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Closure

Epistemic closure is the claim that knowledge is closed under entailment; in other words epistemic closure is a property or the principle that if a subject S {\displaystyle S} knows p {\displaystyle p}, and S {\displaystyle S} knows that p {\displaystyle p} entails q {\displaystyle q}, then S {\displaystyle S} can thereby come to know q {\displaystyle q}. Most epistemological theories involve a closure principle, and many skeptical arguments assume a closure principle. In Proof of An External World, G. E. Moore uses closure in his famous anti-skeptical " here is one hand " argument. Shortly before his death, Wittgenstein wrote On Certainty in response to Moore.

While the principle of epistemic closure is generally regarded as intuitive, philosophers, such as Fred Dretske with relevant alternatives theory and Robert Nozick in Philosophical Explanations, have argued against it.