In this paper the basic tenets of and well as motivations for Cartesian Dualism will be outlined in some detail, after which the problems of mind/body interaction which arise from such a view will be considered. Accordingly, we will explore some of the ways in which some philosophers have attempted to avoid these problems while retaining a dualistic metaphysics. In the end it will become clear why it is that none of these attempts have met with any significant amount of success.
The best way to understand Cartesian Dualism is to avoid any attempt to treat the content of Descartes’ position and the methods by which he reached such content as distinct subjects of inquiry. Indeed, in outlining the path which Descartes burned to reach his dualistic position we will be able to see where it is that Descartes commits the linguistic errors which Gilbert Ryle would later accuse him of committing. In other words, we will intentionally fail to draw a line between the content and motivation of Cartesian Dualism in order to better see both of these subjects as well as the problems which we will also be addressing in a clearer light.
The context in which Descartes found himself was one in which skepticism was fairly widespread, and he saw himself as rebuilding the entire philosophical enterprise from the ground up in a manner which would be immune to such attacks on the dignity of human knowledge. In order to build a philosophical system which would actually be completely immune to skepticism, he forced himself to adopt the strongest form of skepticism which he could conjure, a form of hyperbolic doubt in which everything which could be logically doubted would be. Thus, the very existence of the material world, including his physical body could be and therefore was doubted, for it was logically possible that these things were in fact mere illusions. It was in such a state of hyperbolic doubt that he realized that even if everything which is fed to us through our senses was actually nothing more than a pure fiction, the very fact that he could be mistaken or deceived in such served as proof that ‘he’ as a thinking thing capable of being deceived must, as a matter of logic, exist. Thus, he concluded, “I think, therefore I am.”
It should be remembered, however, that the “I” which does such thinking is not the physical body at all, for it was still possible that even though “he” existed as a thinking thing, his body along with the rest of his sensory input was still an illusion. Thus we see that it is his method of hyperbolic doubt which has led him to draw a line between the logically indubitable existence of his mind as a thinking thing and the merely possible existence of his body as an external, extended thing. We can also see, however, the nature of this division between the body and the mind, for it is merely one of epistemic possibility rather than one of metaphysical necessity or probability of any kind. While it is possible to doubt anything and everything regarding the external world, including the nature and very existence of our bodies, when it comes to the realm of the mind, certainty reigns. While I only believe that I am now typing at a computer, I am absolutely certain that I believe that I am now typing at a computer, a Cartesian would now argue.
A second, and in all likelihood more influential reason for the widespread acceptance of Cartesian Dualism is that it matched up very well with what people had been told about the nature of the mind/soul and the body by religion. Indeed, it is in this context that we should remember Descartes’ second argument against skepticism which basically followed St. Anselm’s Ontological Argument for the existence of God, an a priori argument which made God’s existence logically necessary, and proceeded to argue that since God is necessarily good that He would not allow us to be radically deceived in our interaction with the material and external world. It was from the combination of both his first argument (I think, therefore I am) and his second argument that Descartes arrived at his criterion for truth: if something is known clearly and distinctly, then it must be true for we are primarily and above all thinking things and God is not a deceiver.
We are now in a position to fully articulate the nature of both the mind as well as the body according to Cartesian Dualism, for in so doing we will see the extraordinarily similarities which can be found between Descartes’ view of the mind/body and that of Ethical Monotheism. The mind is without extension in spatial terms and therefore exists nowhere in particular and it is thinking in its nature. Elsewhere, he describes it as being indivisible and free from deterministic constraints. We have also seen that the mental realm is the realm of epistemic certainty. The body, on the other hand, has extension in space and therefore a particular position. It is indefinitely divisible, is non-thinking in its nature and is therefore fully subject to deterministic causes. Such a view is in near-perfect harmony with the view of an immortal soul which transcends the dissolution of its temporary embodiment.
Nevertheless, it is Descartes’ logical argument for the mind/body distinction, rather than its religious motivations which shall primarily concern us. At this point we can turn to Descartes’ Sixth Meditation from his Meditations of First Philosophy:
“First, I know that everything which I clearly and distinctly understand is capable of being created by God so as to correspond exactly with my understanding. Hence, the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct, since they are capable of being separated, at least by God… Thus, simply by knowing that I exist and seeing at the same time that absolutely nothing else belongs to my nature or essence except that I am a thinking thing. It is true that I may have (or, to anticipate, that I certainly have) a body that is very closely joined to me. But nevertheless, on the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing. And accordingly, it is certain that I am really distinct from my body, and can exist without it.”
While the skeptic cannot logically deny the existence of the mind and the certainties contained therein, without Descartes’ appeal to God’s goodness (a weak appeal we must all admit) the skeptic can indeed doubt that he has a body. Following this point, Descartes argues that since he can himself clearly and distinctly imagine his or another person’s mind without a body (we all can imagine and occasionally come in contact with bodies without minds), then it must be that the mind can in fact be disembodied. Since we can only imagine with clarity and distinction that which must be possible, then it is a surety that God can create the situation which we clearly and distinctly imagine.
Here, however, is where Descartes is being a little careless in his use of the term ‘possible’, for simply allowing that something is logically possible in some metaphysically possible world does not necessarily mean that it is actually possible in this world in which we currently find ourselves. Indeed, at this point we can appeal to Gottlob Frege’s example of the Morning and Evening Stars. It is quite easy to imagine with clarity and distinction one of the stars existing without the other, this fact does not change that fact that such is actually impossible in the world in which we now find ourselves for the two stars are actually one and the same planet. Logical (epistemic) separability does not entail an actual (metaphysical) distinction.
Thus we see the main problem which any form of Dualism faces, namely that it is under-motivated by reason, not to mention by empirical evidence as well. Other questions and problems arise as well: How is it that an essentially conscious and thinking thing can cease to be conscious and thinking in the case of sleep? Animals seem to have minds of some kind as well; do they have souls as Descartes argues that human do? Since Descartes’ arguments for and appeal to God’s existence are unconvincing, how can I know anything about the outside world? How can I know that other minds exist? If the mind is free while the body is determined, are we as embodied minds free or determined in our actions? And the most famous of problems, how do the two substances, mental and material, interact with one another?
Descartes’ response to this final question is what has been called Interactionism: the mind can interact with the body and the body can interact with the mind by way of mental events causing physical events and vice versa. For example, I will my arm to move by simply thinking so, and it, a material object moves. A person pricks this same arm of mine with a needle and it causes the mental event ‘pain.’ There are, however, two problems with such a solution to the mind/body interaction problem: First, the idea of immaterial substances influencing and causing changes in physical substances seems to violate the conservation which is observed in motion and energy, as posited by Newton a couple of generations after Descartes. The second problem is that not only does there seem to be no evidence which would suggest such an interaction between substances, the physical events in the brain seem to leave no room for causation by way of mental events, as the Dualist would see them.
Other responses to the question of interaction have been suggested, though they all seem to have the appearance of being desperate attempts at salvaging an otherwise sterile theory (Dualism). Take the case of Epiphenomenalism, wherein physical events cause mental events, but not vice versa. The problem with this response is that it ignores the fact that our minds seem to influence our bodies just as much as the latter seem to influence the former. Indeed, the ability for our minds to influence our bodies by the exercise of freewill seems to be of even more importance than is the ability for physical events to cause mental events. If Epiphenomenalism is true, then life for a conscious being is not at all interactive, but is instead more like watching a very engaging movie over which “we” have no control whatsoever. Not only is this view less than inspiring by way of motivation, it seems to be positively contrary to our everyday experience.
Two other attempts have been made to address the problem of interaction by an appeal to God (the all-purpose life-preserver for bad ideas). The first attempt came from Leibniz in the form of Parallelism: neither mental nor physical event cause each other, but instead both sets of events run exactly parallel to each other, as designed by God. In such a case, our minds would seem to be without any causal knowledge of the physical events which our body is passing through, and to be honest one wonders what the purpose of our bodies would even be in such a case. One is also left to wonder what the point of freewill in the mental realm would be if it necessarily parallels the mechanistic world of matter.
The other attempt to salvage Dualism by an even more direct appeal to God was in the form of Malebranche’s Occassionalism: mind and body do not interact, but God arranges events from one realm to be parallel to events of the other. Again, serious question arise concerning the nature and extent of man’s freewill in such a divinely predetermined system, not to mention deistic concerns regarding particular intervention of God’s part in the course of nature. We could suggest that God is able to influence either the mental or the physical realm in order to maintain the parallel between the two, but this would seem to collapse any difference that there might have been between Parallelism and the straight forward Interactionism which Descartes espoused.
In conclusion, let us review the main objections which Cartesian Dualism has been unable to overcome. The first is Descartes’ error of conflating epistemic separability with metaphysical distinction, an error which leaves his mind/body separation rationally under-motivated. The second is the relatively recent finding that not only does the brain seem capable of generating mental events without any help from an additional metaphysical substance, it in fact seems to leave no room for such help at all, leaving the theory empirically under-motivated. The third problem is that despite serious and sustained efforts to the contrary, the theory has not been able to account for the way in which the mind is able to causally influence the body as well as vice versa, making the theory itself seem relatively vacuous as to theoretical content of any kind. It is not without good reason that most theoreticians have today abandoned Cartesian Dualism.
