Abstract

Are there ever good epistemic reasons to neglect base rates? Assuming an empiricist modal epistemology, I argue that we face an interesting tension between some very plausible epistemic norms: a norm requiring us to proportion our beliefs to the evidence may facilitate knowledge of the actual world, whilst inhibiting our acquisition of modal knowledge—knowledge of how things could be, but are not. The potential for this tension in our epistemic norms is a significant result in its own right. It can also rationalize certain forms of demographic base-rate neglect.