Problems of Precision in Fuzzy Theories of Vagueness and Bayesian Epistemology

Abstract

A common objection to theories of vagueness based on fuzzy logics centres on the idea that assigning a single numerical degree of truth—a real number between 0 and 1—to each vague statement is excessively precise. A common objection to Bayesian epistemology centres on the idea that assigning a single numerical degree of belief—a real number between 0 and 1—to each proposition is excessively precise. In this paper I explore possible parallels between these objections. In particular I argue that the only good objection along these lines to fuzzy theories of vagueness does not translate into a good objection to Bayesian epistemology. An important part of my argument consists in drawing a distinction between two different notions of degree of belief, which I call dispositional degree of belief and epistemic degree of belief.