- Flash is required!
René Descartes was born at the end of the 16th century, in 1596. He died in Stockholm in 1650, shortly after arrival there to be the tutor of Queen Christine of Sweden. The 16th century was an age of doubt. First, in religion, many of the old certainties of faith were overturned by the Reformation, so that with the rejection of the authority of the Church, religion became a private and subjective matter. Second, in natural science, the long-standing authority of Aristotle was overthrown as experiments showed much of his physics to be false. In the resulting climate of scepticism there was a need to rebuild the foundations of knowledge. First, Sir Francis Bacon (1561 – 1626) in England tried to make experimental science the model of reliable knowledge. But this did not work because in order to set up an experiment that is going to yield fruitful results you first need ideas. Experiments confirm rather than produce scientific theories. So Descartes, who invented Cartesian co-ordinates and analytical geometry, turned to mathematics as the model of knowledge and philosophy because, as he said, we can all be so sure of “the certainty and self-evidence of its reasoning”.
In order to establish a new foundation of knowledge, Descartes thought it right to take nothing for granted, not to assume anything, but to doubt even those things around us with which we are most familiar. After all, when I think that I am seeing something I may be dreaming it. So he doubted everything which could equally well come before me in my dreams as in my conscious state. I could even doubt the existence of my own body, Descartes thought. But he found that he was still conscious that he existed. He expressed this discovery, which came to him as he sat by a stove in mid-winter in Bavari in 1619, with his famous saying: “I think, therefore I am” (Cogito ergo sum). With these three words Descartes changed the course of philosophy: we could say that up to 1500 philosophy had been objective: it first looked outwards at objectives. This was true even of Plato, whose Ideas were supposed to be objects outside his mind. But with Descartes turning inwards to find what he was conscious of, philosophy became subjective, because he began with introspection. Thus Descartes gave modern philosophy its direction up to the present time and may rightly be called the Father of Modern Philosophy. Another result of Descartes’ first turning to his own mind and consciousness was that metaphysics, about reality, ceased to be the main part of philosophy and was superseded by epistemology. The first question became, What can I know? And, with this question, one can notice a steady tendency towards scepticism in modern philosophy: in Hume, in Kant, in Bertrand Russell. We should note, however, that Descartes did not begin with doubt for the sake of doubting but in order to reconstruct an indubitable foundation of knowledge. I should also add that, for Descartes, to be conscious meant to be conscious of oneself, to be self-conscious. Animals were not conscious, so did not feel pain, in Descartes’ view, because they are not self-conscious like human beings.
The next question for Descartes was, What was this “I” which was conscious of its existence? It could not be a body, because Descartes was doubting the existence of his body and, consequently, supposed that he was unaware of it. It followed that whatever he was, who could say “I am conscious that I exist”, could not be a body and must therefore be something immaterial. So what I am must be my soul: as Descartes wrote in his Discourse on Method, Part IV, “Thus this self (moi), that is to say my soul, by which I am what I am, is entirely distinct from the body”. Descartes concluded that he was a thinking substance, a res cogitans. He divided the world into two kinds of substances: thinking ones (human souls) and extended ones (material bodies). At this point, Descartes’ dualism of body and soul calls for two comments: one about the soul, the other about bodies.
First, if the soul is divided from the body, a question arises whether one attributes sensation to the body or the soul? On the other hand, nothing without a soul can have sensation; on the other, there is no sensation without the bodily organs of the senses. Descartes took the first option and ascribed sensation to the soul, because on his understanding the thoughts (cogitationes) of a thinking substance were not just what we properly call thoughts but included anything we are conscious of, so all our sensations, impressions, mental images, besides ideas and thoughts. He thus introduced an entirely new understanding of the soul: the soul was no longer the principle of life, as it had been for the ancients and medievals, but was now defined by consciousness. We recall that consciousness meant self-consciousness for Descartes and, therefore, he did not think that animals had any kind of soul, not even a sensitive one. When the soul is associated with consciousness rather than life, then it is easily equated just with the mind. But when the soul is first of all the principle of life, then one sees that a human being is a unity of body and soul because all his or her living activities, including movement, sensation and thought, spring from a single source. When, however, the soul is divided from the body and becomes just a mind, then the body is seen as a machine. Thus Descartes’ dualism, which says that who I really am is my soul, has in a paradoxical way led to the opposite view, widespread today and found among surgeons, that a human body is just a piece of machinery. We should remember that Descartes lived in the age that saw the rise of the new physics with Galileo and Newton, which could explain the motion of all bodies in a purely mechanical way.
This brings us, second, to Descartes’ view of all bodies as “extended substances” (res extensae). Being first of all a mathematician, Descartes looked at material bodies in a purely mathematical, or geometrical, way: he was only interested in their measurable quantities (extension, shape and motion). He forgot that bodies are also solid. He eliminated the idea of bodies having a substantial form and, therefore, having natures. Thus Descartes is the original of the modern scientific view of bodies, which sees them all in the same way as a mass of colourless atoms without any difference of nature. A physicist or chemist is rarely interested in a body as a whole but in the structure and motion of the atoms and particles that constitute it. But this is not how bodies first impinge on our senses of sight, hearing and touch.
In conclusion, we can ask whether Descartes’ thought “I think therefore I am” proved as much as he thought. Descartes’ thought that his doubt about the existence of the world came to an end with the certainty of his own existence. But other people have thought that it proved no more than that he existed, that it led into solipsism, the view that I am the only person who exists because I am only conscious of myself. Descartes forgot that he could not have had this thought without his body, because he had conceived it with words which he had learnt from other people by hearing with his ears what they uttered with their mouths. As a student once observed to me, if the world did not exist, Descartes could not have existed. Perhaps it is not so clear that we can think the world is an illusion and our senses are more reliable than Descartes thought.