Philosophical Skepticism - Skeptical Hypotheses

Skeptical Hypotheses

A skeptical hypothesis is a hypothetical situation which can be used in an argument for skepticism about a particular claim or class of claims. Usually the hypothesis posits the existence of a deceptive power that deceives our senses and undermines the justification of knowledge otherwise accepted as justified. Skeptical hypotheses have received much attention in modern Western philosophy.

The first skeptical hypothesis in modern Western philosophy appears in René Descartes' Meditations on First Philosophy. At the end of the first Meditation Descartes writes: "I will suppose... that some evil demon of the utmost power and cunning has employed all his energies to deceive me."

• The "Brain in a vat" hypothesis is cast in scientific terms. It supposes that one might be a disembodied brain kept alive in a vat, and fed false sensory signals, by a mad scientist.
• The "Dream argument" of Descartes and Zhuangzi supposes reality to be indistinguishable from a dream.
• Descartes' Evil demon is a being "as clever and deceitful as he is powerful, who has directed his entire effort to misleading me."
• The five minute hypothesis (or omphalos hypothesis or Last Thursdayism) suggests that the world was created recently together with records and traces indicating a greater age.
• The Simulated reality hypothesis or Matrix hypothesis suggest that we might be inside a computer simulation or virtual reality.