Approximating Ideal Rationality with Multiple Norms

Abstract

Abstract Chapter 6 considers views on which being ideally rational requires more than just being coherent. While extreme subjective Bayesians think that the coherence norm is the only requirement of epistemic rationality, more moderate proponents defend further requirements, such as versions of the Indifference Principle or the Principal Principle. This raises the question of how we can measure approximations to rationality, when being ideally rational requires thinkers to comply with multiple different epistemic norms. Different approaches to justifying norms of rationality are distinguished by whether they assume that there is a single epistemic value or good that explains the various requirements of rationality, or whether there are multiple epistemic values or goods that have to be aggregated somehow in evaluating the rationality of epistemic states. Each view of how epistemic values give rise to norms of rationality is then paired with a suitable strategy for measuring approximations to ideal rationality.