 We have been gradually adding more and more constraints on rational credences, putatively demanded by rationality. Recall that Carnap first assumed that there was a unique confirmation function, and then relaxed this assumption to allow a plurality of such functions. We now seem to be heading in the opposite direction: starting with the extremely permissive orthodox Bayesianism, we are steadily reducing the class of rationally permissible credence functions. So far the constraints that we have admitted have not been especially evidence-driven. Objective Bayesians maintain that a rational agent’s credences are largely determined by her evidence. 