## Abstract

Jon Williamson's Objective Bayesian Epistemology relies upon a calibration norm to constrain credal probability by both quantitative and qualitative evidence. One role of the calibration norm is to ensure that evidence works to constrain a convex set of probability functions. This essay brings into focus a problem for Williamson's theory when qualitative evidence specifies non-convex constraints.

• 1Formal Preliminaries

• 2A Definition without a Procedure

• 3Independence and Epistemic Relevance

• 4Conclusion