Why Dreaming Worlds aren’t Nearby Possible Worlds

Abstract

A familiar anti-sceptical response (à la Sosa) to radical sceptical scenarios employs the safety of knowledge. Radical sceptical scenarios are purported to be too modally remote to really threaten knowledge of ordinary propositions. Why? Because knowledge requires safety, and safety requires the target belief to be true in all nearby possible worlds, but radical sceptical scenarios purportedly take place at distant possible worlds. Hence, the safety theorist claims that radical sceptical scenarios don’t challenge our knowledge of ordinary propositions. But it's alleged by Sosa and others that there's one radical sceptical scenario that can’t be dismissed so easily: the dream scenario. After all, unlike evil demons and brains in vats, ‘dreaming is a daily part of our lives…it is too close for comfort’. In this paper, I sketch an argument to the effect that there's good reason to think that the dream of dream scepticism describes a modally remote possibility, in which case I argue that if the safety-based anti-sceptical response is successful against the evil demon sceptical scenario, the brain in a vat sceptical scenario, and other Cartesian sceptical scenarios in this mould, then it's successful against the dream sceptical scenario as well.