Uniqueness and Logical Disagreement

Abstract

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.

Countering Justification Holism in the Epistemology of Logic: The Argument from Pre-Theoretic Universality

“…So, as a statement of UI, instead of having [∀xPx, Γ ⊨ Pa] with Γ empty, they may have something like [∀xPx, E!a ⊨ Pa]. These are two completely general, not relativized, rival principles of universal instantiation, which makes the tension between them a genuine case of logical disagreement (Williamson, 1988;Hattiangadi, 2018;Andersen, 2020;Hjortland, 2022;Rossi, 2023). Some free logicians may accept that [∀xPx ⊨ Pa] in case 'a' is not an empty name, but reject that this is the (correct) principle of universal instantiation, and endorse [∀xPx, E!a ⊨ Pa] instead.…”

Uniqueness and Logical Disagreement (Revisited)

“…This paper is largely based onAndersen (2020), but it includes several important corrections and additions. 2 See for exampleMatheson (2011), Rosa (2012,Kelly (2014),White (2014),Kopec and Titelbaum (2016),Ross (2021),Kauss (2023).3 Roughly put, two agents in disagreement are epistemic peers when neither side is epistemically superior with respect to the target-proposition at hand, i.e., when the two are similar enough in all relevant factors such as evidence, track record, time constraints etc.…”