 Since there are many different measures that reflect the basic idea of the value of true belief how are we to decide between them? We have here a familiar problem of underdetermination. Joyce (1998) lays down a number of desiderata, most of them very plausible, for a measure of what he calls the accuracy of a cognitive state. These desiderata are satisfied by the \(Cv^2\) but not by \(Cv^1\). In fact all the members of a family of closely related measures, of which \(Cv^2\) is a member, satisfy Joyce’s desiderata: