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6.2: Dualism

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    Now we shall examine dualism. It is the first of the options on the mind body problem. It is the most popular conception, it appears as the most obvious answer to the problem and it is the source of the problem all at the same time!

    Dualism, Cartesian Interactionist - the view that:

    1. the mental and the material comprise two different classes of substance and;
    2. both can have causal effects on the other.


    Plato thought that the soul could and would exist apart from the body and would exist after the death of the body. He offered a "proof" for this position and was the first to do so in writing that we have any evidence of doing so. He offered several different proofs, or arguments, none of which are convincing today. They are held to be specious arguments or terribly flawed and unconvincing. He held that humans were composed of bodies and souls but the soul was more important and immortal. His arguments used premises which we question today. For example, Plato thought that he could conclude that the soul could exist independent of the body because it acted independently from the body when it engaged in pure thought. This is no longer accepted as true since it is equally evident today that without a physical brain thought appears unlikely to occur. Plato thought that the only way to explain how people come to know things is that they are remembering the knowledge implanted in their souls when the souls were in the realm of pure thought and eternal forms before entering into the body after which they forgot as they became confused by physical emotions an feelings and limited experiences through the senses. This is no longer accepted as the best explanation of how people come to have knowledge. None the less, Plato is credited with being the first human to attempt to set out any sort of a proof that humans had souls and that they survived the death of the body and that they were immortal. He offered these arguments in the dialogue he wrote titled the Phaedo.

    Rene Descartes

    Descartes also believed that the soul existed prior to and separate from the body (see Meditation II of Meditations on First Philosophy) and so was immortal. In his view all of reality consisted of two very different substances: matter/physical and spirit/non-physical. The physical was what would be extended in time and space and the non-physical would not be so characterized. For Descartes, the soul of a human exists prior to and separate from the body. His proof consisted of argumentation that has been seriously criticized and rejected. He thought that if he could in some form demonstrate that humans can prove that they exist without first proving that they have physical bodies then that would prove that they did not need a physical body in order to exist. He thought that his famous claim that "I think therefore I am" established not just that he existed, but that he existed without a body as a "thinking thing." A "thinking thing" is a thing that thinks and by that would be included: imagining, conceiving, hoping, dreaming, desiring, fearing, conjecturing, reasoning, remembering, and more. For him a "thinking thing" needed no physical parts to do what it does. Modern science has established that there is no evidence of humans that are without a physical body and its brain. There is no evidence that thought is possible without a brain. There is much evidence that what has been associated with Descartes' "thinking thing" is now explained solely in terms of the brain and how the brain is physically structured and the functioning of the brain.

    Cartesian Skepticism

    Variations of Dualism

    1. Interactionism - minds and bodies exist and interact in some way
    2. Epiphenomenalism - body acts on mind but minds do not act on bodies
    3. Double aspect theory - there is one substance with two aspects (mind/body)
    4. Parallelism - minds and bodies exist in separate dimensions and are coordinate
      1. Pre-established harmony - minds and bodies are set in motion and coordinated from the beginning of time by a deity that creates the universe
      2. Occasionalism - on the occasion of the mind making a decision the body is moved by the creator (deity) to do whatever the mind has decided to make the body do.

    Interactionism; History and Critics


    1. René Descartes
    2. The 17th Century: Reaction to the Dualism of Mind and Body
    3. The 18th Century: Mind, Matter, and Monism
    4. The 19th Century: Mind and Brain
    5. Mind, Brain, and Adaptation: the Localization of Cerebral Function
    6. Trance and Trauma: Functional Nervous Disorders and the Subconscious Mind


    1. The 17th and 18th Centuries: The Epistemology of Mind
    2. The 19th Century: The Epistemology of the Nervous System
    3. Mind, Brain, and the Experimental Psychology of Consciousness


    1. Mind, Body, and Culture: American Psychology before William James
    2. Biological Consciousness and the Experience of the Transcendent: William James and American Functional Psychology

    So with dualism comes a number of problems. The most conspicuous and troublesome are:

    1. Where does the interaction take place?
    2. How does the interaction take place?
    3. The idea of the mental causing the physical to act appears to violate the principle of the conservation of energy
    4. The idea of two realities appears to violate Ockam’s Razor, the principle of simplicity, which holds that if there is no need to postulate additional entities one should avoid doing so.

    Here are some of the dualists’ responses to these points and objections to them or criticisms of them.

    1. Non-physical entities do not have spatial properties, so there is no need to locate them in physical space.
    2. Such entities have their own metaphysical laws to follow.
      1. God, mind, spirit, and souls all operate within that realm.

    Objection: what are those laws and how do they account for the results in the physical universe?

    1. Dualists claim that: substances do not need to be similar in order to interact.
    2. There is also ample evidence that they do interact.


    1. It was the dualists who established that the two substances were so different that they could not interact.
      1. The source of the problem is the dualist distinctions of the two different substances.
    2. The evidence for interaction could be explained in terms of brain actions alone. The obviousness of one’s causing one’s body to move by an act of the mind is not as obvious as it seems.
    3. The mind may not add energy to a closed system, it may be simply redirecting the energy already present.

    Objection: how does the mind affect the redirection if the mind is not itself made of energy or matter?

    1. Dualists claim there is a compelling reason to hold that there are two substances and not just one.
    2. They claim it is needed to account for all phenomena of human experience including consciousness.

    Objection: The monists claim that it is not necessary at all and that they have a satisfactory explanation of such phenomena.

    Substance Dualism Part 1 & 2

    The other variations on mind body dualism

    1. Interactionism - minds and bodies exist and interact in some way (covered above)
    2. Epiphenomenalism - body acts on mind but minds do not act on bodies

    What is the stream of consciousness?

    Double Aspect Theory: there is one substance with two aspects (mind/body)

    Spinoza on Mind and Body Interaction

    Baruch Spinoza and Double-Aspect Theory

    Born in Amsterdam, Spinoza spent his life as a lens grinder. A Jew who had been expelled from the synagogue for unorthodoxy, he maintained few ties to either Dutch or Jewish contemporaries and published little during his lifetime. The metaphysical masterpiece, de ethica, was first published in 1677, in order to retain the notion of God as the one true cause without sacrificing the idea of causality as operative in both the mental and the physical spheres. Spinoza abandoned Descartes' two-substance view in favor of what has come to be called double-aspect theory. Double-aspect theories are based on the notion that the mental and the physical are simply different aspects of one and the same substance. For Spinoza, that single substance was God. While agreeing with Descartes that the world of consciousness and that of extension are qualitatively separate, Spinoza rejected the Cartesian view that consciousness and extension are attributes of two finite substances in favor of the notion that they are attributes of only one infinite substance. That substance, God, is the universal essence or nature of everything that exists. The direct implication of Spinoza's view is that while mental occurrences can determine only other mental occurrences and physical motions can determine only other physical motions, mind and body nonetheless exist in pre-established coordination, since the same divine essence forms the connections within both classes and cannot be self-contradictory. In the latter half of the 19th century, dual-aspect theories underwent a revival.

    Occasionalism and Nicolas Malebranche

    Occasionalism is the idea that on the occasion of the mind making a decision the body is moved by the creator (deity) to do whatever the mind has decided to make the body do. If the natural world is radically divided into the mental and the physical such that the physical is extended in space.

    The mental is not, and if the nature of causality is such that causes and effects must have a necessary connection and be of a similar type, then mind/body interactionism of the Cartesian sort is obviously untenable. Perhaps the first important attempt to deal with this contradiction in Descartes was known as occasionalism. The work of Nicolas Malebranche (1638-1715) was probably the most influential purveyor of occasionalism.

    Malebranche was born in Paris and was educated at the Collège de la Marche and the Sorbonne, where he began to read Descartes in 1664. A decade later, he published De la Recherche de la Vérité in which he argued that both of Descartes' substances, mind and body, are causally ineffective. God is the one and only true cause. Not only is there no influence of mind on body or of body on mind, there is no causality operative at all except insofar as god, the one true cause, intervenes to produce the regularities that occur in experience. Thus, for example, when a person wills to move a finger, which serves as the occasion for God to move the finger; when an object suddenly appears in a person's field of view, which serves as the occasion for God to produce a visual perception in the person's mind.

    Occasionalism and Nintendo


    • This theory would make God an accomplice in every evil act.
    • The two aspects of the one substance are either illusory or if real then there is the dualism issue once again as to how they are to interact.

    Parallelism (Psychophysical)

    1. Minds and bodies exist in separate dimensions and are coordinated
    2. Pre-established harmony; minds and bodies are set in motion and coordinated from the beginning of time by a deity that creates the universe.

    Still another alternative to Cartesian Interactionism is that of Psychophysical Parallelism. This view retains both the dualism of mind and body and the notion of a regular correlation between mental and physical events, but avoids any assumption of causal mind/body connection, direct or indirect. Psychophysical Parallelism eschews Interactionism on the grounds that events as totally dissimilar as those of mind and body could not possibly affect one another. It also rejects Occasionalism and Dual-Aspect Theory on the grounds that no third entity, whatever that might be, could be responsible for such vastly different effects. Parallelists simply accept the fact that every mental event is correlated with a physical event in such a way that when one occurs, so too does the other.

    Parallelism in this form is usually traced to Gottfried Wilhelm Leibniz (1646-1716). Historian, mathematician, philosopher, scientist, and diplomat, Leibniz was born and received most of his education in Leipzig. In 1676, after a period at Mainz and four years at Paris. He later went to Hanover, where he spent the remainder of his life. An inveterate correspondent, contributor to scholarly journals, and creator of manuscripts, much of Leibniz' most important work was embodied in letters, published in article form, or left unpublished at his death.

    Leibniz presented the famous articulation of Psychophysical Parallelism in which he adapted an occasionalist metaphor to support the view that soul and body exist in a pre-established harmony. Comparing soul and body to two clocks that agree perfectly, Leibniz argued that there are only three possible sources for this agreement.

    1. It may occur through mutual influence (interactionism), through the efforts of a skilled workman who regulates the clocks and keeps them in accord (occasionalism),
    2. Or by virtue of the fact that they have been so constructed from the outset that their future harmony is assured (parallelism)
    3. Or by the notion that mind and body exist in a harmony that has been pre-established by God from the moment of creation.

    Leibniz rejects interactionism because it is impossible to conceive of material particles passing from one substance to the other and occasionalism as invoking the intervention of a deus ex machina in a natural series of events. All that remains is parallelism - the notion that mind and body exist in a harmony that has been pre-established by God from the moment of creation.

    Objection: This theory seriously challenges notions of human freedom.


    Each attempt to defend the dualism of mind and body meets with objections. If you want to take the dualist position that we have both a physical and non-physical mind that position needs to be defended with reasoning and evidence and not merely made to rest on faith based claim. In Philosophy it must be supported by reasoning and evidence. There must be both the exposition of the problem with the dualist claim and its solution. The dualist position creates the mind body problem. What is needed is a response to all the criticisms of the dualist position? Remember it is the one position that creates the problem. A dualist needs to account for all the evidence that disproves dualism and then needs to bridge the gap between the non-physical and the physical and solve the problem of interaction.

    Dualists also need to be aware that there is no claim about what a non-physical mind does that has not been demonstrated to be the result of brain activity and functioning. Neuroscience discredits the claim of a non-physical mind. What evidence is offered by contemporary dualists of the existence of a non-physical mind?

    Mind refers to the aspects of intellect and consciousness manifested as combinations of thought, perception, memory, emotion, will and imagination, including all of the brain's conscious and unconscious cognitive processes. "Mind" is often used to refer especially to the thought processes of reason. Subjectively, mind manifests itself as a stream of consciousness. If this is the definition of mind then reflexes, controlled responses, survival instincts are not part of the mind, but actually a part of the brain.

    Philosophical Application

    Suppose you are playing a game of pool with Jose Sharco. Jose is more skilled than you, and he is already working on the eight ball while you still have most of your balls on the table. Suddenly Jose stops and put down his cue. He closes his eyes and stands very still. At first you think that Jose is simply concentrating before he attempts to sink the eight ball. But after several minutes, you become irritated and ask him: “Hey, Jose, what are you doing? You’re supposed to take your shot.” Jose responds, “I’m in the process of taking my shot. I have decided to sink this last ball with my mind. Just give me a couple of minutes to focus all of my mental energies on the ball.”

    You respond, “Well Jose, you can stand there and think about sinking the eight ball until you’re blue in your face, but I can tell you one thing for sure: It’s not going go anywhere. In order to move the eight ball you need another physical object like a stick or a hand. Minds are not sufficient to move matter.”

    What if Jose doesn’t accept your explanation? What would you tell him then?

    Thought Experiment: Zombies

    Chalmers claims that it’s possible for him to have a zombie twin, a creature physiologically and functionally identical to him, but lacking any conscious experience.

    (1) Does this possibility show that consciousness is nonphysical? Why or why not?

    (2) Could a zombie (a creature with no mental states) do everything that a normal human being can do? Why or why not?


    Vocabulary Quizlet 6.2

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