A sceptical hypothesis is a hypothetical situation which can be used in an argument for scepticism 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. Sceptical hypotheses have received much attention in modern Western philosophy.
Some of the prominent sceptical hypotheses in Western philosophy include: evil dæmon, brain in a vat, and the five minute hypothesis.