Epistemology (i/ᵻˌpɪstᵻˈmɒlədʒi/; from Greek , epistēmē, meaning "knowledge", and , logos, meaning "logical discourse") is the branch of philosophy concerned with the theory of knowledge.
Epistemology studies the nature of knowledge, justification, and the rationality of belief. Much of the debate in epistemology centers on four areas: (1) the philosophical analysis of the nature of knowledge and how it relates to such concepts as truth, belief, and justification, (2) various problems of skepticism, (3) the sources and scope of knowledge and justified belief, and (4) the criteria for knowledge and justification.