Tori Hui

The closure principle is pivotal in contemporary epistemology, yet its tenability is subject to ongoing dispute. In particular, both global and local error possibilities challenge the closure principle. Duncan Pritchard seeks to defend a version of the closure principle – _Competent __Deduction Closure_ – by appealing to two ideas. To address local error possibilities, he appeals to the idea of favoring support to save closure; to address global error possibilities, he draws on the concept of hinge commitments in Wittgenstein’s later philosophy. However, upon closer examination, this two-pronged defense proves inadequate. On the one hand, while factive favoring support can address the challenge posed by local error possibilities, non-factive favoring support cannot guarantee that the closure principle holds in all cases. Specifically, there arises an _epistemic sorites point_ at which closure breaks down. On the other hand, although the anti-skeptical hypothesis may be regarded as a hinge commitment that we cannot apply in the _Competent Deduction Closure_, certain cases of transmission failure also amount to closure failure. Thus, the appeal to hinge commitment, while insightful, is ultimately too narrow to rule out all instances of closure failure.