Gnosiology ("study of knowledge"), a term of 18th-century aesthetics, is "the philosophy of knowledge and cognition". In Soviet and post-Soviet philosophy, the word is often used as a synonym for epistemology. The term is currently used in regard to Eastern Christianity.
The term is derived from the Ancient Greek words gnosis ("knowledge", γνῶσις) and logos ("word" or "discourse", λόγος). Linguistically, one might compare it to epistemology, which is derived from the Greek words episteme ("certain knowledge") and logos.
Alexander Gottlieb Baumgarten (1714–1762) introduced the term "gnosiology" in conjunction with his efforts in the field of aesthetics. The term "gnosiology" is not well known today, although found in Baldwin's (1906) Dictionary of Psychology and Philosophy. The Encyclopædia Britannica (1911) remarks that "The term Gnosiology has not, however, come into general use".
The term "gnosiology" (Modern Greek: γνωσιολογία) is used more commonly in Greek than in English. As a philosophical concept, gnosiology broadly means the theory of knowledge, which in ancient Greek philosophy was perceived as a combination of sensory perception and intellect and then made into memory (called the mnemonic system). When considered in the context of science, gnosiology takes on a different meaning: the study of knowledge, its origin, processes, and validity. Gnosiology being the study of types of knowledge i.e. memory (abstract knowledge derived from experimentation being "episteme" or teachable knowledge), experience induction (or empiricism), deduction (or rationalism), scientific abductive reasoning, contemplation (theoria), metaphysical and instinctual or intuitive knowledge. Gnosiology is focused on the study of the noesis and noetic components of human ontology.
Within gnosiology, gnosis is derived by noesis. Noesis refers to the experiences or activities of the nous. This makes the study and origin of gnosis and gnosiology the study of the intuitive and or instinctual.