Descartes’s position on the nature of the self, sometimes referred to as “substance dualism”, is set forth in Meditations on First Philosophy, first published in 1641. Descartes’s view (Rosenthal (ed.), 1991: 21–9) delineates “mind” and “body” as two separate elements. Specifically, he proposes that the mind is a pure intellectual substance, distinct from, and independent of, the physical matter of the body. Moreover, Descartes claims that it is the substance of the mind, not the body, which constitutes the essence of personal identity.
Many people identify with Descartes’s theory in a broader, referential sense; even those who do not consider their understanding of identity to be Cartesian often use a form of substance dualism as a contextual framework to interpret their experiences. However, this framework of interpretation—although ubiquitous—is problematic. An examination of the intellectual genealogy of Descartes’s approach will show that it was compromised from the outset by Descartes’s conflicting theoretical and religious commitments. By building a contextual framework through which to understand the issues in Descartes’s view, these can perhaps be set aside from the core thesis so that its broad common-sense appeal may be better understood.
The Method of Doubt
In keeping with his fascination with empirical certainty, Descartes (Rosenthal (ed.) 1991: 21) set about a thought experiment designed to eliminate all doubtable propositions from his mind. By doubtable, I refer to Descartes’s own definition, “anything which admits of the slightest doubt” (Rosenthal (ed.) 1991: 21). Descartes sought to create a new foundation from which he could establish precise knowledge about the world. Setting this unique criterion to restrict and focus his experimental method, Descartes created what became known as the “Method of Doubt”—a systematic dismissal of any claims that it is at all possible to doubt. Such claims are assumed to be completely false, until proven otherwise.
Descartes leads himself through progressive stages of reduction, with the aid of a theoretical character, an omnipotent, omniscient being, who Descartes pretends is always out to trick and deceive him. Step by step Descartes eliminates everything from his intellectual world, until he feels he is left with a concept that is unassailably certain, about which he could not be deceived. Descartes finally arrives at the belief that the one indubitable fact, from which all else must flow, is that he thinks (Rosenthal (ed.) 1991: 22). From this he deduces that he must also undoubtedly exist.
Descartes’s reasoning runs thus:
1. I doubt everything.
2. To realise doubt, I must think.
3. To be able to think, I must exist.
4. Therefore, I think I must exist.
Having eliminated the concept of all bodies and physical objects as potentially false, Descartes concludes:
“. . . there is a deceiver of supreme power who is deliberately and constantly deceiving me . . . he will never bring it about that I am nothing so long as I think that I am something. . . . I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind. [sic.] (Rosenthal (ed.) 1991: 21)”
Through posing the hypothetical argument that nothing perceived through the senses is to be trusted, that all sensory information has been brought about solely to deceive, Descartes convinces himself that nothing in the external world exists with certainty. Left with only the internal commentary guiding the experiment, Descartes concludes that it is this reflective aspect alone that must be the source of truth. Thus dividing internal and external worlds, the externality of the body from the internal narrative of self, Descartes can only conclude that existence of the latter logically entails existence of the former.
This necessary dichotomy echoes a common way of understanding, defining one concept by virtue of another. There can be no internal without the external, no certainty without doubt. The appeal of Cartesian dualism is instinctive and articulates a common way of understanding the world. It also forms the basis of an individualistic notion of self and a duality at odds with the external world.
Substance dualism in society
Bernard Williams observes (Magee, 2000: 92) that a dualistic view of “subject and object”, “knower and known” is virtually impossible to do without. This may be the case, but it is important to note that this human—and, more specifically, Western—need for duality of experience does not render Descartes’s view on the self infallible or unproblematic. Rather, it informs us of the origins of such a view, and perhaps goes some way to explaining why more than three hundred years after Descartes lived his conceptual framework is still influential.
Williams (Magee, 2000: 92) illustrates the consequence of these theoretical problems, with the remark that such a pronounced demarcation between mind and body is not frequently accepted, despite widespread usage of dualistic concepts in thought. Instead, it is more commonly understood that the “knower” must be embodied—not just an intellectual substance—to actually realise knowledge and experience. In Gilbert Ryle’s critique of Descartes’s position (1949), he summarises this problem by explaining that the dualistic position is constructed upon the idea of contrast between bodies existing in space, and therefore being subject to mechanical law, while the mind exists only in time, leading to the predicament of person having “two collateral histories”: body and mind (Ryle, 1949: 11).
The pursuit of certainty
Descartes was clearly compelled by a fascination with the question of whether anything can be known with complete certainty. This pursuit was one that Descartes believed could thwart the sceptics of his time. Magee (2000: 79) voices the significant point that sceptics were many in Descartes’s time since, following the religious Reformation, numerous assertions were made of methods that would establish religious truth. The climate of religious saturation in which Descartes lived was indeed pivotal to the way he shaped his theory. It also created a weakness in logic that does not stand up well to modern scrutiny, a point to which I will later return.
With his method of doubt, Descartes establishes the existence of an “I”. Next, he proposes to determine exactly what this concept means. It is from this point that Descartes (Rosenthal (ed.) 1991: 21) properly embarks upon an exploration of the concept of self, by returning once again to his original beliefs, and repeating the process of methodological scrutiny to uncover any possible doubt. It is in this further exploration that Descartes defines the mind as a pure substance, bereft of the body, establishing that:
“. . .thought; this alone is inseparable from me. I am, I exist – that is certain. But for how long? For as long as I am thinking. For it could be that were I totally to cease from thinking, I should totally cease to exist. . . . I am then, in the strict sense only a thing that thinks. . . . I am not that structure of limbs which is called a human body.” (Rosenthal (ed.) 1991: 22)
In admitting only what seems to Descartes to be a necessary truth, he has forced himself to omit the body, creating it as separate in form and function from the fundamental essence of self: thought. From this position he cannot logically reduce his concept of self any further. Having arrived at these propositions, Descartes has ostensibly “painted himself into a corner”, believing only in his own thought (Magee, 2000: 84). As such, he is at a difficult place from which to rebuild his knowledge. To do this then, Descartes turns to what he sees as the only other unquestionable truth that is outside of his own certitude of consciousness and can lead to a precise knowledge—the idea of an omnipotent, benevolent (Christian) God.
Begging the question: Descartes’s reliance in God
At this juncture, Descartes’s logic begs the question: how can one doubt in the physical existence of the body, but unquestionably believe in the concept of God? I agree strongly with Magee (2000: 84) that this is very difficult to swallow in the context of contemporary belief. From Descartes’s writing in the sixth meditation (Rosenthal (ed.), 1991: 26), it can be inferred that he feels the need to address a similar question, albeit for different reasons. For having recounted his conclusion of the existence of consciousness from the second meditation, he utilises his knowledge of God to re-introduce the notion of belief in the substance of body as plausible, yet separate from the mind. Claiming that now he has a better understanding of his self and “the author” of his existence, he does not think that “everything should be called into doubt”. Descartes immediately follows this with the justification: “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 of it” (Rosenthal (ed.), 1991: 26).
As Descartes understands the concept of body, God must be capable of creating it, in keeping with his understanding, and therefore it must exist as Descartes sees it. To use God as a justification for the necessity of physical existence in duality with the mind is the weakest principle in Descartes’s theory. Without the sustaining thread of reference to God, Descartes’s view falls apart completely. Here, there is no consistent application of his sceptical methodology, only an ad hoc theological justification. Descartes reasons (Rosenthal (ed.), 1991: 26) that whatever God can create, He is capable of separating, leading to what Descartes sees to be justification for his central tenet—the duality of self:
“It is true that I may have (or, to anticipate, that I certainly have) a body that is very closely joined to me. . . . 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. . . . it is certain that I am really distinct from my body, and can exist without it.” (Rosenthal (ed.), 1991: 26)
Like the reliance Descartes places in the existence of God, it is a leap to assert that thought can continue without a body, simply because a distinction between the nature of the mental and physical realms of existence can be made. Despite popular speculation on the existence of a mind or “soul” after physical death, there is not as yet any evidence upon which to base such a belief. Descartes’s use of God to create a rationale for this idea reveals the paucity of credible arguments for the dualist position.
An irreducible conflict
Throughout his life, Descartes demonstrated his genius for science, alongside his dedication to religious and philosophical thought. As Ryle notes (1949: 18–19), these pursuits gave Descartes conflicting motives in his work—his interest in science led him to support a theory of mechanics, while his commitments to religious and moral belief left him unable to accept the consequences of a mechanical theory of self.
These conflicts led to criticisms such as the one offered by Kolakowski, acknowledging the clash between the mechanical and the spiritual. Descartes did, however, take very seriously the philosophical task of deflecting scepticism. He might be said to have agreed on this point with Hookway (1990: 30), who says of arguments, “if we cannot show where they go wrong, that means that our analysis of knowledge requires revision.”
Thus far I have emphasised contemporary perceptions of problems with the tenets of Descartes’s position of substance dualism, particularly his reliance on God and failure to account for communication between the mind and body. Similar problems with Descartes’s theory also arose in his lifetime, as remarked upon by Williams (Magee, 2000: 93), who comments on the circular nature of Descartes’s justification for his position. Descartes was criticised in his time, as he is now, for the way in which he uses God to validate everything—not only does Descartes employ the concept of God to re-introduce a validity to belief that is external to the thinking self, but also to emphasise belief in “argument in general” (Magee, 2000: 93). Williams observes that, since Descartes uses argument to arrive at this belief in God in the first place, the line of reasoning leads in a circle, using God to justify argument, and argument to justify God. It is only because of Descartes’s clear and distinct apprehension of God’s existence that he makes “any progress from the Cogito at all” (Magee, 2000: 93). It is only Descartes’s confidence that God exists and is not deceptive (unlike the mythical deceiver in the experiment) that offers any confirmation that what he “clearly and distinctly apprehends” is in fact true (Magee, 2000: 93). The self-referential nature of this structure only serves to compound the weaknesses within Descartes’s position and further undermine any recognition of common-sense perception.
The mind-body problem
Prior to concluding I would like to hazard a brief overview of the additional cultural elements, other than religion, that influenced the key tenets of the Cartesian theory of self. I hope this will enable Descartes’s reasoning to be better understood in a contemporary context.
Descartes’s scientific activities very much shaped his thinking in philosophy, particularly since the two disciplines were closely interrelated at that time. During Descartes’s era (1500s–1600s) the human biological sciences were, at best, rudimentary. Now, for example, it is accepted that thought is physically generated by and linked directly to the brain. By contrast, although Descartes acknowledges that the brain does affect the mind (Rosenthal (ed.), 1991: 28), he maintains that it is only a small part of the brain, the “common sense”, that is able to affect any mental change at all. We now know that physical brain alterations correlate directly with altered thought, personality and capacity for physical action, not to mention the many instances in which the physical in turn affects emotional and psychological wellbeing. Due to a lack of testable evidence however, Descartes rejects any biological foundation for mental phenomena. Instead, he emphasises aspects of being that are metaphysical.
This leads ultimately to a view that is unable to satisfactorily explain the interplay between body and mind. Even now, for all the advances of technology and neuroscience, the brain is still somewhat of a mystery. Scientist Christopher Wills (1993: 310) claims that evolution of the human mind has not yet stopped. Whether or not this is the case, a plausible account of the self must at least consider the essential nature of interaction and symbiosis between body and mind—even if this relationship cannot be fully explained.
Having separated human nature so completely, into two very distinct elements, Descartes never sufficiently explains the contingent nature of their reliance upon each other. On this point the substance dualism view is deficient, despite its appeal to the human inability to reconcile the relation of thought to physical action.
Cartesian dualism has been largely out of favour with philosophers for many years and, while there has recently been some renewed interest in the idealist position, it seems unlikely that it could ever be considered wholly plausible without extensive modification. Nonetheless, Descartes’s project has informed many philosophical attempts to understand the nature of personal identity, the empirical certainty of external reality and the way that individuals interact with the world.
That we experience the world from an internalised, subjective perspective is certain. So too is the knowledge that these experiences are enabled and mediated by the body, in particular the brain. Despite this, it remains a challenge for people to reconcile these scientific truths with individual perspective, to fathom the complex interactions that make the mind-body relationship possible. There is a natural duality at the core of personhood, of this, Descartes was correct. It was the extreme to which Descartes was willing to take this separation and his appeal to God to underpin the dualist position that undid his argument.
The primitiveness of the sciences during Descartes’s lifetime and the influence of the church led to an ultimately flawed method of investigation. It is important to understand the context of Descartes’s work so that the flaws in his theory can be understood for what they are, so that the merits of Descartes’s project can be appreciated, rather than dismissed as misguided and anachronistic. There is a definite common-sense appeal inherent in Descartes’s view. Far from being shunned as illogical, this aspect of the dualist approach should be seen as a significant and revealing insight worthy of further investigation.
List of References
Descartes, R. (1991). Selections from Meditations on First Philosophy. In The Nature of Mind, David M. Rosenthal (ed.). Oxford: Oxford University Press.
Hookway, C. (1990). Scepticism. Routledge.
Kenny, A. (1988). The Self. Milwaukee: Marquette University Press.
Kolakowski, L. (1998). God Owes Us Nothing. Chicago & London: Chicago University Press.
Magee, B. (1987). The Great Philosophers. Oxford: Oxford University Press.
Ryle, G. (1949). Descartes’ Myth. In The Concept of Mind. London: Hutchinson.
Wills, C. (1993). The Runaway Brain. New York: Basic Books.