The Physics of Downward Causation

By tradition, physics is a strongly reductionist science. The problem of downward causation from the physicist's point of view is: How can wholes act causatively on parts if all interactions are local? From the viewpoint of a local theory, what is a 'whole' anyway, other than the sum of the parts? This chapter distinguishes between two types of downward causation. The first is whole-part causation, in which the behaviour of a part can be understood only by reference to the whole. The second, called level-entanglement, has to do with higher conceptual levels having causal efficacy over lower conceptual levels.