Abstract

In Decision Theory as Philosophy, Mark Kaplan reissues a number of perennial questions within decision theory and epistemology, particularly regarding the relevance of decision theory to epistemology and the scope of an epistemology informed by a “modest” Bayesian decision theory. Much of Kaplan’s book represents a challenge to what he calls the “Orthodox” Bayesian theory of decision and evidence. His arguments turn positive in the fourth chapter, in which he argues for the “Assertion View” of belief---an attempted reconciliation of the categorical notion of belief (as distinct from disbelief) with that of confidence, which comes in degrees. Theapproach to epistemology manifest in Decision Theory, while commendable in some respects, suffers fundamentally from its methodological commitment to the primacy of preference principles over and above distinctively epistemic principles. But to express this last misgiving is just to doubt whether decision theory has much of its own to contribute to epistemology.