  Subjectivists have studied the second, inferential phase of the learning process in great detail. Here immediate belief changes are seen as imposing constraints of the form "the posterior probability Q has such-and-such properties." The objective is to discover what sorts of constraints experience tends to impose, and to explain how the person's prior opinions can be used to justify the choice of a posterior probability from among the many that might satisfy a given constraint. Subjectivists approach the latter problem by assuming that the agent is justified in adopting whatever eligible posterior departs minimally from her prior opinions. This is a kind of "no jumping to conclusions" requirement. We explain it here as a natural result of the idea that rational learners should proportion their beliefs to the strength of the evidence they acquire.