External-World Skepticism

Classification

Position level

specific

Domains

Epistemology

Overview

Descartes raised the doubt as a first step to be later overcome, but taken on its own it names a durable skeptical position: since any course of experience could in principle be a dream or the work of a deceiver, no perceptual belief about mind-independent things is ever certain. Modern versions replace the deceiver with the brain-in-a-vat, but the structure is the same — nothing in experience can rule the skeptical scenario out. Putnam argued that one version defeats itself: a brain that has always been in a vat could not refer to real vats, so its words "I am a brain in a vat" would be false. The argument is disputed, and even if it works it does not reach someone put in a vat only recently, whose words still refer to vats.

Position on

• Knowledge of the External World

  Even granting that some truths survive doubt, beliefs about a mind-independent world do not, because the dreaming and deceiver scenarios are subjectively indistinguishable from waking veridical experience.

Broader position

• Epistemic Skepticism

Rival positions

• Moorean Common Sense

  Question scope: Knowledge of the External World

References

• René Descartes, Meditations on First Philosophy, Meditation I
• Hilary Putnam, Reason, Truth and History (Cambridge University Press, 1981), ch. 1 ('Brains in a Vat')
• Stanford Encyclopedia of Philosophy, Skepticism and Content Externalism (whether Putnam's argument works, and why it leaves recent envatment untouched)
• René Descartes, Meditations on First Philosophy, Meditation I (the dreaming and evil-deceiver doubts)
• G. E. Moore, 'Proof of an External World', Proceedings of the British Academy 25 (1939), which claims the knowledge of external things that the skeptical conclusion denies
• Stanford Encyclopedia of Philosophy, Skepticism