Descartes,
Rene (1596-1650):
French philosopher and mathematician. Descartes' unique ambition was not to
add a contribution...but to reconstruct the whole of philosophy anew.
"...those who are seeking the strict way of truth should not trouble themselves about any object concerning which they can not have a certainty equal to arithmetical or geometrical demonstration."
A Dictionary Of Philosophy. Second edition. (Pan Books 1984).
Rene Descartes' Dualism
Rene Descartes is widely regarded as the originator of modern philosophy. He also laid the foundations for modern science. But despite his innovatory ideas about the physical world, he never doubted that conscious minds exist on a separate, non-physical level. Descartes was a dualist. He thought that there are two separate but interacting realms, the mental and the material.
Matter in Motion
Descartes' view of the material world was itself very austere, quite different from previous views, and indeed from much subsequent thinking. He assumed that the material realm contains nothing but matter in motion, and that all action is by contact.
Colours, sounds, smells and so on, are not really in the objects themselves, but are impressions produced in us by the action of material particles on our sense organs.
Mind Separate from Matter
Descartes did not take reality to be exhausted by matter in motion. In partial compensation for the austerity of his material world, Descartes also postulated a separate realm of mind. This other realm was populated by thoughts and emotions, pleasures and pains. These conscious elements had none of the spatial characteristics of matter - namely, size, shape and motion. Descartes took it that mind and matter could interact, despite their radical differences. Material causes can produce mental effects, as when you sit on a pin and so feel mental pain. And mental causes can produce material effects, as when your mental pain causes you to jump up again.
The Pineal Gland
Descartes thought that mind and matter interact in the pineal gland. This is a pea-sized organ in the human brain, situated beneath the corpus callosum, whose function is still not fully understood. It is also the only symmetrical organ in the brain without a left and right counterpart.
Introducing Consciousness. David Papineau and Howard Selina. (Icon Books, 2000). Pages 26 - 29.