On what we should believe (and when (and why) we should believe what we know we should not believe)

A theory of what we should believe should include a theory of what we should believe when we are uncertain about what we should believe and/or uncertain about the factors that determine what we should believe. In this paper, I present a novel theory of what we should believe that gives normative externalists a way of responding to a suite of objections having to do with various kinds of error, ignorance, and uncertainty. This theory is inspired by recent work in ethical theory in which non-consequentialists 'consequentialize' their theories and then use the tools of decision-theory to give us an account of what we ought (in some sense) to do when we're uncertain about what we ought (in some primary sense) to do. On my proposal, because what we ought to do is acquire knowledge and avoid ignorance, we ought to believe iff the probability of coming to know is sufficiently high. This view has a number of important virtues. Among them, it gives us a unified story about how defeaters defeat (a theory developed with Julien Dutant), explains puzzling intuitions about the differences between lottery cases, preface cases, and cases of perceptual knowledge, and provides externalists (and internalists!) with a general framework for thinking about subjective normativity. It's also relatively brief.