Knowing the better, believing the worse: a commitment account of epistemic supererogation

Epistemic supererogation involves going beyond what epistemic rationality requires. If some beliefs can be epistemically supererogatory, then others are epistemically suboptimal yet still rational. In ethics, knowingly doing the suboptimal is commonplace—we often spend money on ourselves rather than giving it to charity. By contrast, existing accounts of epistemic supererogation deny that one could knowingly adopt an epistemically suboptimal attitude. I challenge this assumption and develop a commitment-based account of epistemic supererogation. I focus on cases involving religious, moral, practical, or interpersonal commitments, where the evidence allows more than one rational attitude. In these cases, a longstanding commitment can help explain why someone reasonably sticks with a belief that is epistemically suboptimal. I then consider two ways of explaining this: one on which the belief remains rational because it fits the evidence well enough, and another on which practical factors affect epistemic rationality. This account strengthens the analogy between ethics and epistemology by showing that, in some cases, we can knowingly—and rationally—decline to take the epistemically best option.