ABSTRACT
The twentieth-century neuroscientist Roger Sperry characterized emergent mental causation like this:
[C]onscious phenomena as emergent functional properties of brain processing exert an active control role as causal determinants in shaping the flow patterns of cerebral excitation. Once generated from neural events, the higher order mental patterns and programs have their own subjective qualities and progress, operate and interact by their own causal laws and principles which are different from and cannot be reduced to those of neurophysiology…. The mental entities transcend the physiological just as the physiological transcends the molecular, the molecular, the atomic and subatomic, etc. The mental forces do not violate, disturb or intervene in neuronal activity but they do supervene.
(Sperry 1980, 201) As described in this passage, mental causation is novel, dependent, harmonious, and unexceptional. (1) Novel: Mental phenomena “transcend the physiological” and manifest distinctive “causal laws and principles” at the psychological level. This results in an “active control role” over neural processes, a point I’ll often put – even if Sperry would not – by saying emergent mental phenomena have novel causal powers, powers that cannot be found among (or reduced to) powers at these lower levels. (2) Dependent: Mental phenomena, while novel, nevertheless depend or “supervene” on the lower-level processes from which they emerge. (3) Harmonious: Emergent mental causation does not disturb or intervene in lower-level causal processes. (4) Unexceptional: Emergent mental causation is one instance of a phenomenon found at many levels of nature, perhaps all levels except (if there is such) the most basic.