The Lockean Thesis and the Logic of Belief

Abstract

Foley goes on to suggest that rational belief may be just rational degree of confidence above some threshold level that the agent deems sufficient for belief. He finds hints of this view in Locke’s discussion of probability and degrees of assent, so he calls it the Lockean Thesis.1 The Lockean Thesis has important implications for the logic of belief. Most prominently, it implies that even a logically ideal agent whose degrees of confidence satisfy the axioms of probability theory may quite rationally believe each of a large body of propositions that are jointly inconsistent. For example, an agent may legitimately believe that on each given occasion her well-maintained car will start, but nevertheless believe that she will eventually encounter a dead battery.2 Some epistemologists have strongly resisted the idea that such beliefs can be jointly rationally coherent. They maintain that rationality, as a normative standard, demands consistency among all of the agent’s beliefs – that upon finding such an inconsistency, the rational agent must modify her beliefs. The advocates of consistent belief