 Pascal (ca. 1658/2004) applied the new probability calculus to intensely personal questions of faith. Indeed, many epistemologists are not particularly interested in norms for scientific inquirers, but in the norms governing the entire belief system of an individual: how their beliefs must cohere in order to be rational; how they must be reflected in decision making; and how they ought to accommodate new evidence. Subjective probability theory and its accompanying theory of rational decision is the most comprehensive contemporary expression of this project; for better or worse, it is by far the dominant theory of practical rationality of our day. We introduce it in Section 3.1. 