Y)=[0,2/3]\). Note that this expression of the belief state misses out some important details. For example, for all \(p\in P\), we have \(p(B)=2/3-p(Y)\). For the point being made here, this detail is not important. Modelling the ambiguity allows us to rationalise real agents’ preferences for bets on red. To flesh this story out would require a lot more to be said about decision making, (see section 3.3) but the intuition is that aversion to ambiguity explains the preference for I over II and IV over III.