This paper discusses the Uniqueness Thesis, a core thesis in the epistemology of disagreement. After presenting uniqueness and clarifying relevant terms, a novel counterexample to the thesis will be introduced. This counterexample involves logical disagreement. Several objections to the counterexample are then considered, and it is argued that the best responses to the counterexample all undermine the initial motivation for uniqueness.

An argument structure that covers both cases Gettier described in his 1963 paper reinforces the conclusion of my 2012 Logos & Episteme article that the justified true belief (JTB) conception of knowledge is inconsistent. The stronger argument makes possible identification of fundamental flaws in the standard approach of adding a fourth condition to JTB, so that a new kind of skepticism becomes inevitable unless conceptual change occurs.

Bayesian epistemologists support the norms of probabilism and conditionalization using Dutch book and accuracy arguments. These arguments assume that rationality requires agents to maximize practical or epistemic value in every doxastic state, which is evaluated from a subjective point of view (e.g., the agent’s expectancy of value). The accuracy arguments also presuppose that agents are opinionated. The goal of this paper is to discuss the assumptions of these arguments, including the measure of epistemic value. I have designed AI agents based on the Bayesian model and a nonmonotonic framework and tested how they achieve practical and epistemic value in conditions in which an alternative set of assumptions holds. In one of the tested conditions, the nonmonotonic agent, which is not opinionated and fulfills neither probabilism nor conditionalization, outperforms the Bayesian in the measure of epistemic value that I argue for in the paper (α -value). I discuss the consequences of these results for the epistemology of rationality.

My main aim in this paper is to show that Kolodny’s intriguing argument against wide-scopism – ‘the Reasoning Argument’ – fails. A proper evaluation of the Reasoning Argument requires drawing two significant distinctions, one between thin and thick rational transitions and the other between bare-bones wide-scopism (and narrow-scopism) and embellished wide-scopism (and narrow-scopism). The Reasoning Argument is intended by Kolodny both as an argument against bare-bones wide-scopism and as an argument against embellished wide-scopism. I argue that despite its formidable virtue of demonstrating the need for an account of thick subjective rationality, the Reasoning Argument works neither against bare-bones wide-scopism nor against embellished wide-scopism.

Epistemological contextualism states that propositions about knowledge, expressed in sentences like “S knows that P,” are context-sensitive. Schaffer (2005) examines whether one of Lewis’ (1996), Cohen’s (1988) and DeRose’s (1995) influential contextualist accounts is preferable to the others. According to Schaffer, Lewis’ theory of relevant alternatives succeeds as a linguistic basis for contextualism and as an explanation of what the parameter that shifts with context is, while Cohen’s theory of thresholds and DeRose’s theory of standards fail. This paper argues that Schaffer’s analysis is unsatisfactory since it fails to show that thresholds and standards cannot cope with skepticism, as it is ultimately the conversation participants who control how the conversation plays out. Moreover, Schaffer fails to show that gradability is of no importance in inquiries.