ACCURACY AND UR-PRIOR CONDITIONALIZATION

Abstract

AbstractRecently, several epistemologists have defended an attractive principle of epistemic rationality, which we shall callUr-Prior Conditionalization. In this essay, I ask whether we can justify this principle by appealing to the epistemic goal of accuracy. I argue that any such accuracy-based argument will be in tension withEvidence Externalism, i.e., the view that agent’s evidence may entail nontrivial propositions about the external world. This is because any such argument will crucially require the assumption that, independently of all empirical evidence, it is rational for an agent to be certain that her evidence will always include truths, and that she will always have perfect introspective access to her own evidence. This assumption is incompatible withEvidence Externalism. I go on to suggest that even if we don’t acceptEvidence Externalism, the prospects for any accuracy-based justification forUr-Prior Conditionalizationare bleak.