Epistemology

Epistemology, the philosophical study of the nature, origin, and limits of human knowledge. The term is derived from the Greek epistm ("knowledge") and logos("reason"), and accordingly the field is sometimes referred to as the theory of knowledge. Epistemology has a long history within Western philosophy, beginning with the ancient Greeks and continuing to the present. Along with metaphysics, logic, and ethics, it is one of the four main branches of philosophy, and nearly every great philosopher has contributed to it.