A concept introduced by Donald T. Campbell (1916-1996) in 1974 in order to combat radical reductionism and the excesses of bottom-up explanations as provided by genetic determinism. It is evident when a higher level of a system determines the behavior of lower levels of organization. Under this influence, all processes at lower levels are constrained to act according to the laws of the higher level. However, determination is not complete as the whole is to some degree constrained by the lower levels (upward or bottom-up causation), but at the same time the parts are to some degree constrained by the whole (downward or top-down causation). Such a ‘two-way causation’ is said to typify the behavior of complex systems.
See Causality (in philosophy), Causality (as a psychological phenomenon), Circular (or non-linear) causality, Holism, Levels of analysis, Levels of organization, Open system, Paradigm, Reductionism