Evil Daemon

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The Evil Daemon is the name of an argument in philosophy that attempts to prove that the only knowledge one may be certain to possess is knowledge of one's own existence. It was originally proposed by Descartes' in his Meditations on First Philosophy:

"I will suppose. . .that some evil demon of the utmost power and cunning has employed all his energies to deceive me."

From this idea, Descartes demonstrates that due to the unreliability of our senses, we may never be sure that the knowledge which we think we possess, is actually true. Roughly, this skeptical argument can be stated logically as such,

• If we cannot be certain that our senses do not deceive us, then we cannot know anything with certainty.
• We cannot know whether or not our senses deceive us.
• Therefore, we cannot know anything about the world.

According to Descartes' meditations, we cannot know anything a posteriori, i.e. from experience, but can only be certain of knowledge derived through rational means. This prompted Descartes to search for such rational knowledge that did not depend on experience. Perhaps the most famous example of one such rational principle is his statement, "I think, therefore I am".

Skeptical hypotheses
Evil Daemon | Brain in a vat | Dream argument | 5 minute earth
Responses
Here is a hand | Semantic externalism | Process reliabilism | Closure | Contextualism | Relativism