Global Scepticism, Underdetermination and Metaphysical Possibility

Abstract

I focus on a key argument for global external world scepticism resting on the underdetermination thesis: the argument according to which we cannot know any proposition about our physical environment because sense evidence for it equally justifies some sceptical alternative (e.g. the Cartesian demon conjecture). I contend that the underdetermination argument can go through only if the controversial thesis that conceivability is per se a source of evidence for metaphysical possibility is true. I also suggest a reason to doubt that conceivability is per se a source of evidence for metaphysical possibility, and thus to doubt the underdetermination argument.

Intuitive Dilation?

“…A sample: Carr (ms) calls dilation “an unwelcome result.” Dodd (, p. 72) calls dilation a “puzzling phenomenon.” Bradley (ms) calls it “puzzling” and “strange” and describes dilation as “a fact that fans of imprecise credence must learn to live with.” Cresto (, p. 57) writes, “Reactions to dilation vary widely; while some authors do not seem to be particularly bothered by it, others consider it disastrous for systems that attempt to model epistemic states by means of so‐called ‘imprecise’ probabilities.” Cresto then admits that “some particular examples [of dilation] are indeed hard to swallow.” Luca Moretti calls dilation “a serious and quite distressing problem of imprecise probabilities” (ms) and elsewhere “an unsolved problem of the imprecise probabilities framework, which puts its applicability at risk.” (2014, note 30) Sturgeon () focuses on a version of White's Coin Game and struggles with the “puzzling” and “even more puzzling” counterintuitiveness of dilation in that case.…”