If committee members have credences and utilities that differ among the group, then no precise probability-utility pair distinct from the probabilities and utilities of the agents can satisfy the Pareto condition (Seidenfeld, Kadane, and Schervish 1989). The Pareto condition requires that the group preference respect agreement of preference among the group. That is, if all members of the group prefer \(A\) to \(B\) (that is, if each group member finds that \(A\) has higher expected utility than \(B\)) then the aggregate preference (as determined by the aggregate probability-utility pair) should satisfy that preference. Since this “consensus preservation” is a reasonable requirement on aggregation, this result shows that precise models of group agents are problematic. Walley discusses an example of a set of probabilities where each probability represents the beliefs of a member of a group, then \(P\) is an incomplete description of the beliefs of each agent, in the sense that if all members of \(P\) agree on something, then that thing is something each agent believes. Sets of probabilities allow us to represent an agent who is conflicted in their judgements (Levi 1986, 1999).