 Some refer to EU theory as Bayesian decision theory. This label brings to the forefront the commitment to probabilism, i.e., that beliefs may come in degrees which, on pain of irrationality, can be represented numerically as probabilities. So there is a strong connection between EU theory and probabilism, or more generally between rational preference and rational belief. (The finer details of rational preference and associated rational belief are not the focus here; challenges to EU theory on this front are addressed in  Section 5  below.)