In philosophy, emergentism is the belief in emergence, particularly as it involves consciousness and the philosophy of mind, and as it contrasts (or not) with reductionism. A property of a system is said to be emergent if it is in some sense more than the "sum" of the properties of the system's parts. An emergent property is said to be dependent on some more basic properties (and their relationships and configuration), so that it can have no separate existence. However, a degree of independence is also asserted of emergent properties, so that they are not identical to, or reducible to, or predictable from, or deducible from their bases. The different ways in which the independence requirement can be satisfied lead to various sub-varieties of emergence.

All varieties of emergentism strive to be compatible with physicalism, the theory that the universe is composed exclusively of physical entities, and in particular with the evidence relating changes in the brain with changes in mental functioning. As a theory of mind (which it is not always), emergentism differs from idealism, eliminative materialism, identity theories, neutral monism, panpsychism and substance dualism, whilst being closely associated with property dualism. In particular, the dependence of an emergent mind on its base means there is no metaphysical possibility of life after death, in contrast with substance dualism. It is generally not obvious whether an emergent theory of mind embraces mental causation or must be considered epiphenomenal.

Barry Loewer is a philosopher and Chairperson of the Rutgers University Department of Philosophy and director of the Rutgers Center for Philosophy and the Sciences. He obtained his BA from Amherst College (1965) and his PhD from Stanford (under the direction of Jaakko Hintikka). Loewer has published in many areas of philosophy including philosophy of mind, metaphysics, epistemology, history of philosophy, philosophical logic, philosophy of language, and the philosophy of science. He is especially known for work on mental causation, the metaphysics of laws and chance, and the interpretation of quantum mechanics. Loewer has collaborated with Marvin Belzer (on deontic logic), Ernest Lepore (on philosophy of language), and David Albert (on the interpretation of quantum mechanics and the role of chance in statistical mechanics). In his work with Albert he is known for developing the "many-minds interpretation" of quantum theory. The point of this work was not so much to advocate this view as to argue that many worlds interpretations need to be modified to accommodate probabilities. This has become a much discussed and contended issue.