Dealing with disagreement: Uniqueness and conciliation

What is the epistemic significance of disagreement? That is, how should discovering that another disagrees with you concerning some proposition affect your credence in that proposition? My dissertation defends a conciliatory view of disagreement.;The first chapter of the dissertation aims to establish the truth of the Uniqueness Thesis. The Uniqueness Thesis claims that a body of evidence justifies at most one competitor doxastic attitude toward any proposition. In this chapter I explain and motivate my formulation of the Uniqueness Thesis, as well as criticize motivations for the Uniqueness Thesis put forward by Roger White. I then defend the Uniqueness Thesis from several extant objections in the literature and note one important consequence of the Uniqueness Thesis. I examine objections from vagueness, the nature of doxastic attitudes, and from the Naive Theory of meaning. This consequence is that if the Uniqueness Thesis is true, then there are no cases where two disagreeing parties have the same evidence, yet each is justified in adopting their competitor doxastic attitude toward the disputed proposition.;In the second chapter I give motivation for accepting a conciliatory view of disagreement. I examine several cases in the literature that provide motivation for such a view. A conciliatory view of disagreement claims that when one becomes justified in believing that an epistemic peer has adopted a competitor doxastic attitude toward a proposition, that one becomes less justified in adopting the doxastic attitude one has toward that proposition.;In the third chapter I examine a series of objections to conciliatory views of disagreement based upon considerations of higher-order evidence. I explain three reasons that Thomas Kelly gives for doubting the truth of such views and argue that each is mistaken. The bulk of this chapter focuses on responding to a canceling-out argument. I explain and motivate two distinct responses to this argument that are compatible with conciliatory views of disagreement.;In the fourth chapter I examine the charge that conciliatory views of disagreement are self-defeating. Such a charge has been made by Plantinga, Elga, and Weatherson. I examine each of these charges individually and argue that there is no reason here to think that conciliatory views of disagreement are false. While it might be true that contingent facts have it that defenders of such views are not justified in believing that their view is correct, this does not show that such views are false. I argue that instead of such views claiming that one becomes less justified in adopting the doxastic attitude one has upon discovering the relevant kind of disagreement, such views should only claim that one gains a reason for becoming less justified. I argue that in cases where one is justified in believing that conciliatory views of disagreement are false, this reason gained from the discovery of a disagreement will itself be defeated and no conciliation will in fact be called for.;In chapter 5 I examine some other circumstances in which one has a defeater-defeater and is not required to make any conciliation after discovering a disagreement of the relevant kind. First, I examine whether considerations involving self-trust are such that in discovering the relevant kind of disagreement one always has a defeater-defeater since one is permitted to trust oneself. I argue that even if self-trust provides a legitimate response to skepticism, it does not provide the relevant defeater-defeater in cases of peer disagreement. Second, I consider whether cases of extreme disagreements give one such a defeater-defeater. I examine several reasons why extreme disagreements might have such a consequence and find all wanting. Finally, I argue that it is plausible that conciliation is to be made in cases of extreme disagreement as well.;In chapter 6 I turn to the issue of how much conciliation is to be made. I argue that in cases of ideal peer disagreement one ought to split the difference. A case of ideal peer disagreement is one where a party of the disagreement is justified in believing that his peer has epistemic credentials x, y, and z and has adopted a competitor attitude toward p, and is as justified in believing these things as he is in believing them about himself. I then strip away the idealized conditions to examine what epistemic impact disagreement has in everyday contexts. While I do not believe that anything true can be said about the non-idealized cases that is both universal and informative, I do make some gestures at what kind of epistemic impact messing with the idealized conditions would have, while noting that how one's evidence adds up on any particular occasion will depend upon what the particular bits of evidence are. (Abstract shortened by UMI.)...