Closure, in epistemology, is the principle that if a subject S knows that p, and S knows that p entails q, then S can thereby come to know that q. Most epistemological theories involve a closure principle and many sceptical arguments assume a closure principle, arguing for instance that if you cannot know you are a not a brain in a vat, then you cannot know that you have hands. On the other hand, some epistemologists, including Robert Nozick

Robert Nozick

Robert Nozick was an American political philosopher, most prominent in the 1970s and 1980s. He was a professor at Harvard University. He is best known for his book Anarchy, State, and Utopia , a right-libertarian answer to John Rawls's A Theory of Justice...

, have denied closure principles on the basis of reliabilist

Reliabilism

Reliabilism, a category of theories in the philosophical discipline of epistemology, has been advanced both as a theory of knowledge and of justified belief...

 accounts of knowledge. Nozick, in Philosophical Explanations

Philosophical explanations

Philosophical Explanations is a wide-ranging metaphysical, epistemological, and ethical treatise written by Robert Nozick and published in 1981.-The Parthenon Model and non-coercive philosophy:...

, advocated that, when considering the Gettier problem

Gettier problem

A Gettier problem is a problem in modern epistemology issuing from counter-examples to the definition of knowledge as justified true belief . The problem owes its name to a three-page paper published in 1963, by Edmund Gettier, called "Is Justified True Belief Knowledge?", in which Gettier argues...

, the least counter-intuitive assumption we give up should be epistemic closure. Nozick suggested a "truth tracking" theory of knowledge, in which the x was said to know P iff x's belief in P tracked the truth of P through the relevant modal scenarios

Modal logic

Modal logic is a type of formal logic that extends classical propositional and predicate logic to include operators expressing modality. Modals — words that express modalities — qualify a statement. For example, the statement "John is happy" might be qualified by saying that John is...

.

External links

• The Epistemic Closure Principle at the Stanford Encyclopedia of Philosophy.