The epistemology of disagreement

Consider two people who disagree about some important claim (e.g. the future moral and political consequences of current U.S. foreign policy are X). They each believe the other person is in possession of the same relevant evidence for the claim, each is equally competent to evaluate it, etc. How should such recognized disagreement affect their attitude towards the original claim? I develop a view which steers a middle course between the two main answers to this question in the literature: the skeptical response developed by Richard Feldman and others and the no-defeater response developed by philosophers such as Thomas Kelly. If successful, I will have shown that (contra the skeptical response) conversing with intelligent friends who disagree with us needn’t have the discouraging result that the justification of our beliefs is undermined. I will have also shown that (contra the no-defeater response) disagreement can significantly affect the degree of justification that our beliefs enjoy. Chapter 1 provides an overview of the main positions on offer in the literature on the epistemology of disagreement. According to the skeptical response, recognized disagreement between two parties, where each believes the other to be an epistemic peer (i.e. roughly equal in intellectual ability, thoughtfulness, and freedom from bias), has the consequence that neither party’s belief (concerning the proposition or propositions about which they disagree) can remain rational. That is, each party has a defeater for her belief (i.e. something, such as another belief or an experience one has, that undermines the rationality or positive epistemic status of a belief). The no-defeater position maintains that the recognition that one’s epistemic peer has arrived at a different judgment concerning some proposition need not undercut the rationality of one’s own belief about that proposition in any way. In chapter 2, I argue that the skeptical response is committed to a false premise, namely that disagreements between epistemic peers usually have the consequence that the epistemic credentials of each party’s belief or beliefs seem to be on a par (all things considered). I also argue that the no-defeater response is intuitively implausible insofar as it suggests that disagreement need never have any direct negative epistemic impact on one’s beliefs. In chapter 3, I argue that the epistemic implications of disagreement between peers are often most plausibly accounted for in terms of partial defeat (a ‘partial defeater’ is something that results in a loss of some, but not all, of the rationality or positive epistemic status of a belief). That is, I contend that many disagreements between epistemic peers have the consequence that each person should lower their degree of confidence in their belief. In the final chapter, I distinguish cases in which disagreement results in a defeater from cases yielding no defeater and from cases where a partial defeater is the result. I argue that what intuitively distinguishes these three kinds of cases is, in general, a function of what it is reasonable to believe concerning the reliability of the other person. I then show how this way of distinguishing these cases falls out of the position on disagreement I’ve been defending in the previous chapters. In short, by focusing on a dynamic account of the epistemological significance of disagreement, I am able to offer a novel view that avoids the difficulties associated with the more extreme positions currently in the literature