Econs are presumed to be unboundedly rational, while Humans are boundedly rational. Nevertheless, in certain conditions, Econs aiming to optimize would choose like Humans trying to satisfice. The conditions are imposed by Knightian uncertainty. Although expected utilities are incalculable in these conditions, an Econ could still optimize by relying on a comparative version of decision theory that takes inputs of comparative plausibility and desirability and produces outputs of plausibilistic expectation. The paper shows that comparative decision theory is a special case (...) of heuristics identified by the research programme on simple heuristics. In conditions of Knightian uncertainty, an Econ optimizing with comparative decision theory would make the same decisions as a Human applying these simple heuristics. This result is methodologically relevant for two reasons: comparative decision theory and simple heuristics converge to the same results, and this convergence permits clarification of the relation between normative and descriptive approaches to rational choice. (shrink)

Why should coherence be an epistemic desideratum? One response is that coherence is truth-conducive: mutually coherent propositions are more likely to be true, ceteris paribus, than mutually incoherent ones. But some sets of propositions are more coherent, while others are less so. How could coherence be measured? Probabilistic measures of coherence exist; some are identical to probabilistic measures of confirmation, while others are extensions of such measures. Probabilistic measures of coherence are fine when applicable, but many situations are so information-poor (...) that the requisite probabilities cannot be determined. To measure coherence in these cognitively impoverished situations, this article proposes that the discussion be broadened to include plausibilistic measures of coherence. It shows how plausibilistic measures of coherence can be defined using plausibilistic measures of confirmation. It then illustrates how plausibilisic coherence can be measured in situations where probabilistic coherence cannot be determined. The coherence values obtained through the use of plausibilistic measures are often, though not always, comparable. The article also shows that coherence can be instantiated on different levels, one of which permits connections to inductive strength and deductive validity. (shrink)