 Belief Revision is the study of belief change brought about by the acceptance of incoming information that may contradict initial beliefs (Gärdenfors 2003; Ove Hansson 2012; Peppas 2008). The seminal work in this area is due to Alchourrón, Gärdenfors, and Mackinson, or “AGM” (1985). The AGM approach to belief revision characterizes belief change using a number of postulates. Each postulate provides a qualitative account of the belief revision process by saying what must obtain with respect to the agent’s beliefs after revision by an incoming formula F. For example, the AGM Success postulate says that the formulas the agent believes after revision by F must include F itself; that is, the revision always “succeeds” in causing the agent to come to believe the incoming information F. 