 Now, suppose \(c^\dag\) is a non-probabilistic credence function and apply the version of Joyce’s argument that results from replacing (2) with (2’). That is, we assume that it is possible that the agent learn with certainty that \(c^\dag\) is the unique rational response to her evidence, even if in fact it is not. We might assume, for instance, that a mischievous God whispers in the agent’s ear that this is the case. Then we must conclude that \(c^\dag\) is not weakly dominated relative to any legitimate measure of epistemic disutility. But now we have that no credence function is weakly dominated, whether it is probabilistic or not. And, combined with Joyce’s other considerations, this is impossible. If no probabilistic credence functions are weakly dominated relative to an epistemic disutility function, then all of the non-probabilistic credence functions are: that’s the lesson of  Theorem 5  above. Of course, the natural response to this objection is to note that (2’) only holds when \(c\) is a probabilistic credence function. But such a restriction is unmotivated until we have established Probabilism.