Downward Causation

"Downward causation" is a term coined by Donald T Campbell ( 'Downward Causation' in hierarchically organised biological systems (1974) ). It refers to the idea that high level emergent phenomena can cause rather than simply reflect the behaviour of constituent parts.

This idea has particular relevance theories of consciousness. If, as many people suggest, phenomenal consciousness is an emergent property then downward causation is necessary to preserve free will and avoid consciousness being an impotent epiphenomenon.

Unfortunately the evidence for the existence of downward causation is at best doubtful. Many examples proposed require a detailed understanding of physics or biology well beyond my personal abilities. However those examples I do understand appear to reduce to indirect effects of the same low level causation that produced the emergent property in the first place. At this point I am not convinced that downward causation exists other than as a useful descriptive modelling technique.