The Mind-Body Duality Source: Robert H. Wozniak

Rene Descartes ( )

Mind-Body Dualism  Descartes -- The rational mind connects with the animal body at the pineal gland. Thus, mind affects body and body affects mind. Animals have no minds.  We now know the pineal gland does something else, but…  Is there a “mind” or “soul” independent of the brain?

17 th Century Philosophy (1600’s)  Causes and effects must be of similar types: Physical cause leads to physical effect.  God is the only true cause – Malebranche  Spinoza’s double aspect theory – mind and body are both aspects of God in preestablished coordination.  Leibnitz’s psychophysical parallelism – causation is rejected, coordination remains.

18 th Century Philosophy (1700’s)  All is mind vs. all is body.  Berkeley’s “Immaterialism” – There is no body because all matter is perceived by the mind and can’t be known apart from it.  Materialism – there is no mind, only matter. Mental events don’t exist. La Mettrie, “L’homme machine.” States of the soul depend upon states of the body.

19 th Century Philosophy (1800’s)  Localization of cerebral function showed that the brain is the organ of the mind.  Mental states were shown to affect the body. Trauma, mesmeric trance, mental suggestion.  Huxley’s “Epiphenomenalism” – Mental states have no causal efficacy, like paint on a stone (neurophysiology is the stone, mind is the paint). We are “conscious automata.”

Interactionism  Carpenter – mind and brain interact: Light produces a change in nerves in the brain that results in mental sensation of seeing. Desire to move is translated into commands to the nerves that move muscles in voluntary motion.  There exist circuits between mental and physical activity.  How this is accomplished is unknown.

Dual-Aspect Monism  Lewes – mental and physical processes are two aspects of the same psychophysical event. Mind is subjective while body is objective. Terms used to describe the two are not inter-translatable.  Lewes still provides the best argument for why psychology cannot be replaced by neuroscience.

Mind-Stuff Theory  Higher properties of mind are compounded from mental elements (pieces of mind-stuff).  When molecules come together at a level of complexity sufficient to form a brain and nervous system, correlative mind-stuff forms consciousness.

James’ Idea of Mind-Stuff

William James  James adopted a pragmatic empirical parallelism of the sort many psychologists still support.  The "simplest psycho-physic formula…” is a "blank unmediated correspondence, term for term, of the succession of states of consciousness with the succession of total brain processes..."  Principles of Psychology, p. 182

Ongoing Controversy  We still do not know how “mind” emerges from “body.” The nature of the relationship between specific mental states and the neural substrate is still not understood.  Those debating mind-body today largely express ideas that are versions of the philosophical arguments proposed over the past 250 years.

Interview with Rodney Brooks Human as machine, machine as human: