ABSTRACT
Metaphysics is the branch of philosophy concerned with the ultimate nature of reality. In discussing the philosophical underpinnings of psychological theories, it is important to distinguish ontological, epistemological, conceptual issues, which are often intermixed. Conceptual issues are concerned with theoretical analysis the language used to describe and explain observations. Dualism is the common-sense view that there are two distinct realms of mental and physical phenomena. It might be considered an example of ontological idealism if it posits a transcendental realm; or epistemological idealism, insofar as it employs the methods of intuition and contemplation. The ontological claim is that everything that exists consists of matter. In psychology it is primarily an epistemological doctrine, motivated by positivism, a desire for scientific respectability, and put forward originally in 1913 by the American psychologist J. B. Watson. Most current theorists adopt some form of ontological monism but allow conceptual or theoretical dualism; so the same event or process may be described in different ways.
