Mind, Brain, Monism, Dualism
The Evolution of the Soul (Clarendon Press: 1986), p. 191.
There is a crucial difference between these two cases. All other integrations into a super-science, of sciences dealing with entities and properties apparently qualitatively very distinct, was achieved by saying that really some of the entities and properties were not as they appeared to be; by making a distinction between the underlying (not immediately observable) entities and properties and the phenomenal properties to which they give rise. Thermodynamics was conceived with the laws of temperature exchange; and temperature was supposed to be a property inherent in an object. The felt hotness of a hot body is indeed qualitatively distinct from particle velocities and collisions. The reduction was achieved by distinguishing between the underlying cause of the hotness (the motion of the molecules) and the sensations which the motion of molecules cause in observers. The former falls naturally within the scope of statistical mechanics — for molecules are particles; the entities and properties are not now of distinct kinds. But this reduction has been achieved at the price of separating off the phenomenal from its causes, and only explaining the latter.