Mental causation

Both folk and scientific psychology assume that mental events and properties participate in causal relations. However, considerations involving the causal completeness of physics and the apparent non-reducibility of mental phenomena to physical phenomena have challenged these assumptions. In the case of mental events (such as someone’s thinking about Vienna), one proposal has been simply to identify not ‘types’ (or classes) of mental events with types of physical events, but merely individual ‘token’ mental events with token physical ones, one by one (your and my thinking about Vienna may be ‘realized’ by different type physical states).

The role of mental properties (such as ‘being about Vienna’) in causation is more problematic. Properties are widely thought to have three features that seem to render them causally irrelevant: (1) they are ‘multiply-realizable’ (they can be realized in an indefinite variety of substances); (2) many of them seem not to supervene on neurophysiological properties (differences in mental properties do not always depend merely on differences in neurophysiological ones, but upon relations people bear to things outside their skin); and (3) many of them (for example, ‘being painful’) seem inherently ‘subjective’ in a way that no objective physical properties seem to be. All of these issues are complicated by the fact that there is no consensus concerning the nature of causal relevance for properties in general.