epistemology

Epistemology is the branch of philosophy concerned with knowledge, belief, and justification. It asks what knowledge is, how it is obtained, and when beliefs count as knowledge.

A traditional formulation is that knowledge is justified true belief, but this has been contested by Gettier counterexamples showing that justified true belief may still fail to be knowledge. This has led to refinements such as requiring reliability or virtuous processes.

Sources and structure: knowledge arises from perception, reason, memory, and testimony. Justification can be foundational (basic beliefs), coherentist (mutual support among beliefs), or reliabilist (trustworthy cognitive processes). Internalism versus externalism debates ask whether justification must be accessible to the thinker or can depend on factors outside their awareness or control.

Historically, rationalism (as in Descartes and Leibniz) emphasizes reason as the primary source of knowledge, while empiricism (as in Locke and Hume) emphasizes sense experience. Kant sought to synthesize these by arguing that knowledge results from the interaction of sensory input with the mind’s concepts.

Contemporary topics include epistemic virtue and responsibility, social epistemology, the epistemology of testimony, the impact of bias, and naturalized epistemology, which connects with cognitive science and the sciences.

Epistemology informs many disciplines, including science, law, and education, and it remains central to debates about skepticism, credibility, and the limits of human knowledge.