Internalism in epistemology is a thesis about the nature of epistemic normativity, or the sort of normativity that is involved in the evaluation of cognition. Specifically, internalists claim that the (epistemically) normative status of a belief is entirely determined by factors that are relevantly "internal" to the believer's perspective on things. By contrast, externalists in epistemology deny this. The externalist says that the epistemic status of a belief is not entirely determined by factors that are internal to the believer's perspective.

When internalism and externalism are characterized in this way, several things become apparent. First, internalism is a rather strong thesis, in the sense that it says that epistemic status is entirely a function of internal factors. By contrast, the denial of internalism is a relatively weak thesis. Externalism in epistemology holds that some factors that are relevant to epistemic status are not internal...