Jonathan Matheson

An introduction to the debate of the epistemic significance of peer disagreement. This article examines the epistemic significance of peer disagreement. It pursues the following questions: (1) How does discovering that an epistemic equal disagrees with you affect your epistemic justification for holding that belief? (e.g., does the evidence of it give you a defeater for you belief?) and (2) Can you rationally maintain your belief in the face of such disagreement? This article explains and motivates each of the central positions, including steadfast views and conciliatory views of peer disagreement, while at the same time raising challenges for each of them. It concludes by speculating about new directions that the debate will take.

In this article, I propose, defend, and apply a principle for applied ethics. According to this principle, we should exercise moral caution, at least when we can. More formally, the principle claims that if you should believe or suspend judgment that doing an action is a serious moral wrong, while knowing that not doing that action is not morally wrong, then you should not do that action. After motivating this principle, I argue that it has significant application in applied ethics. The application to applied ethics comes by way of the epistemic significance of disagreement. Though such a principle has perhaps a number of applications in applied ethics, my focus here is limited to the question of whether it is morally permissible to eat animals for pleasure.

The Uniqueness Thesis, or rational uniqueness, claims that a body of evidence severely constrains one’s doxastic options. In particular, it claims that for any body of evidence E and proposition P, E justifies at most one doxastic attitude toward P. In this paper I defend this formulation of the uniqueness thesis and examine the case for its truth. I begin by clarifying my formulation of the Uniqueness Thesis and examining its close relationship to evidentialism. I proceed to give some motivation for this strong epistemic claim and to defend it from several recent objections in the literature. In particular I look at objections to the Uniqueness Thesis coming from considerations of rational disagreement (can’t reasonable people disagree?), the breadth of doxastic attitudes(can’t what is justified by the evidence encompass more than one doxastic attitude?), borderline cases and caution (can’t it be rational to be cautious and suspend judgment even when the evidence slightly supports belief?), vagueness (doesn’t the vagueness of justification spell trouble for the Uniqueness Thesis?), and degrees of belief (doesn’t a finegrained doxastic picture present additional problems for the Uniqueness Thesis?).

While puzzles concerning the epistemic significance of disagreement are typically motivated by looking at the widespread and persistent disagreements we are aware of, almost all of the literature on the epistemic significance of disagreement has focused on cases idealized peer disagreement. This fact might itself be puzzling since it doesn’t seem that we ever encounter disagreements that meet the relevant idealized conditions. In this paper I hope to somewhat rectify this matter. I begin by closely examining what an idealized case of peer disagreement looks like and what the Equal Weight View (EWV) of disagreement claims about the epistemic significance of such disagreements. After briefly defending the verdicts of the EWV in idealized disagreements I proceed to unpack the implications of stripping away the idealized conditions. In doing I show both why it is important to focus on idealized cases of peer disagreement and what we can learn from such cases that applies to the everyday cases of disagreement of which we are very familiar.