Causal closure

Physical causal closure is a metaphysical theory about the nature of causation in the physical realm with significant ramifications in the study of metaphysics and the mind. In a strongly stated version, physical causal closure says that "all physical states have pure physical causes" — Jaegwon Kim, or that "physical effects have only physical causes" — Agustin Vincente, p. 150. Those who accept the theory tend, in general although not exclusively, to the physicalist view that all entities that exist are physical entities. As Karl Popper says, "The physicalist principle of closedness of the physical ... is of decisive importance and I take it as the characteristic principle of physicalism or materialism." Definition Physical causal closure has stronger and weaker formulations. The stronger formulations assert that no physical event has a cause outside the physical domain — Jaegwon Kim. That is, they assert that for physical events, causes other than physical causes do not exist. (Physical events that are not causally determined may be said to have their objective chances of occurrence determined by physical causes.)