Does rationality require logical omniscience? Our best formal theories of rationality imply that it does, but our ordinary evaluations of rationality seem to suggest otherwise. This paper aims to resolve the tension by arguing that our ordinary evaluations of rationality are not only consistent with the thesis that rationality requires logical omniscience, but also provide a compelling rationale for accepting this thesis in the first place.This paper defends an account of apriori justification for beliefs about logic that is designed to explain the thesis that rationality requires logical omniscience.On this account, apriori justification for beliefs about logic has its source in logical facts, rather than psychological facts about experience, reasoning, or understanding.The proposal is that logical truths provide sources of apriori justification to believe those truths that is indubitable, infallible, and indefeasible. This account is designed to explain why rationality requires logical omniscience.This account has important consequences for the epistemic role of experience in the logical domain. On this account, experience is not a source of apriori justification for beliefs about logic, although it can enable one to use apriori justification that one already has in forming justified beliefs about logic. Similarly, experience is not a source of evidence that defeats apriori justification for beliefs about logic, although it can disable one from using apriori justification in forming justified beliefs. In a slogan, the epistemic role of experience in the apriori domain is not a justifying role, but rather an enabling and disabling role.As I will explain, this account has consequences for a wide range of current issues in epistemology, including the connection between justification and truth, the nature of epistemic idealization, the relationship between propositional and doxastic justification, the function of higher--order evidence of one's cognitive imperfection, and the possibility of rational dilemmas.Here is the plan for the paper. Sections 1 & 2 explain and motivate the thesis that rationality requires logical omniscience. Section 3 proposes an account of 2 apriori justification for beliefs about logic that explains this rational requirement.
Sections 4 & 5 respond to objections by drawing a distinction between ideal andnon--ideal standards of rationality. Sections 6 & 7 develop an account of the enabling and disabling role of experience in the epistemology of logic. Sections 8 & 9 explore the implications of this account for the structure of ideal rationality. Section 10 concludes with a summary of the main claims of the paper.
Probabilistic CoherenceA defining feature of probabilistic theories of rationality is the requirement that one's credences, or degrees of confidence, must be probabilistically coherent in the sense that they conform to the axioms of the probability calculus:(1) For every P, pr (P) ≥ 0.(2) If P is a tautology [i.e. a necessary truth], then pr (P) = 1.(3) If P and Q are mutually exc...