From Key Terms in Philosophy of Mind (Continuum, 2010):
mental causation, denied by EPIPHENOMENALISM, the having of effects, by mental phenomena, on any other phenomena, especially physical phenomena. An example would be the production of a bodily motion (a physical event) as a result of an episode of willing (see WILL, THE). (See also ACTION.) Another would be the causing of one mental state by another in a chain of REASONING. More broadly, mental causation concerns the causes of mental phenomena in addition to their effects. On this broader construal, an example would be the production of a PERCEPTION of an avalanche as a causal consequence of an avalanche. That mental phenomena enter into various causal interactions with one another and with nonmental phenomena is a core idea of many varieties of FUNCTIONALISM. For example, one sort of functionalistic thesis holds that what it is to be a BELIEF, and in particular a belief that tigers have stripes, is to be a state of a subject that has various causal relations to other states of the subject, including other states of belief as well as states of sensory reac- tions to striped tigers and states of intention toward certain kinds of behaviors concerning striped tigers. See also EXPLANATORY EXCLUSION; INTERACTIONISM.