A few obligatory words about the man himself before we go any further. René Descartes was a 17th century philosopher and mathematician, probably most famous for the now-infamous words "cogito, ergo sum" - "I think, therefore I am". He also invented the Cartesian coordinate system, which most of you will have been taught, even if you don't know it (it's the classic x-axis, y-axis thing). In modern analytic philosophy he enjoys a dubious status as both the inspiration and the target of many key arguments. It is a great irony that a tradition which owes so much to Descartes also routinely indoctrinates undergraduates against him.
He did most of his philosophising from the comfort of his bed.
Not that this is necessarily a bad thing. Many of Descartes' arguments are terrible, but the intuitions they appeal to remain strong, and his influence (the "spectre" of my title) can be felt throughout cognitive science and analytic philosophy of mind. Foremost amongst these is the intuition that 'mind' and 'body' must refer to two distinctly separate kinds of things. Descartes thought that this meant they must be composed of two separate substances, one physical and extended, the other insubstantial and non-extended. His cogito argument refers to this distinction - my mind, being a thinking thing, seems to exist independently of (and prior to) any physical world.
Empirical philosophy of mind (and thus cognitive science) tends to reject this dualism. Most philosophers of cognitive science (including myself) are physicalists, committed to there being only one kind of substance in the world. Thus the mind must be made out of the same kind of stuff as the body. Despite this commitment, there remains a tendency to conceive of the mind as something special, somehow autonomous from its physical instantiation. This attitude is sometimes called 'property dualism', 'non-reductive physicalism' , or, by its opponents, 'Cartesian materialism'.
Classical cognitive science, which dates back to around the middle of the last century, was (and still is) enamoured with the idea that the mind is essentially a computer program. As such it made sense to think of the mind as something distinct from the brain, a kind of "software" running on biological "hardware". This intuition is still strong today, particularly amongst those wanting to give an account of mental representation ("pictures" in the mind), or of the apparently inferential structure of cognition. Traditional functionalist accounts of cognition also tend towards a form of Cartesian materialism, as the multiple realisability requirement means that strict type identity between the mind and the brain is not possible. Whilst in many cases the mind (classically speaking) simply is the brain, it's conceivable that it might take some other form, and so the two are not strictly identical.
However, recent (and some not-so-recent) work in embodied cognition argues that the physical body might be more important than classical cognitive science assumes. Examples include John Searle's suggestion that some quality of the neurobiological brain might be essential for consciousness (1980: 78), various enactive approaches to perception (championed by Alva Noë), and the dynamical systems approach that argues that cognition is a continuous process involving the brain, body, and environment. Whilst these approaches differ in many respects, they all agree that the mind cannot be conceived of as distinct or autonomous from the body.
Whilst Daniel Dennett takes an essentially computational and functionalist approach to cognition, he has also warned against the risks of Cartesian materialism - in fact, he invented the term. In Consciousness Explained (1991), he argues that many of our confusions about both consciousness and the self stem from Descartes, and that it is essential that we stop thinking about the mind as a single entity located at some discrete location within the brain. His mentor Gilbert Ryle made a similar point in The Concept of Mind, writing about the "dogma of the ghost in the machine" (1949: 17), the disembodied Cartesian mind that somehow controls the body.
A final Cartesian oddity that I have come across recently is found in the phenomenological work of Jean-Paul Sarte. Despite explicitly rejecting the Cartesian concept of the self, he emphasises a distinction between the "being-in-itself" and the "being-for-itself". The former is something like a physical body, and is all the "being" that a chair or a rock can possess, whilst the latter is what makes us special, the uniquely first-person point of view that we seem to enjoy. IN making this dichotomy he has been accused of resurrecting a kind of Cartesian dualism, in contrast with another famous phenomenologist, Merleau-Ponty, who saw the self as inherently bound up in its relations the the world.
So there you have it, a whistle-stop tour of Cartesian materialism. I'm aware that I've skimmed over a lot of ideas very quickly here, but hopefully it's enough to illustrate the way in which Descartes is still very much exerting an influence, for better or for worse, on contemporary philosophy of mind.
- Boden, M. 1990. The Philosophy of Artifial Intelligence. Oxford: OUP.
- Dennett, D. 1991. Consciousness Explained. Little, Brown and Company.
- Searle, J. 1980. “Minds, Brains, and Programs.” Reprinted in Boden 1990: 67-88.
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