Recent work on the epistemology of disagreement has focused on doxastic disagreement between epistemic peers: cases where equally knowledgeable and capable agents discover that they have opposing beliefs or credences. In part one of the dissertation, I argue that this narrow focus has created large blind spots and serious mistakes in our understanding of disagreement's epistemic significance. In response, I propose a more comprehensive, Reasons-Based epistemology of disagreement, according to which agents should first attend to the reasons or causes that gave rise to the disagreement, rather than first attending to their interlocutor's epistemic credentials.

In part two of the dissertation, I focus on moral disagreement. There are various metaethical positions that would seem to pose problems for treating moral disagreements as epistemically significant in just the same way as disagreements over more uncontroversially objective matters. For example, one might think that encountering a disagreement about who will win an election (a strictly empirical question) is importantly different from encountering a disagreement about who ought to win the election, all things considered (a question laden with moral value). I push back on this general idea. It turns out that various metaethical positions that might appear have serious implications for the epistemic significance of moral disagreement are not so consequential at all.