An ‘Evidentialist’ Worry About Joyce's Argument for Probabilism

Abstract

Joyce (1998) argues that for any credence function that doesn't satisfy the probability axioms, there is another function that dominates it in terms of accuracy. But if some potential credence functions are ruled out as violations of the Principal Principle, then some non-probabilistic credence functions fail to be dominated. We argue that to fix Joyce's argument, one must show that all epistemic values for credence functions derive from accuracy. 1. Some background on arguments for probabilism Probabilism asserts that every epistemically rational agent S's 'degrees of confi- dence' (a.k.a., 'degrees of credence' or 'credences') should be faithfully repre- sentable via some probability function b from the set of propositions in S's doxastic space to the real numbers. All of the arguments for probabilism that one finds in the literature are of the following (rough-and-ready) general form: