论拉基辩护主义观对同侪分歧认知意义的理论重构

On Lackey’s Justificationist View as a Theoretical Reconstruction of the Epistemic Significance of Peer Disagreement

摘要: 在同侪分歧(peer disagreement)的认识论争论中，埃尔加提出的对等权重观(equal weight view)主张，即当对话者与认知同侪发生分歧时，双方应给予对方意见同等权重，通常表现为信念折中。然而，极端案例中折中直觉的反常使这一观点面临严峻挑战。拉基提出的辩护主义观(justificationist view)以“辩护性置信度”和“对称性打破者”取代“同侪身份”和“分歧事实”作为核心解释项，将分歧的认识力量条件化。在这个意义上，辩护主义并非对等权重观的简单改进，而是在理论层级上构成对等权重观的上位替代，对等权重观被降格为辩护主义在低辩护性置信度且无对称性打破者条件下的局部推论。同时，辩护主义通过解释对等权重观何时有效、为何有效、何时失效，为对等权重观提供一个更一般的解释框架。对此，从概念分析、案例检验、机制阐述和理论比较四个维度展开论证，同时可以回应辩护主义观引起的偏见合法化、个人信息不可公共检验、自我挫败等反驳。

Abstract: In the epistemological debate over peer disagreement, Adam Elga’s equal weight view holds that when an agent disagrees with an epistemic peer, both parties should give equal weight to each other’s opinions, typically amounting to splitting the difference in credence. However, the counterintuitive nature of conciliatory verdicts in extreme cases poses a serious challenge to this view. Jennifer Lackey’s justificationist view replaces “peerhood” and “the fact of disagreement” with “degree of justified confidence” and “symmetry breaker” as the core explanatory terms, thereby conditionalizing the epistemic force of disagreement. In this sense, justificationism is not a mere improvement on the equal weight view but constitutes a higher-level replacement of it: the equal weight view is demoted to a local corollary of justificationism under conditions of low justified confidence and the absence of a symmetry breaker. At the same time, by explaining when, why, and where the equal weight view is valid and invalid, justificationism provides a more general explanatory framework for it. The argument proceeds along four dimensions: conceptual analysis, case-based examination, mechanistic exposition, and theoretical comparison. It also responds to objections that justificationism licenses bias, that personal information is not publicly verifiable, and that the view is self-defeating.