Lecture 1: Mind and Body Problems

Mind–body dualism,  in philosophy, any theory that mind and body are distinct kinds of substances or natures. This position implies that mind and body not only differ in meaning but refer to different kinds of entities. Thus, a dualist would oppose any theory that identifies mind with the brain, conceived as a physical mechanism.

The modern problem of the relationship of mind to body stems from the thought of René Descartes, a 17th-century French philosopher and mathematician, who gave dualism its classical formulation. Beginning from his famous Cogito, ergo sum (Latin: “I think, therefore I am”), Descartes developed a theory of mind as an immaterial, nonextended substance that engages in various activities such as rational thought, imagining, feeling, and willing. Matter, or extended substance, conforms to the laws of physics in mechanistic fashion, with the important exception of the human body, which Descartes believed is causally affected by the human mind and which causally produces certain mental events. For example, willing the arm to be raised causes it to be raised, whereas being hit by a hammer on the finger causes the mind to feel pain. This part of Descartes’s dualistic theory, known as interactionism, raises one of the chief problems faced by Descartes: the question how this causal interaction is possible.

This problem gave rise to other varieties of dualism, such as occasionalism and some forms of parallelism that do not require direct causal interaction. Occasionalism maintains that apparent links between mental and physical events are the result of God’s constant causal action.

Parallelism also rejects causal interaction but without constant divine intervention. Gottfried Wilhelm Leibniz, a 17th-century German rationalist and mathematician, saw mind and body as two perfectly correlated series, synchronized like two clocks at their origin by God in a preestablished harmony.

Another dualistic theory is epiphenomenalism, which agrees with other theories in holding that mental events and physical events are different. The epiphenomenalist holds, however, that the only true causes are physical events, with mind as a by-product. Mental events seem causally efficacious because certain mental events occur just before certain physical events and because humans are ignorant of the events in the brain that truly cause them.

Among the difficulties of dualism is the inherent obscurity in conceiving of what sort of thing a mental substance—an immaterial, thinking “stuff”—might be. Such criticisms have led some thinkers to abandon dualism in favour of various monistic theories.

  What are minds, and how are they related to bodies and other physical stuff?

Descartes’ Dualism
    
Descartes contends that a person or human being such as you or me is a two-part composite, of a mind and a body.  (Alternatively speaking, the person is just the mind but has a body.)  And according to him, a mind is an entirely immaterial, nonphysical thing, not even located in physical space.  Yet what unites a mind with a particular body is that it causally interacts with that body, in a distinctively intimate way.
    
His main argument is this:
            1.  I can doubt that my body [or any other physical thing, such as my brain, or anything with any spatial properties] exists.
            2.  I cannot doubt that my mind exists.
        __________________________________________________
         \ 3.  My mind is distinct from my body [and from every other physical thing, such as my brain, or anything with any spatial properties].   [1,2]

Thus, your mind and its states are simply not physical. 

The Interaction problem.  How could a thing so utterly nonphysical as a Cartesian mind directly affect your physical body, or be directly and intimately affected by it? Descartes first appealed to the pineal gland, as the gateway or locus of mind-body interaction.
The pineal gland is just another physical entity; so that appeal is no answer to the question of how a Cartesian mind could interact with anything physical.  Descartes then likened mental causation to the force of gravity; gravity isn’t a physical object like a billiard ball or a fist, yet it causes physical motion.  But gravity is physical in at least the weaker sense that a gravitational field is always the gravitational field of some physical object; also gravity is physical in Descartes’ own favorite sense of being a spatial phenomenon and working according to well known laws of physics.  The trouble with Cartesian minds is that they do not have any spatial properties at all.

Cartesian minds fit ill with our otherwise physical and scientific picture of the world, uncomfortably like ghosts or ectoplasm.  They are not needed for the explanation of any publicly observable fact, for neurophysiology promises to explain the motions of our bodies in particular and to explain them completely.  Ghost-minds are scientific excrescences. Cartesian minds are not scientific posits, hypothesized to explain physical events.  They are known from the inside, and shown to be nonphysical by Descartes’ Doubt argument.  If they’re scientifically ill-behaved, too bad. 

Cartesian Doubt: Cartesian doubt is methodological. Its purpose is to use doubt as a route to certain knowledge by finding those things which could not be doubted. The fallibility of sense data in particular is a subject of Cartesian doubt.
René Descartes, the originator of Cartesian doubt, automatically put all beliefs, ideas, thoughts, and matter in doubt. He showed that his grounds, or reasoning, for any knowledge could just as well be false. Sensory experience, the primary mode of knowledge, is often erroneous and therefore must be doubted. For instance, what one is seeing may very well be a hallucination. There is nothing that proves it cannot be. In short, if there is any way a belief can be disproved, then its grounds are insufficient. From this, Descartes proposed two arguments, the dream and the demon.
Descartes, knowing that the context of our dreams, while possibly unbelievable, is often life-like, hypothesized that humans can only believe that they are awake. There are no sufficient grounds by which to distinguish a dream experience from a waking experience. For instance, Subject A sits at her computer, typing this article. Just as much evidence exists to indicate that her composing this article is reality as there is to demonstrate the opposite. Descartes conceded that we live in a world that can create such ideas as dreams. However, by the end of The Meditations, he concludes that we can distinguish dream from reality at least in retrospect
Descartes reasoned that our very own experience may very well be controlled by an evil demon of sorts. This demon, or genius, is powerful enough to control anybody. He could have created a superficial world that we may think we live in.