Epistemic externalism

Externalist views of justification emerged in epistemology during the late 20th century. Externalist conceptions of justification assert that facts external to the believer can serve as the justification for a belief. According to the externalist, a believer need not have any internal access or cognitive grasp of any reasons or facts which make their belief justified. The externalist's assessment of justification can be contrasted with access internalism, which demands that the believer have internal reflective access to reasons or facts which corroborate their belief in order to be justified in holding it. Externalism, on the other hand, maintains that the justification for someone's belief can come from facts that are entirely external to the agent's subjective awareness.

Alvin Goldman, one of the most well-known proponents of externalism in epistemology, is known for developing a popular form of externalism called reliabilism. In his paper, “What is Justified Belief?” Goldman characterizes the reliabilist conception of justification as such:

"If S’s believing p at t results from a reliable cognitive belief-forming process (or set of processes), then S’s belief in p at t is justified.”

Goldman notes that a reliable belief-forming process is one which generally produces true beliefs.

A unique consequence of reliabilism (and other forms of externalism) is that one can have a justified belief without knowing one is justified (this is not possible under most forms of epistemic internalism). In addition, we do not yet know which cognitive processes are in fact reliable, so anyone who embraces reliabilism must concede that we do not always know whether some of our beliefs are justified (even though there is a fact of the matter).