The Problem of Cartesian Dualism

By Susan J. Fleck.  November, 1992.

Descartes' Method

Descartes had two ultimate goals which he was sure would literally change the course of mankind and alter the whole body of knowledge taught in the Schools.  First, he wanted to establish a new method to have the means to discover and know the one truth about each thing or problem being examined.  To this goal he applied mathematical principles which he felt offered absolute certainty in resolving problems.  Second, because current 'philosophy' offered no assured foundations, and since the rest of the sciences were built upon 'shifting sands', he needed to establish some basic principles:  He felt this was the most important thing in the world.  In fundamental ways, Descartes did change the course of mankind - for philosophic debate and for very practical scientific results.  This paper will discuss - 1)  the background  and a brief description of the fundamental principles Descartes discovered;  2) emphasize his views on the relationship of the mind to the body;  3) the one major flaw he left unresolved in dealing with the mind / body;  4) how the philosophers Spinoza, Leibniz and Hume  were concerned with this problem;   5)  and how they dealt with it in the context of their metaphysical or epistemological frameworks.   Note - because of the length of this paper being limited to only ten pages, instead of ten thousand, I will not be able to explore much of the metaphysics and epistemology of these great philosophers; but instead, will concentrate on the mind / body relationship (challenge enough for only ten pages!).

Descartes  had been educated in scholasticism, but he  lived during the 'high Renaissance' when secularization was rampant and there was much tension where the doctrines which he believed were constantly being challenged.  Skepticism was a movement at this time reacting to the rapidly advancing scientific world.  So with all of these competing viewpoints, Descartes felt under extreme pressure to find a firm foundation.  This perhaps explains why he would throw out virtually all his former 'ideas' and 'knowledge' to discover a new epistemology and metaphysics.

His method for coming to any certain conclusions consisted of the following rules, stated simply:  1) Doubt any evidence that is not absolutely clear to one's reason.  Avoid pre-conceived ideas and hasty conclusions.  2) Divide a problem into as many parts as possible, to make it manageable to solve.  3) Start with the simplest parts and work gradually, in an orderly way, to the more complex.  4) Check your work to ensure nothing is omitted.  Descartes was sure this mathematical process of deductive reasoning should be able to be applied to the more lofty of life's great problems.  Note:  'Intuitive' reasoning is also important in his Method, as Descartes felt that man had the capacity to distinguish the true from the false - to see evidence 'clearly and distinctly' through his innate common sense.  Also note that he had become a skeptic, something he deplores, by doubting everything.   He did not attack each individual belief, but the very foundation of all of those beliefs.  So he set out to solve the huge problem of the nature of the Universe.


He removed his skepticism with his first proposition that "I am or I exist is necessarily true every time I conceive it or I utter it."  He arrived at this from the following kind of dialogue:   "Am I so tied to a body and its senses that without them I can not exist?  Having convinced myself that there is not body, am I not non-existent?  But, if I did convince myself of anything, then I must have existed!  But suppose there is this evil demon..   could he deceive me about my own existence?  NO - if he deceives me, then undoubtedly I exist."   Doubting was a key concept with proving both that he existed and that God existed.  Descartes' famous "I think, therefore I am" proposition detaches the act of doubting from reference to anything external to itself.  Doubting is thinking, and one cannot perceive that one thinks without being certain that one exists.  He could have pretended that he had no body, but not that he did not exist.  But if he ceased to think, he would have had no reason to believe he existed.  He therefore concluded that he existed and his whole existence was his mind (soul) which did not depend on any external material thing.  Even if the body were not, the mind would not cease to be all that it is. 

Pure Consciousness

So he had discovered what he was - a thinking thing that could not be doubted away - a conscious intellect; pure consciousness with no spatial location properties (i.e. nothing bodily).   He had driven a wedge between the concepts of mind and body - a wedge from which philosophy has not yet recovered.  Space does not permit an exploration of Decartes propositions about God and nature, but he did come back to believe in matter, in God, in God's preserving action through His established perfect physical laws,  and in animals which were like perfect machines.  But man, whose primary existence is thinking, has a mind / soul which therefore could not have 'evolved' from matter, but must have been created expressly and therefore is not lodged in the body.  The mind is closely linked to the body (somehow), but entirely independent of it, and therefore not subject to die with it.  Since Descartes could not clearly see any other means of destruction, he concluded that the soul is immortal.

Thus, Descartes had arrived at a philosophy of dualism, which held that God created two kinds of fundamental reality.  One was thinking substance, the mind / soul -  a single, indivisible, spiritual substance - with subjective experience; and the other - objective substance - everything outside of the mind.  Consciousness constitutes the very nature of the mind:  It must be present in order for the mind to exist.  Extension in length, breadth, and depth is the very nature of body.  This was his basic metaphysics.  Most people have a view that we have both a mind and a body which are 'completely things' even though they are ordinarily tied together (somehow) in life, and that after death a mind may continue to exist.  Most of us want to believe that we are more than just simply a physical substance.  I.e. that we do have a soul, which makes us different from a stool or a pig.


Let us look at the implications of this Cartesian Dualism.  1)  Human bodies are in space and are subject to all the forces of mechanical laws that govern all other bodies.  Minds, however, are not in space, nor are they subject to mechanical laws.  2)  The operations of the bodily life is as much a public affair as with trees, stars, etc.  (in principle).  But the operations / workings of one's mind are private from  external observers.  3)  There is no direct causal connection between two minds as there may be between two bodies.  However, how I affect you must be mediated by the body.  4) Minds are composed of different 'stuff' (substance); bodies are composed of physical matter.

Descartes had four theses about his dualism:  1) The mind is not affected by the whole of the body, but only by the brain.  He came to this conclusion from his scientific studies and observing the 'phantom limb' phenomenon.  2) The relationship between mind and body is causal in character, and it really works - which is evidence of God's Goodness!  This means that a particular thought causes a mind state change, which causes a change to your brain.  When your brain gets the message that your body just got hurt, your mental state changes.  The pain is not felt by the brain, but is felt by the mind.  The brain and the mind is a two-way street - CAUSAL LAW.  3)  There is a one to one correspondence between mental states and brain states.  4)  The mind / brain interaction takes place in the pineal gland.

Pineal Gland: Linkage

With this last thesis, he is trying to solve the fundamental flaw in Cartesian Dualism.  The problem is that we do not have the explanation of the mechanics of the causal interaction between an immaterial, non-extended substance of the mind; and a material, extended substance like the body.   Where does the mind come from, and how does it get so intimately related with your body?  Descartes' view of the soul is said to be like a 'ghost in a machine', but we are not sure how this ghost can control this machine.  If your decision to telephone a friend happens in a totally non-physical mind; how can this decision make you pick up a phone and dial?  How can something non-physical cause something physical to happen?   We think in terms of physical causation such as force, mass, velocity, motion, acceleration, etc.; and in terms of mental causation with belief structures such as desires, goals, feelings, beliefs and intentions.  But we cannot cross these two boundaries and claim, for example, that "well, the chalk just wanted to break (when hurled against the blackboard)".  Or you would never talk about the 'velocity of my frustration'.  So, if the mind and body are two completely different and separate entities, then Descartes had introduced a problem from which the world has not yet recovered.

Descartes defined "what I am" as a  thinking thing - a thing which doubts, understands, affirms, wills, and which also imagines and feels - all presumably without a body.  But here he could not accept his own dualism, for he admited that "nature also teaches me by these sensations of pain, hunger, thirst, etc., that I am not lodged in my body as a pilot in a vessel, but that I am very closely united to it, and, so to speak, so intermingled with it that I seem to compose with it one whole."    Recognizing this serious flaw, he attempted to solve it with his theory of the pineal gland - where messages arrive at the soul.  But this is nonsense since the soul is not located in any place - so how could a message arrive at it when it is immaterial?  If you think of yourself as just a mental consciousness and your brain is something different, then how could you understand someone 'tapping' your brain causing a different state in your mind?

The Occasionalists

The first philosophers after Descartes that tried to fix the Cartesian Dualism  problem were dualists called Occasionalists.  Their view is that God is the one physical potency that could work in both realms.  Divine Intervention is a concept we can all understand - where God occasions things to happen.  God, being all-knowing, observes you slamming your hand on a table; there is some physical stuff going on; then God intervenes and causes you to feel pain.  He also 'reads your mind' and causes you to act upon your thoughts.  This is certainly consistent with the western Judeo-Christian paradigm of a God that can cause things to happen, (miracles) and also with some peoples' concepts of predestination.  (Although I would think of God as a rather busy being if he had to cause every event and monitor every thought of every human!! - my little pineal gland has a hard time comprehending such a being.)   This kind of cause-effect answer presents other problems with which the philosopher / theologian must then struggle with:  1) God as the initiator of even evil;  2)  The concept of freedom of choice;   and   3) God's relationship with us.   Besides, it would be somewhat intellectually lazy  to just accept this answer, before exploring other alternatives.  There are negative implications when we replace the pineal gland with God, so let us look at other explanations.

Spinoza: Substance, Attributes, Modes

Spinoza wondered "how a philosopher of Descartes' calibre.., who had developed such a rigid method of reasoning; ... . that such a philosopher would assume a hypotheses more occult than any occult quality.  What concept does he have... I wished that he would have explained this union."   Spinoza's objection went beyond puzzlement, however, because he had profound differences in his fundamental beliefs about the universe.  Let us compare their primary metaphysical structures.  Descartes believed   1) in independent kinds of Substances -  thought (mind) and extension (physical, non-mind);   2)  that Attributes are dependent;  and 3) that a Mode is a way of being an attribute.  An example of this is a scarlet-red  shirt:  Shirt = substance;  red = attribute;  scarlet = mode.

Spinoza's metaphysics has the same 'inventory' of categories but with much different meanings.  With him, there is only one Substance which must be infinite and eternal (God).  Therefore minds and bodies can not be different substances.  Then what are they?  God's power is expressed as an infinite series of Modes and these are all causally related in a single natural system.  Minds and bodies are modes which are dependent on God/nature.  They are not qualities, like scarlet, but they are ways of being the one substance and are dependent - you can not tell what they are 'out of context'.   For example (Bob's rather graphic example), a pimple is a pimple only if it is on something, e.g. a face.  The pimple is a mode of the face, and the face is a face - pimples and all.  This is not intuitive to our way of thinking and our use of these words.  We normally think of a pimple as being an attribute of a face (as in 'she has nice attributes!).  But since we are dealing with God (and Spinoza) here, there must be an infinite series of ways in which the infinite series of modes is expressed.  These ways are called attributes, and for some reason, we (mere humans) are able to grasp only two of these attributes:  Thought and Extension.  When we perceive modes through the attribute of thought, these are known as ideas;  when perceived through the attribute of extension, they are thought of as physical things.   For example, if science were advanced to where neural 'maps' could be made such that one could 'read off' someone's experiences, then a doctor could hook me up and could 'see'  about my headache from the extension of the printout.  He would know about my headache through a different attribute (extension) than I know about my headache (consciousness).

In the context of this paper (which is an extension of my limited thought about Spinoza) the main thing we need to know is what are minds and bodies in Spinoza's paradigm.  They are dependent particulars, but not independent substances like they are for Descartes.    Envision a straight line as being the whole of reality and a man standing on this line.  For Descartes, the line is the ground and the person is independent.  For Spinoza, the man is like a 'bump' on the line  (we are like pimples on God's face - what an analogy!).   He had two premises:   (1) My body is a way the ONE substance has of being (mode); and  (2) What I am is dependent on causal law; it is a result of the active part of nature - the ONE substance.  The first is true of the mind, but we cannot picture it.  The second can not be said of the mind.  Spinoza was motivated to reject Cartesian Dualism because he did not think it was possible to get the mind into the network of causal, scientific theory, unless we physicalize it.  This is why he re-defined the nature of the mind so it would 'fit' this picture, in terms of causal law.  He was the first philosopher to try to fit the mind into nature, and not make it separate from nature.

For Spinoza, nature - the physical universe -  is made up of infinitely many small corpuscles which he calls 'simplest bodies'.  These are either in motion or at rest, depending on what the other simple bodies around them are doing (you can imagine lots of little atoms bouncing off each other).  Our bodies are a composite of many simple small bodies.  Something becomes individualized as Spinoza put it:  "When a number of bodies of the same or different magnitude form close contact with one another through the pressure of other bodies upon them, or if they are moving at the same time or at different rates of speed - so as to preserve an unvarying relation of movement among themselves - these bodies are said to be united with one another and all together to form one body or individual thing - which is distinguished from other things through this union of bodies."  He said that every individual thing strives to maintain its own characteristic internal relations of motion, even as it undergoes changes, and this struggle  for 'self-preservation' is a thing's individual essence.  "Everything insofar as it is in itself, endeavors to persist in its own being.  This endeavor is nothing else but the actual essence of the thing in question."

Spinoza: Parallelism and Propositions

Individual composite bodies are part of larger composite bodies, and so on.  "And if we proceed in this way to infinity, we shall easily conceive that the whole of nature is one individual whose parts, that is all bodies, vary in infinite ways without any change of the whole individual."  Because all things are in a sense 'in' God, Spinoza's philosophy is often called a pantheism.  He was obviously a monist and (not so obviously) a materialist (this is controversial - but, then, what isn't in the field of philosophy!).  This entire complex of physical order is also expressed as  ideas: "The order and connection of ideas is the same as the order and connection of things."    This is known as the Parallelism Doctrine.  Most people think he was solving the Cartesian Dualism problem by denying that there is any interaction between the mind and the body.  They have mistaken this doctrine to mean that Spinoza had a picture of the mind and body like two trains running on separate but parallel paths - as an alternative to dualism.  But that is misleading because these are not two different orders, but rather one order of modes expressed in two different ways - this is a doctrine about substance - the one thing.

Although this doctrine does not answer to the question of Cartesian Dualism like had been believed, in an oblique way it does signify Spinoza's response to this problem.  To see how this is accomplished, we first must examine how he used the word 'idea'.   The normal notion of an idea in philosophy is that it corresponds to an image - it is a representation.  Ideas are in people's heads.   But when we deal with the 'order and connection of ideas', we are not dealing with representational pictures,  but rather with propositions - things being able to be confirmed or denied.  "Bob was born on mars (or somewhere else, definitely out-of-space)!"  This idea has a 'truth' value, and propositions / ideas are true or false independent of human thought.  For anything that is about the universe - for every 'fact' in the universe - there is a corresponding proposition.  These propositions do not allow for any interpretation - they are pure, raw facts only.  You get a 'true' proposition as long as there is a corresponding physical 'stuff'; and you get a false proposition if there is not a corresponding physical thing.  But false propositions are not about anything; therefore, there can be no false propositions in this scenario.   This is a picture about the ONE Substance and is nothing about humans.  So, while causal laws dominate the order and connection of things in the physical realm, propositions dominate the order and connection of things in the idea realm.

So let us begin a series of minor modifications to Spinoza's doctrine to see if it will then 'fit' to what is probably his theory of the relationship of mind and body.  By changing the word ideas, as the above argument lends itself:  "The order and connection of propositions is the same as the order and connection of things."  Remember, we grasp (understand) physical things under the attribute of extension, and these propositions are not 'mental' things - they are not things in someone's head.  The mind is not in this picture yet and the word thought is misleading here.  Spinoza could talk about the attribute of thought, without thinking about any actual mind at this point.   According to Dr. Wachbrit:  "The attribute of thought is a way of grasping the 'one substance' by grasping the logical relations between propositions about the causal history of the physical universe."   But humans think in sentences and sentences express propositions.  So a conclusion from this can be that all of the propositions on the 'thought'-attribute side of this doctrine are possible thoughts

The second modification then is:  "The order and connection of possible thoughts is the same as the order and connection of things."  But in Spinoza's paradigm you can only have true propositions, not just possible thoughts.  So one more minor change:  "The order and connection of true possible thoughts is the same as the order and connection of things."  The third modification considers humans:   "The order and connection of actual thoughts by a finite intellect are the same as the order and connection of certain things expressed as a mode of extension."  Here we move from possible (not considering human beings) thought to actual (needing humans) thoughts.  The order and connection of actual thoughts by a finite intellect are the same as the order and connection of the physical correlates of thought, namely brain / body events.  Therefore, actual thoughts are nothing more than brain / body events.  In this view, mentality has dropped out of the brain / body events, because 'thought' is only telling us various brain states.  I.e. all that is ever going on in us is physical stuff.

So Spinoza solved the Cartesian problem of the relationship between the mind and the body by eliminating one of the substances - mental - and thus eliminating the need for causal interaction between the two.  From this view, it appears that Spinoza was a Materialist, who did not believe in any mental stuff in the world, but that there was only material substance.  His parallel doctrine can be thought of as like two different (perhaps colored) windows through which one can look to grasp reality - the ONE substance.  If you peer through both of these windows you would see the same substance, which is first comprehended under one attribute (the physical extension window) and then under the second attribute (the idea of the physical).   According to Spinoza the ideas that constitutes your mind are the ideas of your body.  Each individual's mind is made up of those of God's ideas that are the ideas of that individual's body.   This is void of any human thought and a very strong claim of determinism.

Leibniz: Idealism and Monads

Although Spinoza interpreted the mental out of the picture, Leibniz did the opposite:  He interpreted the body out of the picture.  If there is only one kind of substance, there is no need to explain how two different things interact.  He believed there is no material stuff - he was an idealist in the sense of being the opposite of a materialist.  Where Spinoza talked about 'simplest bodies' and composites, Leibniz proposed monads and aggregates.  Spinoza's 'stuff' is physical, Leibniz's is non-extended.  So we will now briefly explore Leibniz's monadology and his views of the soul and God as they relate to the mind/body problem.

First, six basics about Leibniz's paradigm of monads:  1)  Monads are simple, extensionless, partless (and heart-less), individual, figureless substances (i.e. non-extended).     2)  There must be 'simples' because there are composites.  3)  They can not be material, because then they could always be divided (could be infinitely divisible - like one of Zeno's famous paradoxes).   4)  They can not be affected by each other:  They have no windows!  5)They are not changed by anything external;  they affect nothing external.  6)  They are not physical atoms with causal interactions between them.  They are more like mental atoms.  (Note:  Leibniz was not an Atomist.)    Up to this point we can understand only what monads are not.  There is also a fundamental problem similar to the problem of Cartesian Dualism:  How can you get a physical 'extension' out of unextended mental substance?  To discover Leibniz's answer to this, let us examine some more positive qualities of monads, since - although the whole paradigm of monads seems utterly crazy - they did work for Leibniz.

Monads are perceptions - but do not think of them as 'little consciousnesses'.     Monads get a lot of perceptions, but most of them are at the unconscious level.  They typically perceive only a small fraction of the universe objectively presented to them - these conscious perceptions are called 'apperceptions'.   (But note, for God, the whole of the universe is objectively present at one time.)   How they perceive is not explained by mechanical causes / laws.   But every monad's perceptions are different from every other monad - this is what distinguishes one from another.  Because we are body-bound, we could never have exactly the same experience at two different times, or as another person.  We will have a different perspective, a different 'angle', a different 'view' on the subject at hand.  So monads perceive the world 'as if' they are in a different space, even though they have no extension.   Since mechanical causes are not relevant, Leibniz made a distinction between monads and a sub-class called 'souls'All monads are mental substances, but not all monads are souls.   A soul is a monad whose perceptions are more distinct than other monads, and are accompanied by memory.  The non-souled monads are somewhat 'dazed'.   With this paradigm up to this point I can construct what I am:   I am an aggregate of monads, one of which is the soul, the 'chief' monad which remembers and perceives more distinctly than all the dazed monads of my body, all of which can perceive the universe.   I am different from a stool because 'I got soul'!

We have examined Leibniz's basic 'stuff' of the universe, monads, and how they relate to human bodies and souls (minds).  Now let us turn to his basic principles, see how they relate to God and monads, and how this all relates to the mind/body problem.  First the Principle of Sufficient ReasonNo fact can be real or existent, no statement true; unless there be sufficient reason why it is so, and not otherwise.  Leibniz extended this principle to God and why our world is the way it is.  Suppose God is ready to create the world and there is an infinite number of possible worlds (picture a deck of cards to choose from).  If you are All Good and All Knowing, as God is thought to be, then you must create the best of all possible worlds.  God is constrained by' Sufficient Reason' and His own nature to do this.  (Note:  This does not mean that He created a most beautiful world in the sense that there is no evil, ugliness, etc.;  rather, that it is the best - metaphysically speaking.)  

When God actualized the universe, he created monads everywhere and they are all different.  God has created the best possible world, which is objectively presented to every monad at all times (but each monad may not be aware of it).   Think about what it would be like if every monad did not perceive the same universe - e.g. I saw a dog, you saw a violin?   But their perceptions are all in harmony.  Even though there are differences in their perceptions, this is just due to differences in their point of view.   This is known as Leibniz's Principle of Pre-Established HarmonyIf it is to any monad as if  'X' is the case; then it is to every monad as if 'X' is the case.  Most of us believe that we perceive our environment - that there is a world out there that affects our senses and we perceive the environment in the same way.  Since Leibniz did not believe that bodies exist independent of monads, he had to explain why we (monads) perceive in the same manner.  This led to the assumptions that God had to create the best of all possible universes - so it would 'function'; and that monads had to be harmonized to perceive. 

So what can we make of all of this?  What would Leibniz have said about this meaning:  "The ball is red."  For him, this means to every monad it is perceptually, consciously or not, as if the ball is red.  This view is a very strong form of the view of objects known as phenomenalism.  Physical objects are not real in the sense that they do not exist independently of perception.  An example of this - rainbows do not exist, except as a 'product' of the perception of light passing through water.  His infinite array of monads agree because of harmony, and they have a total comprehension of their perception.  Every monad perceives everything in the universe at all times, to some degree of consciousness, but from different views.    Bodies are mere phenomena and even all the causal relationships they are in are perceptual phenomena.  Causal Laws are phenomenal.  All the interactions between the monads are mitigated phenomenally.  They (we) perceive relations with other monads, but monads, qua monads, do not have anything to do with other monads.  The bottom line is - monads have no windows - and therefore have no causal relations with one another.

He also abandoned his theory of composite beings, recognizing the problem of explaining how a bunch of non-extended monads could make up a physical aggregate of something.  He did not feel it necessary to have anything outside of souls or monads, and therefore bodies do not exist.  Any interaction that occurs between mind and body is purely perceptual.  We do not need our bodies to explain what is going on when we slap our hand on a table and feel pain / sensation.  Since he made bodies, space they inhabit, causal relationships, and the mind-body interaction all purely perceptual phenomena, therefore there is no real causal relationship between the mind and the body.  And, it is all determined from the very beginning - everything - because God has created the best of all possible worlds (rather extreme determinism)!  This is how Leibniz solved the Cartesian Dualism problem.

Hume: Bundle Dualism

Spinoza got rid of the mind as an answer to this problem we are struggling with, and Leibniz got rid of the body.  Now we come to Hume, who brought both the mind and body back into the picture.  But not in the manner our western, Aristotelian minds would hope for in order to resolve this question once and for all!  In a nutshell (no Freudian slip intended), Hume was a psychological-dualistic empiricist.   Where Descartes got rid of all the senses, Hume claimed that all knowledge comes through your senses.  Hume, like Descartes started out, was a thoroughgoing skeptic.  Like Descartes, he doubted everything, but from a different perspective.  He questioned "Where do we get the IDEA that  'X'  is the case?  What information do we get from our senses that give us the idea?"  If we know where we get the idea, then we can know what is the nature of  'X'.  Hume expounded the basic empiricists' doctrine: "All ideas come from antecedent impressions."  So we need to look at his understanding  of 'ideas' and 'impressions'

With Hume there is a psychological 'inventory' which explains the foundation of his metaphysics.  The basic unit of knowledge is perception.  This is made up of Impressions, Ideas, and Concepts.  Impressions is broken down into two categories - Sensations and Reflections.  Now to define these terms.  Sensations are from direct interaction with physical objects, e.g. heat, cold, touch, hearing, sight, etc.  This category also includes passions, emotions and moral sentiments.   Reflections are the kinds of things that gets called to mind after you have already had an experience.  You have an original experience which causes an original impression, the mind takes a copy such that the next time you are in this 'situation' the mind calls up the memory-impression.  It is a real feeling, and more forceful and vivacious than ideas.  This category also includes attitudes, aversions, and desires.  Ideas are a faint image of an impression.  If you see something, then close your eyes and 'picture' it, this is a faint copy of the 'real' thing.  These are less lively.   Concepts include verbal knowledge.  This involves the meanings of words.   Later empiricists called this analytic truths.  For example, 'a bachelor is an unmarried man'.  You know this without sense perceptions.  Logic and mathematics contain verbal truth.   So there are only three ways in which something can come into someone's mind:  Sense, recall, and imagining former impressions.

With this  epistemological view, Hume launched two attacks against Descartes.   First, he attacked mental substance.  There is no impression that gives rise to the idea of a substance of mind -  no sensation, no reflection, nothing painful, nothing pleasant.  Running through his inventory of how things get into one's mind, there is no account of why or when such an idea comes - or what produces it.  The concept of substance (mental or otherwise) can not come from antecedent sense impressions.  Second, he attacked Descartes' concept of self / ego - that which provides a unity of all experiences.  There were six steps to this attack:  1)  'All ideas arise from [antecedent sense] impressions' (and it must be some one impression that gives rise to every real idea).  2)  'But the self, or person, is not any one impression.'  It is that to which our many different impressions are supposed to have a reference.  E.g. you do not just feel pain, the pain is 'yours'.  3) 'If any impression gives rise to the idea of the self, that impression must continue invariably the same through the whole course of our lives, since the self is supposed to exist in that manner.'   What single conscious impression about yourself stays with you your whole life - i.e. that can define, give rise to the idea of,  YOU?   4) 'But no impression is continuous and invariable.'   We can find impressions of e.g. green, blond hair, etc. introspectively, but how do we find our self in this manner?  5)  'So, the idea of the self can not arise from impression.'   Finally:  6) 'Therefore, there is no such idea.'

If there is not mental substance and there is no ego / self, then what is there?  Hume gave us his idea of the mind:  "The human mind is nothing but a bundle or collection of different perceptions which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement.  The simplicity and identity that others have seen in the mind is an illusion.  There is no simplicity at any one time;  there is no identity at different times."  The name of this theory is BUNDLE DUALISM.  When you get the concept of substance and self out of the picture, there is simply a stream of impressions that you can never grab a hold of, and are they are constantly changing.  The mind lacks the unity that Descartes envisioned.  Per Hume,  it is only due to momentary resemblances of our ideas that there appears to be continuity and resemblance.   As far as the body is concerned, Hume believed in its existence, but offered no proof.  This was no big problem with him.

So there is a mind and a body with Hume's paradigm.  How did he solve the mechanics of the relationship between them?  He did not care about the questions - 'How can we explain this?' or 'How does it work?'  Rather, he wanted to know - 'where do we get the idea about something?'   Hume's view of causation in general is what he called Constant Conjunction.  This means the fact that one event always follows another event, where our mind by custom associates one idea with another.  Descartes' idea that the mind and the body are in causal interaction is compatible with Hume's Constant Conjunction.  But Hume had removed the need for analysis of this causal interaction by changing the question from 'what is the nature of this interaction?' - to - 'where do we get the idea that there is an interaction?'.


So we have come full circle from having defined a major philosophical problem, to stating that this is not a  problem.     Descartes posed a whole new metaphysical paradigm for the universe, but left the mechanical nature of the causal relationship between the mind and the body unexplained.  He attempted to solve this problem by saying that the pineal gland was the mediator.  That was not an acceptable solution.  The Occasionalists tried to fix the flaw without a metaphysical re-categorization by making God the mediator between mind and body who caused all things, mental and physical, to happen.  Spinoza answered the problem with a metaphysical re-categorization by saying everything is ONE substance, it is material, and there is no mind.  Leibniz then went on to show that Spinoza is all wet (phenomenally speaking), because in Leibniz's paradigm there is no body - everything is purely perceptual phenomena.  Spinoza and Leibniz each got rid of one side of the equation, either mind or body, so therefore there would be no causal relationship between the two to explain.  Hume brought both the mind and body back into the universe, but he attacked Descartes' concepts of mental substance and of the self /ego.  Hume was an empiricist and a skeptic with a psychological inventory of concepts which enabled him to substitute for the question - 'what is the nature of this  interaction between the mind and the body?' - this question - 'where do we get the idea that there is an interaction?'  He removed the need for any analysis of this problem.  For now, I think we should join Hume and give this problem a rest so we can 'get a life' - so to speak (wherever we get the idea that we have a life)!

Works Cited

This essay was written as a mid-term essay exam using notes taken in my class:  Philosophy 440: Philosophy of Mind.  California State University, Fullerton.  Fall, 1992.  Instructor: Robert Wachbrit.

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Copyright 2002 by Susan J. Fleck. All rights reserved.