In "The Chain," a chirpy British film comedy from 1984 about moving house, the foreman of a team of movers is taking evening classes in philosophy, and is prone to metaphysical musings while lugging heavy pieces of furniture. On the way to his first job of the day, he recites what he has learned to his workmates: "What Descartes is saying is 'I think, therefore I am.' ''
"Am what?" someone asks.
"Can't just be am. You gotta be am something."
In fact, what Descartes wrote in his "Discours de la Méthode," of 1637, "Je pense, donc je suis" (the Latin rendering, "Cogito, ergo sum," came later), was always a slightly cryptic formulation. That's what helped make it the most famous—and probably the most misunderstood—slogan in philosophy. And "Am what?" remains a good question to ask of Descartes the man, as two new biographies show. His personality remains an enigma. Vituperative, devious, insincere, proud, and unpredictable in his correspondence, he published works that ooze sweet reason and cool logic. Why did this Frenchman choose to spend most of his adult life away from his native country? Why did he repeatedly tell friends that he craved calm and quiet, then constantly pull up stakes and rush elsewhere? (A team of movers would have come in useful.) He did not, in adulthood, enjoy reading the books of others. So what, exactly, was going on in his head during his long mornings of inactivity?
It isn't easy to see Descartes's work the way he saw it—the relationship between science and philosophy has changed too much for that. Despite his current reputation, the man himself seems to have been less interested in metaphysics than in applying algebra to geometry and delving into the innards of cows. He turned to philosophy relatively late in life, and out of fear that the Catholic Church would condemn his science. He would have been surprised at how he is remembered.
Most of all, he would have been aghast at the way in which "I think, therefore I am" has been ripped from its context, inflated into a one-sentence summary of his ideas, and turned into something absurd. The rot set in at the start of the nineteenth century, when Hegel made heavy weather of "I think, therefore I am" and took it to mean that thought and being are fundamentally the same thing. Thus began the myth that modern philosophy is subjective at its roots—a view that was expounded by the late Pope John Paul II, who went so far as to suggest that the origins of Nazism and Communism are somehow linked to Descartes.
The origins of Descartes's slogan are straightforward enough, and it is not easy to see Hitler or Marx prefigured in them. In his "Discourse on Method," which is presented as an intellectual autobiography, Descartes recounts how he aimed to rebuild human knowledge on the firmest foundation. As a first step, to purge himself of error, he tried to cast doubt on as much as possible of what he thought he knew. So he pretended for the sake of argument, as he later put it in his "Meditations on First Philosophy" (1641), that "some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me." Since he could not, at this stage of his inquiries, rule out the existence of such a demon, Descartes reasoned that it was possible to doubt all the evidence of his senses. What he thought he saw, heard, and felt might be a dream somehow procured by the evil deceiver. But then, he says, he realized that there was at least one thing that he could not be wrong about; namely, the proposition that he himself existed. The very act of doubting, of wondering where he might have gone astray, showed that he did exist.
Since the early nineteenth century, Descartes has routinely been called the father of modern philosophy. His attempt at a fresh start for human knowledge, relying on his own reason and casting aside received wisdom, came to typify the Enlightenment project. While his "Discourse" and "Meditations," with their focus on the nature of certainty, the existence of God, and the relation between mind and body, continue to be read by philosophy students, the bulk of his writings, which were on scientific subjects, has been forgotten. In his own day, his physics, cosmology, geometry, and physiology were given at least as much attention. When Molière poked fun at the pretensions of grand Paris ladies, his main target was the fashion for Descartes's astronomy: "I adore his vortexes," Armande coos in "The Learned Ladies," which was first produced in Paris in 1672. "And I his falling worlds," Philamente sighs.
Descartes was one of the precursors of the scientific revolution. Modern applied mathematics is largely based on an invention of his, analytic geometry, which uses algebra to solve practical problems about space and motion. He labored to construct a unified account of nature which would be as all-encompassing as the scholastic system derived from Aristotle but based on the un-Aristotelian "mechanical" principle that physical phenomena are to be explained in terms of contact between moving bodies and the motions and shapes of their parts. In physics and cosmology, Descartes propounded theories that were direct antecedents of Newton's "Principia."
Most of Descartes's scientific work, except for some of his mathematics, has been superseded, which is partly why he is now regarded as a purely abstract thinker. Much of his life, though, was spent in experiments, observations, calculations, and dissections. His explanation of the rainbow, for instance, was a landmark in optics, and almost right. He discovered the law of refraction, which explains why a straight stick can appear bent when partly immersed in water (though this discovery had been made earlier and independently). And Descartes was one of the first to demonstrate in detail that the workings of human bodies could be studied as if they were machines.
In "Descartes: A Biography" (Cambridge; $40), Desmond Clarke, a leading Descartes scholar at the National University of Ireland, Cork, argues that Descartes's philosophy is distorted if it is not seen in the context of his wider scientific enterprise. Descartes certainly played down his own purely philosophical writings. In a letter to his friend Princess Elizabeth of Bohemia, in June, 1643, and again in a conversation with a theology student, Frans Burman, who interviewed him in April, 1648, Descartes warned against paying too much attention to his metaphysics. Read it once, he said, and move on. His "Discourse," with the famous slogan, was published merely as a preface to a collection of treatises on optics, meteorology, and geometry. Clarke reminds us that Descartes's philosophical works were intended to establish credentials for his system of nature, and to make it theologically acceptable. The "Meditations" originally bore the subtitle "in which are demonstrated the existence of God and the immortality of the soul." Indeed, Clarke's most distinctive claim is that Descartes's account of the mind as an immaterial substance—his famous "dualism" of the mental and the physical, sometimes known as the doctrine of "the ghost in the machine"—is at best a provisional theory, aimed at providing support for the Catholic doctrine of the immortality of the soul, and sits uneasily with many other things that he wrote.
Descartes's dualism is certainly not quite what it is often taken to be. In the 1994 best-seller "Descartes' Error: Emotion, Reason and the Human Brain," the neurologist Antonio Damasio reports that Descartes believed in an "abyssal separation between body and mind . . . the separation of the most refined operations of mind from the structure and operation of a biological organism." This is actually the opposite of what Descartes believed. He held that we "experience within ourselves certain . . . things which must not be referred either to the mind alone or to the body alone," and that these arise "from the close and intimate union of our mind with the body." In his best-known writings, Descartes stressed the differences between matter (which occupies space) and thought (which does not). But he also maintained that, in human beings, mind and body are mysteriously and inextricably combined, as he tried to spell out in letters to Princess Elizabeth. (She kept pressing him on the point.) He could not explain how it is that mind and body are united, but he was sure that they were.
Another new biography, "Descartes: The Life and Times of a Genius" (Walker; $26.95), by A. C. Grayling, a prolific British philosopher and newspaper columnist, offers no revisionist interpretation of Descartes's thought but, instead, a highly readable tale with a startling suggestion about his life. Descartes, Grayling reckons, may have been a spy. It's a tempting thought that Descartes was no more the father of modern philosophy than James Bond was a salesman for Universal Exports—that all his geometry and metaphysics was merely a cover for some clandestine derring-do—but Grayling doesn't go quite so far. The possibility he raises is that Descartes did a little intelligence-gathering in the first decade of the Thirty Years' War, as an agent of pro-Hapsburg Jesuits, and that he reported back to the Jesuits about occultist sympathizers. This, Grayling thinks, would help to explain some of his travels and how he paid his way. There is, alas, not a scrap of hard evidence for this theory—Descartes was either no spy or else one of the most successfully secretive there has ever been. This is probably why no historian has mooted it before, and why none is likely to think it worth refuting now.
But is Grayling's spy theory any more fanciful than the late Pope's account? In "Crossing the Threshold of Hope" (1994), John Paul II says that, for Descartes, "only that which corresponds to human thought makes sense. The objective truth of this thought is not as important as the fact that something exists in human consciousness." Later, in "Memory and Identity," published in 2005, John Paul II argues further that the philosophical revolution brought about by Descartes downgraded God and put the mind of man in his place: "according to the logic of cogito, ergo sum, God was reduced to an element within human consciousness." In other words, Descartes inaugurated a shift to a view of the world in which the "I" is the foundation of everything, and a selfish monstrosity rules.
Given that Descartes did not mince his words when attacking his critics—the writings of one French mathematician were "impertinent, ridiculous and despicable"; the rector of the University of Utrecht was "stupid," "malicious," and "incompetent"; the work of Pierre Fermat, the greatest mathematician of his time, was "shit"—one wonders what he would have said about John Paul II. For Descartes repeatedly makes it clear that his own existence (and, indeed, that of the whole world) depends on God, not the other way around. Those who suspect Descartes of rampant subjectivism have confused the style of his reasoning with its substance. Descartes cast his philosophical inquiries in an autobiographical style. He looked within himself. But there was nothing subjective about what he found:
When I consider the fact that I have doubts, or that I am a thing that is incomplete and dependent, then there arises in me a clear and distinct idea of a being who is independent and complete, that is, an idea of God. And from the mere fact that there is such an idea within me, or that I who possess this idea exist, I clearly infer that God also exists, and that every single moment of my entire existence depends on him. . . . And now, from this contemplation of the true God, in whom all the treasures of wisdom and the sciences lie hidden, I think I can see a way forward to the knowledge of other things.
It's true that the informal, meandering style that makes his philosophical works engaging to read can also make their structure elusive. He writes that the certainty of his own existence is the "first principle" of his philosophy. But this just turns out to mean that it is the first certainty that he decided to accept, not that anything else is based upon it. Actually, Descartes infers nothing from his own existence. Instead, he asks how he comes to possess this one certainty, so that he can then find other certainties in the same way. The secret of that certainty is just that it involved "a clear and distinct perception of what I am asserting." Crucially, Descartes then introduces God. He offers several arguments for the existence of God, and, having satisfied himself that there must be a God, he reasons that this God, being good, would not allow His creatures to be seriously deceived, provided that they exercise some restraint and confine their beliefs to what they "clearly and distinctly" perceive to be true. Thus Descartes's system of knowledge depends not on his own existence but on God's.
René Descartes was born into the upper bourgeoisie on March 31, 1596, in a village then called La Haye, in the Loire Valley. Always a secretive man—his motto was Bene vixit, bene qui latuit ("He lives well who is well hidden")—he would not allow his date of birth to be published in his lifetime, for fear that someone might cast his horoscope. His father had hoped that he would follow him into legal practice and provincial officialdom, and marry well. In the event, René disappointed his father's dynastic ambitions, though his older brother, Pierre, delivered the goods, and the family acquired the lowest degree of nobility in 1668. René inherited some farms from his mother's family, and then sold them to help pay for his life as a gentleman scholar. His father said that he was the only son to have disappointed him, because he was "ridiculous enough to have himself bound in calfskin."
Descartes's mother died when he was fourteen months old, and his father entrusted his upbringing to relatives. At the age of ten, René was sent to the recently established Jesuit College of La Flèche. His health was weak, and a kinsman, Father Charlet, who was the rector of the school, managed to secure him special treatment. He had his own room and was allowed to laze in bed in the mornings, which became a lifelong habit. The other boys had to rise at 5 A.M.; Descartes apparently did not rouse himself until Mass at ten.
In 1614, he left the Jesuits to study law at Poitiers, graduating and rejoining his family two years later. How he then occupied himself is a mystery, but in 1618 he began his travels, aiming, as he later said, to "roam about in the world, trying to be a spectator rather than an actor in all the comedies that are played out there." He decided to enroll as a gentleman (i.e., unpaid) soldier in the army of Prince Maurice of Nassau, outside Breda, on the truce lines between the north and the south of the Netherlands. Descartes was rather bored, contenting himself with some painting, military architecture, and learning Flemish. It was thanks to an apparently chance meeting in the street in Breda that his intellectual career began to take shape.
On November 10, 1618, Descartes was reading a mathematical puzzle posted in Flemish on a billboard, and asked a passerby, Isaac Beeckman, to translate it into Latin. Seven years older than Descartes, Beeckman had just completed his medical degree while earning his living as an engineer and candlemaker. He was interested in applying mathematics to mechanics, explaining regularities in physical phenomena in terms of the behavior of their minute constituents—an approach to science which began to flourish in Holland in the late sixteenth century. The two men struck up a close friendship, and Descartes became, in effect, Beeckman's apprentice, using his mathematical skills (which were by all accounts superior to Beeckman's) to solve problems set by his master. It is unclear whether or not Beeckman was one of the catalysts for the revelation that Descartes claims to have had at the age of twenty-three, a year to the day after his first meeting with him. That was when he went to bed after a day's excited contemplation in which he discovered the "foundations of a marvellous science," and had a series of vivid dreams that changed his life. Possibly, it was a nervous breakdown rather than the intellectual breakthrough that Descartes later made it out to be. Either way, within a few years he seems to have been set on a life of learning, focussing on the natural sciences and mathematics.
The night of dreams took place in Neuburg, as Descartes was journeying to rejoin the army of Maximilian of Bavaria, with whom he had enlisted after leaving Prince Maurice's ranks. In the next decade, he travelled in Germany, France, the Netherlands, and Italy; did some of his most important work in geometry and optics; and started writing a treatise on the scientific method, which he never finished. In late 1628, he moved to the United Provinces (the northern, and Protestant, part of the Netherlands) and spent all but six months of the rest of his life there, living at twenty-four or more addresses in twenty years. Nobody has managed to shed much light on why he was so restless. (Grayling thinks that his spying days were over by then.) But it is lucky that he was, since he otherwise might not have written so many letters. What emerges from his correspondence is that Descartes was difficult, wildly ambitious, and hungry for fame. He rarely seems to have been a soul at peace.
At about the time of his move to the United Provinces, Descartes began work on "Le Monde," a pair of treatises giving a mechanistic approach to physics, cosmology, and physiology. While in Amsterdam, around 1630, he visited butchers' shops every day to get carcasses for dissection. (Grayling mistakenly credits Descartes with the first known observation of a conditioned reflex, in 1630. In fact, Descartes made no observation and was just guessing: "I reckon that if you whipped a dog five or six times to the sound of a violin, it would begin to howl and run away as soon as it heard that music again." Contrary to Grayling's claim, there is no reason to think that he ever actually whipped a dog, though he may on another occasion have dissected a live one.)
In 1633, Descartes's original scientific work pretty much came to an end, when, in July, Galileo was condemned by the Inquisition in Rome, and his recently published "Dialogue Concerning the Two Chief World Systems" was burned. Descartes immediately decided to lay aside "Le Monde." Although little harm could have come to him in the United Provinces (or, probably, in France, where there was no Inquisition, and considerable sympathy for Galileo), Descartes wanted to avoid arguments with theologians.
The main objection to Galileo's work was ostensibly its heliocentrism. The Church still maintained that the sun went around the earth, not vice versa. After all, the Psalms say that the earth cannot be moved; Genesis says that the earth was created before the sun; and Joshua told the sun and the moon to stand still while the children of Israel attacked the Amorites, which (it was argued) he would not have done if the sun was already still. Descartes knew that the earth did move. He wrote in November to his old friend Marin Mersenne that if this view were false then so, too, were the whole foundations of his system.
It was at this point that Descartes turned to the metaphysics and philosophizing about knowledge for which he is now remembered. He also turned to sex, some speculate for the first time. His daughter, Francine, was born in 1635 to Helena Jans, a maid in a house in Amsterdam where Descartes stayed. Francine died of scarlet fever five years later. She seems to have spent some time with Descartes, who pretended that she was his niece. A bizarre myth began to circulate in the eighteenth century that Descartes was accompanied on his later travels by a life-size mechanical doll that he called Francine. This seems to have been a gibe at the mechanistic view of nature which his philosophical works sought to underpin.
In the course of his "Meditations," he argued that the properties of physical objects that he could "clearly and distinctly" understand were measurable dimensions in space, geometric shape, duration, and motion, but that, "as for all the rest, including light and colours, sounds, smells, tastes, heat and cold and the other tactile qualities, I think of these only in a very confused and obscure way." In other words, he was claiming that the only physical facts of which knowledge can be guaranteed by recourse to God, who would not deceive us about things that we can "clearly and distinctly" grasp, are precisely the elements of his mechanistic system of nature. Descartes thereby provided, or so he thought, a justification that would appeal to the Church for his view that all natural phenomena can be explained by the principles of geometry and pure mathematics. He could not find any support for those views in the Psalms, Genesis, or Joshua, but he could at least bring God into the picture.
It did him no good. Descartes not only failed to win over the theologians of his day but forever weakened his philosophy in trying to do so. The flimsiest parts of his "Discourse" and "Meditations," as generations of undergraduates learn, are his proofs of the existence of God, and his argument that God would not deceive us. (Mersenne noted that God sometimes misled people in the Bible, so divine deception wasn't easily ruled out.) Several of Descartes's works were placed on the Index of forbidden books by the Catholic Church in 1663. The Church worried that his account of matter might be inconsistent with the Eucharist, and that he did not make the mind sufficiently independent of the body.
In France, men of letters and society ladies warmed to Descartes long before universities did. But in 1720 he achieved part of his ambition, when some of his books were put in the curriculum of the University of Paris. They did not, however, supplant Aristotle, as Descartes had always wanted, but were set for study alongside him.
Descartes died, of pneumonia, in Stockholm in 1650, at the age of fifty-three, having unwisely procured an invitation from Queen Christina of Sweden, and then even more unwisely accepted it. In the coldest Swedish winter in sixty years, he found himself obliged to stand bare-headed at five in the morning in Christina's library to give her philosophy lessons. It was a cruel change for a man who was not exactly a morning person. Four years later, the Queen abdicated and converted to Catholicism, prompted, she wrote, by Descartes's teachings.
He was buried in Sweden under a simple wooden monument that was allowed to rot. Seventeen years later, his remains were exhumed and taken on a six-month journey to France, except for his right forefinger, which the French Ambassador to Sweden was allowed to keep, and his head, which was removed by a captain in the Swedish guards. In France, his body was exhumed and reburied three more times before coming to rest in a former Benedictine monastery in Saint-Germain-des-Près. The Musée de l'Homme, in the Palais de Chaillot, near the Eiffel Tower, claims to have Descartes's skull, but the claim is weak. It seems that the great dualist's head is still missing.