Epiphenomenalism does not deny the existence of consciousness, but holds that the interaction between the brain and mind runs strictly one way, from brain to mind. This view was popularized by Darwin’s friend and colleague Thomas Huxley, who described the mind as a mere epiphenomena—a useless by-product of brain activity. According to this theory, free will and intent are only illusions.

Epiphenomenalism does not deny the existence of consciousness, but holds that the interaction between the brain and mind runs strictly one way, from brain to mind. This view was popularized by Darwin’s friend and colleague Thomas Huxley, who described the mind as a mere epiphenomena—a useless by-product of brain activity. According to this theory, free will and intent are only illusions.