1.NounThe doctrine that consciousness, mental states and processes are simply incidental effects of physiological events in the brain or nervous system and cannot themselves affect the material world. .mw-parser-output .defdate{font-size:smaller}
"How epiphenomenalism views the relationship between thoughts and the brain is akin to how the sound of an engine affects the movement of a car."
2.NounSuch a doctrine, as advanced by a particular thinker or school of thought.