The idea of a separate soul or mind in humans has a long history. The ancient Hebrews used the word “breath” (ruach, which also means “spirit”) to refer to the soul, believing that it was a gift from God that animated us. The ancient Greeks, particularly Pythagoras and Plato, thought that the soul (psyche, from which we get our word “psychology,” the study of the soul) was lodged in the body like a captain of a ship. The soul was the rational and animating principle within us. It was immortal, having neither beginning nor end. When a person died, the soul left the body and was reincarnated in another body. Hinduism holds a similar belief, with the addition that the soul at last will be absorbed into a greater soul in Nirvana. Most Christians throughout the ages have believed that the soul is created by God, animates the body, and will live forever in another realm after death. Other Christians, basing their belief on Paul’s words in 1 Corinthians 15, believe that it is not a separate soul but a resurrected body (a whole, embodied person) that will survive death.
Today these ideas are under attack. Neuroscience studies brain states, which many scientists believe are sufficient to explain mental life. They argue that there is no place or need for a separate soul or mind. If there are correct, our religious heritage needs to be modified or abandoned. But many philosophers argue that there are good reasons for holding to traditional beliefs about the soul or mind and about its survival after death (Louis Pojman, 259).
THE MIND-BODY PROBLEM IN PHILOSOPHY
Intuitively, we seem to distinguish two different types of reality: material and mental, bodies and minds. Bodies are solid, material entities, extended in three-dimensional space, publicly observable, measurable, and capable of causing things to happen in accordance with invariant laws of mechanics. Minds have none of these properties. Consciousness is not solid or material, is not extended in three-dimensional space, does not occupy space at all, and is directly observable only by the person who owns it, cannot be measured, and seems incapable of causing things to happen in accordance with the invariant laws of mechanics. Individuals can only think their own thoughts, feel their own emotions, and suffer their own pain. Although neurosurgeons can open skulls and observe brains, they cannot observe minds, or their beliefs, sensations, emotions, or desires.
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Unlike physical bodies, mental entities have no shape, weight, length, width, height, colour, mass, velocity, or temperature. It would sound odd, indeed, to speak of a belief weighing 16 oz like a box of cereal, or to describe a feeling of love measuring 4 in. ,like a piece of lumber, a pain as heavy as a cement bag or a desire as green and having a temperature of 103oF. yet common sense tells us that these two entities somehow interact. But the question arises, how exactly does this transaction between the mind and brain occur, and where does it occur? Could it be, as materialists contend, that the mind is really simply a function of the body, not a separate substance at all? Or could the idealist monists be correct: the body is really an illusion, and there is only one substance, the mind alone? (Louis Pojman, 260 -261). Rene Descartes and Alfred North Whitehead sought to respond to these questions as we shall see.
THE MIND-BODY RELATION OF RENE DESCARTES
Having rescued himself from skepticism to discover the reality of the world, Rene Descartes sought again to see what sort of reality has been recovered. To get clear on this, Descartes uncritically dredges up the Greek and medieval notion of substance. He defines substance as “a thing which exists in such a way as to depend on no other thing for its existence.” According to Descartes there are two main categories of substances: mental substances and physical substances. This implies that the mind and body are two completely different entities. He (Descartes) started out by being sure of his own mental existence but in doubt as to whether or not his body existed. This led him to conclude that the mind is a separate substance from the body because it does not need the body in order to exist or to be understood.
Furthermore, the mind and the body are separate substances because they have completely different attributes. Minds are capable of conscious acts such as thinking, doubting, and willing. Bodies are not conscious and are simply moved by mechanical forces acting on them. Minds are not extended and so do not take up space. They are a kind of nonphysical or spiritual reality. Because they are not extended, they are not made up of parts and cannot be divided. Bodies, of course, are extended, occupy space, and can be divided into more elementary particles. The picture that emerges is that human beings are made up of two different kinds of reality somehow linked together. According to Descartes, your mind (which is identical to your soul) is the “real” you. If you lose an arm or a leg, your bodily mechanism is impaired but you are still as complete a person as before.
Descartes position here is a kind of dualism. Dualism is the name for any theory that postulates tow kinds of ultimate and irreducible principles or elements. More specially, what we have here is metaphysical dualism. Metaphysical dualism refers to any theory that claims that there are two ultimate and irreducible kinds of reality. To be even more specific, because Descartes theory concerns the relationship between the mind and the body, it can be called mind-body dualism or psychophysical dualism and now (after Descartes’ classical statement of this position) called Cartesian dualism in his honour. This dualistic scheme has sometimes been called the “Cartesian compromise.” Descartes was an enthusiastic champion of the new, mechanistic science.
At first glance, Descartes’ strategy of assigning minds and bodies to two separate domains of reality may seem like a plausible compromise. However, there are difficult, nagging problems with this solution. Since we are made up of both a mind and a body, how do the two of them coexist? One theory might be that the mind is like a pilot that directs the ship, which is the body. However, Descartes recognizes that this model is not correct. He says that if this picture were correct, when our bodies were wounded we should no more feel pain than a pilot does when his ship is damaged. The problem is that our minds are much more intimately related to our bodies this. The two seem to mutually influence one another. If I go without sleep, or take cold medicine, or am physically uncomfortable, my mind doesn’t work very effectively. Similarly, I can understand how one physical object can move another physical object. But how does my mind move my body, and how can my body affect my mind? In other words, how is it possible for a spiritual substance and physical substance to interact? The mind has no gears or muscles or chemicals by which to move other things or to be moved. Descartes has created quite a problem for his metaphysics.
He has so radically separated the mind and body that it is not clear how they work together as effectively as they do.
At this point the Cartesian compromise seems to break down. By separating mental substances and physical substances, he neatly placed religion, the human person, and freedom in one compartment, and science, mechanism and determinism in another compartment, where they would not interfere with one another’s domain. Thus, while science can explain the process of digestion in my body, it cannot explain mental events such as my decision to join a church, for example. However, because the interplay of the mind and body is so obvious to our ordinary experience, Descartes had to introduce his theory of interactionism (William, 238). The most notable is epiphenomenalism, which posits a one-way causal relationship: the body affects the mind, causing mental events, but the mind does not affect the body. Mental events are like the babbling of rocks, the exhaust from a car’s engine, or the smoke from train’s chimneys; they are effects of physical processes, (but do not themselves cause motion in the water, the car, or the train (Louis Pojman, 261).
Descartes thought he could pinpoint the place in the brain where the interaction between mind and brain took place: “The part of the body in which the soul exercises its function immediately is in nowise the heart, nor the whole of the brain, but merely the most inward of all its parts, to wit, a certain very small gland which is situated in the middle of its substance.” This gland, the seat of the mind, is the pineal gland. It functions as the intermediary that transmits the effects of the mind to the brain and the effects of the brain to the mind. This was Descartes’ theory of the classic expression of dualist interactionism (Louis Pojman, 263).
The problem is, however, if our minds can influence the physical world through our bodies, then much in the physical world cannot be explained by mechanistic science. The universe is not a self-sufficient clocklike mechanism after all. Yet if the physical forces affecting the body can cause mental events, then our mental life and behavior are, to a large degree, products of the physical environment. In this picture, Descartes’ revolutionary ideas could well be just the inevitable outcome of the purposeless, neurochemical events in this brain. Because interactionism carries with it so many problems, many Cartesians (like Arnold Geulincx and his position of parallelism as well as Nicolas Malebranche and his position of occasionalism) found it necessary to deny it (William Lawhead, 237 – 240).
THE MIND-BODY PROBLEM OF ALFRED N. WHITEHEAD
Whitehead offers a distinctive solution to the classic mind-body problem. Previously, the main options were dualism, materialism, and idealism: the mind and body were viewed as two completely different substances (Descartes), or the mind was reduced to bodily motions (Hobbes), or physical bodies were reduced to mental ideas (Berkeley). In Whitehead’s view, however, there are neither pure mental substances nor pure physical substances. These are abstractions from the more fundamental reality, which is the series of actual occasions, each of which is a continuum having a mental pole and a physical pole. No actual entity is devoid of either pole; thought their relative importance differs in different actual entities. Thus, an actual entity is essentially dipolar, with its physical and mental poles; and even the physical world cannot be properly understood without reference to its other side, which is the complex of mental operations.
In other words, in each part of reality there is that aspect (the physical pole) that tends to conform to the patterns of its immediate past is passive, and causally determined. There is also that aspect (the mental pole) that is creative, active, and self determining. In complex organisms such as humans, the mental pole predominates. This allows us to creatively and subjectively respond to our causal influences, giving us the capacity to respond to a wider range of possibilities and thereby producing greater amounts of diversity. If the mental and the physical are two poles of the same continuum, then nature is not divided into separate compartments (mind, matter, organic, inorganic), but is a unified reality (William, 493 – 494).
Lawhead, William F. The Voyage of Discovery: A Historical Introduction to Philosophy, 2nd ed. USA: Wadsworth Group, 2002.
Pojman, Louis P. Introduction to Philosophy: Classical and Contemporary Readings, 3rd ed. New York: Oxford University Press, 2004.