Descartes

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by A. C. Grayling


  The question of a happy life was not an idle matter for Elizabeth. Because of her father's famous defeat at the Battle of the White Mountain, her family was poor, and dependent on the charity of royal relatives. She had given up the idea of marriage, preferring a life of study; but even if this had not been so, the behaviour of two of her brothers, Edward and Philip, made it harder for her to contemplate a conventional marriage, whether within or outside what was in effect a widely extended single European royal family. (Another brother, Rupert, married the daughter of an English knight, and went on to become Duke of Cumberland and First Lord of the Admiralty in the British government.)

  Edward converted to Roman Catholicism in order to marry Anne of Gonzaga, daughter of the Duke of Mantua. Elizabeth was deeply wounded by what she saw as his apostasy, and bewailed it in her correspondence with Descartes, seeming to ignore the fact that he was himself a Catholic. Descartes, in kindly and irenic fashion, replied that God had many ways of drawing souls to himself.

  Philip's crime was of a quite different order. It was he who arranged the assassination of one Monsieur L'Espinay (some accounts say he publicly stabbed and killed L'Espinay himself), in anger at the latter's bragging that he had had an affair with his sister Princess Louisa of Bohemia. Philip was obliged to flee; he joined the army of the King of Spain.

  In the resulting family tribulations, Elizabeth and her mother fell out because the Queen thought Elizabeth had encouraged Philip's misadventure. This, as noted earlier, is why Elizabeth was sent away to live with her dreary cousins at the Brandenburg court in Berlin. But the life of a boarded-out poor relation could not hold her forever. In 1667, seventeen years after Descartes' death, she entered a Protestant convent at Herford in Westphalia, eventually becoming its abbess—a position of considerable responsibility, given that in the convent's domains were 7,000 people working its farms, vineyards, mills and factories. Most notably, under Elizabeth's rule the convent became a place of refuge for people of different religions, who found shelter there from persecution.

  Descartes had not been wrong to see something special in Princess Elizabeth of the Palatine, and their friendship does both of them credit. She died in 1680, aged sixty-four; she had met Descartes when she was twenty-eight. It is hard not to see something of his influence in her life, which was, at the very least, consistent with the tenets Descartes advanced in their correspondence on Seneca.

  Descartes' Principles of Philosophy was intended to be a textbook of Cartesian science for use in schools—especially, he hoped, Jesuit schools. He started it in 1641 and it was ready for the printer in the early summer of 1644. It summarised the basics of his philosophy— the sceptical starting point, the certainty of one's own existence, the mind-body distinction, and the goodness of God which guarantees truth when we think aright—and then proceeds to set out his cosmology and mechanics. There is good reason to think that he also intended to include a section on physiology and a section on psychology. A short unfinished essay later posthumously published as A Description of the Human Body, written in the winter of 1647-48, and The Passions of the Soul, written for Princess Elizabeth, might conceivably be Descartes' late efforts to supply these respective omitted portions of the Principles, or at least to cover the ground there left undiscussed. But as for the main parts of the Principles as published, there is nothing in it which is not already in Descartes' previous works, including Le Monde. Gaukroger remarks that it could in fact be regarded as a rewriting of Le Monde, using the Meditations as a better metaphysical basis than was available for the original treatise.16 The main differences between the Principles and Descartes' previous work lie in arrangement; he was trying to make his case as perspicuous and well ordered as he could. Another feature is that he here tries to win over those wedded to traditional Aristotelian philosophy by using some of their terminology in explaining the new conceptions of physics he was introducing, such as force, motion, and rest. The manoeuvre fails; it simply made some of his opponents complain, as already noted, that he did not mean by their words what they meant—and in this they were of course right.

  Central to Descartes' physics is the notion of the "vortices." In the second half of the seventeenth century and subsequently, when Cartesian science was being hotly debated, it was not the metaphysics of the Meditations and the opening section of the Principles which attracted attention, but his theory of vortices. And it was this theory that Newton refuted at the end of Book II of his Principia, preparatory to setting out his own view of how the motion of bodies occurs "in free space without vortices."17

  In Descartes' view, the universe is a plenum of matter in different states—there is no vacuum, no emptiness: space and matter are the same thing. For anything to move, therefore, something else has to move, and Descartes argued that the working of this principle in the universe meant that there would be indefinitely many local swirls or vortices of matter in different degrees of coarseness or fluidity, the matter at the centre of each vortex moving more slowly than the matter on its outer margins. Because of the character of the matter that constitutes the centre of a vortex—it forms as fluid round bodies, Descartes says—-the centres of vortices are suns, and their pushing action is "what we may take as light." The sun, stars and planets are made of various particles of matter, and are carried along in the vortices—the earth itself does not move, being without innate motion, but it is transported around the sun by the great fluid vortex in which it floats.

  Descartes' cosmology is thus an essentially Copernican universe regarded as a plenum, in which motion occurs in the vortices according to his theory of mechanics. His mechanics, summarily put, uses only the notions of size, speed, and rest or motion. Rest and motion are states of bodies which depend upon the mechanical impulse upon them of other bodies. There are three types of matter in the vortices: firstly aether, consisting of very fine fast-moving particles that form the sun and stars; secondly, tiny, smooth spherical particles which Descartes called "celestial matter"; and lastly, larger irregular particles that aggregate to form planets and comets.

  Historians of science point out that although Descartes' theory looks like a clever way of having a Copernican cake and eating it—the earth goes round the sun, but it does not move, for it is carried sedentarily along by a vortex—its main impulse was his adherence to the principle that there is no vacuum. Descartes might be said to have done as nature did, and abhorred the vacuum. In this he was wrong, as the subsequent development of science shows; but it had two very productive consequences. The first relates to his theory of vision, which is that seeing results from pressure on the eye by the universal fluid. The sun, for example, was the centre of a vortex, and its outward pressure on the universal fluid instantaneously translated into pressure on any eye directed towards it. (John Gribbin points out that Newton exposed the fallacy in this theory by noting that if vision were caused by pressure in this fashion, then anyone could see in the dark by running fast enough. Gribbin gives Descartes his answer: no-one can run fast enough to see in the dark.18) The idea of light as waves emanating from a source, like ripples emanating from a stone thrown into a pond, was however explored later in the century by Christiaan Huygens, the brilliant son of Descartes' friend.

  Secondly, the theory of vortices was the starting point for developments in physics later in the century, not least Newton's, who arrived at his own theory of gravitation by rejecting Descartes' account. Since Newton's theory involved accepting action at a distance, contrary to the apparently more sensible view held by Descartes, the contest between the Cartesians and Newtonians was for a time fierce. But Newton's rejection of Descartes' vortex theory was not just right but well-founded. He showed that it conflicted with Kepler's third law, the "Harmonic Law," which relates the time it takes for a planet to orbit the sun to its mean distance from the sun; the law states that the closest planets move at the greatest speeds and have the shortest orbital periods, which is the reverse of what Descartes said. And Newton also showed that unless t
here was a constant input of energy at the centre of each vortex, vortices could not sustain themselves in being.

  After many years' absence from the land of his birth, Descartes at long last found it necessary to return, at least for a visit. He had left France at the end of 1628; his father had died in 1640, and there were matters of inheritance and property to be attended to. He had written to Huygens shortly after his father's death to say that he was going to have to visit France to deal with family matters. But he did not go then, and kept putting it off, presumably until he could delay no longer.

  Accordingly, with what degree of reluctance we do not know, Descartes took ship for France in May 1644 and remained there for a whole six months, mainly in Paris though with a visit to his brother and half-brother, in Rennes and Nantes respectively, to discuss the matters of family inheritances. In Paris he stayed in the rue des Ecouffes with his friend Claude Picot, a priest who managed Descartes' money affairs in France and who was—to boot— preparing to translate the Principles of Philosophy into French. The two of them went to Blois to visit Florimond Debeaune, who had given Descartes' mathematics such a warm reception, and to Tours to visit other friends. And he renewed personal acquaintance with a number of his oldest friends, Mydorge and Mersenne chief among them, who proved as useful as ever, this time by re-introducing him to the two men—mentioned earlier in these pages, but only now entering into deeper personal acquaintance with Descartes—who were destined to play major roles in the remainder of his life and in the future of his reputation: the brothers-in-law Pierre Chanut and Claude Clerselier.

  Chanut was a career diplomat and an amateur philosopher who had helped his friend Mersenne conduct experiments on air pressure, but who—when confronted with the great Descartes— disavowed any scientific expertise, saying that it was moral philosophy rather than natural philosophy that most interested him. Nevertheless Descartes and he took to one another immediately, and Chanut sought every opportunity to advance Descartes' interests. He was almost certainly one of those who worked to get Descartes a pension from the French crown during the next few years, and when Chanut was appointed ambassador to the court of Queen Christina of Sweden in 1646 he sang the praises of Descartes to such an extent that the Queen initiated a correspondence with the philosopher, and later conceived a desire to have him at her court. That was how it came to pass that Descartes ended his life in the Queen's northern fastness, after just one dark winter in her company.

  Clerselier recommended himself to Descartes instantly by the fact that, when they met, he was in the midst of translating into French the "Objections and Replies" appended to the Meditations. As mentioned already, Clerselier became Descartes' indefatigable champion, protector and, after his death, executor and editor, looking after the letters and manuscripts he left behind, publishing the unpublished works and fragments, and furnishing the earliest biographers with details of Descartes' life as he saw it. Baillet claimed that Descartes regarded his friendship with Clerselier as one of the greatest pieces of good fortune he had ever had, and that he "revealed to him the most intimate secrets of his life."19 Whether or not this latter is true, Descartes certainly welcomed the new friendships, and they both indeed proved of immense importance.

  Paris, Blois, and friends constituted the pleasure part of Descartes' visit; but they were not enough to make him think of remaining in France permanently. In a letter to Princess Elizabeth written from Paris in July 1644 he said, "Although there are many people here whom I honour and esteem, I have not yet seen anything to keep me here."20 The business part involved visiting his brother Pierre in Rennes, and his half-brother Joachim in Nantes. He left Paris to travel in their direction just a few days after writing the above words to Elizabeth. His encounters with them cannot have been all tension and haggling, for in the baptismal register at Nantes on 9 September 1644 Descartes signed as godfather for a new nephew named Rene. But in a letter to Picot written some years later, in 1648, he painted what was certainly a truer picture: "Concerning my brother's complaint, it seems to me very unjust. I said nothing in Poitou except that I have not charged him to act on my behalf in my affairs. And that if he attempts to do something in my name or as though it comes from me, I will disavow it."

  When he returned to the Netherlands in November 1644 Descartes was exhausted, and to make matters worse he found not only that his controversy with Voetius was reaching a climax, but that someone who was supposed to be a follower, none other than Henry Regius, was bringing his views into disrepute by publishing nonsensical versions of them. In a letter to Pollot he wrote, "Since my journey to France I have aged twenty years, to the extent that it is now a greater effort for me to go to the Hague than it used to be to travel to Rome. It is not that I am sick, thank God, but I feel weak and more than ever I need comfort and rest."21 Nevertheless his letters to Elizabeth continued in the usual vein, intimate and cheerful; this was the period in which he was writing to her about Seneca, and sending her mathematical puzzles to solve (which she successfully did) as a way of introducing her to his Geomefry.

  Despite the debilitations induced by his 1644 visit to Paris, Descartes returned there in 1647 for another visit, not for as long as in 1644 but long enough—four months—to meet the atomist Pierre Gassendi, the Leviathan author Thomas Hobbes, and the young Blaise Pascal, who was not well disposed to Descartes then or later, being of the camp of Roberval and Fermat. Descartes was, however, curious to meet Pascal, about whom he had heard much.

  The meeting with Gassendi and Hobbes took place at a specially arranged dinner, the intention of which was to reconcile Descartes with them, for they had been sharply critical of his Meditations in the "Objections" he had, through Mersenne, invited them to write. Their objections had annoyed him—as all disagreement invariably did—and he told Mersenne that he thought Hobbes was using the opportunity of criticising the Meditations as a boost to his own reputation. Mersenne and Clerselier were at the dinner with Descartes and Hobbes, but Gassendi could not come because he was sick in bed at home; so when the dinner was over the whole party went to Gassendi's house to wish him well.

  Pascal was a prodigy, who at the age of sixteen had written an essay on conic sections that Descartes could not but admit showed genius; so the prospect of meeting the young man was irresistible. By then Pascal was twenty-one. Descartes had two encounters with him. During the first of them Pascal was in bed with a fever and, moreover, Roberval was present, which annoyed Descartes. Pascal showed Descartes the calculating machine he had made—the first ever computer, based on the technology of knitting machines—and when Descartes rose to leave, having a lunch appointment to keep, Roberval went with him; they got into the coach Descartes had hired, and argued volubly with one another as it rumbled off down the street.

  This first meeting was recorded by Pascal's sister Jacqueline, together with the way it ended:"Monsieur Descartes took [Roberval] away with him in a grand coach, where the two of them were all alone, insulting each other, but somewhat louder than here."22

  At the second meeting between Descartes and Pascal, which took place the next morning, they were able to talk without interruption, and Descartes suggested to the younger man an experiment to determine the issue between his theory of the plenum and Evangelista Torricelli's vacuum-invoking theory of atmospheric pressure. Pascal carried out the experiment in the following year with his brother-in-law, famously carrying glass tubes of mercury up a mountain in Auvergne called Puy de Dome to do so.

  Mydorge died while Descartes was in Paris, and he saw less of Mersenne, who was ill. But he was in the French capital for a particular reason; there were suggestions afoot among some of his friends that the Court might be prevailed upon to award him a pension in the king's name, or some other remunerative recognition for his eminence in the intellectual world. King Louis XIV was still a boy, and the government was in the hands of a regent—Louis' mother, Anne of Austria—and the chief minister Cardinal Mazarin; so it was one or both of these latter two who ha
d been prevailed on to think of the award. The prospect of it was very attractive to Descartes. In ways that suggest that his financial circumstances were no longer what they had been—perhaps his expectations from the 1644 visit to Poitou had not been fully reahsed—he now made a number of additional efforts to pursue either a pension or a sinecure, or at least an office.23 As is the way with royal courts, especially those in straitened circumstances, matters moved slowly, so when Descartes saw that a pension or something similar was not going to materialise straight away, he returned to the Netherlands.

  To avoid travelling back in the autumn Descartes left Paris in September. He took Picot with him for a winter's stay at Egmond-Binnen, his new place of residence, and his last in the Netherlands, for he lived there through all his few remaining years in the country. The task he was reluctantly engaged in was writing a response to the confused version of his ideas that his now former disciple, Henry Regius, was putting about. He had repudiated Regius' independent version of his ideas in the preface to the Principles of Philosophy, but Regius had replied with a pamphlet that Descartes could not ignore, for in it Regius persisted in giving Cartesian science the wrong kind of metaphysical grounding.24 This made Descartes anxious because only his own metaphysics, he thought, could show that his science was consistent with religious orthodoxy.

  But six months later Descartes was packing his bags for Paris again, because the pension scheme seemed to be firming up, together with unspecified but alluring hints of something more—perhaps a title or a distinguished post; and his presence was required to complete the arrangements for it. He had been told that the French Crown was minded to grant him an annual provision of 3,000 livres—six times the interest he was receiving on his property in Poitou—a handsome sum and eminently worth another journey to Paris. He was also excited by the prospect of the unspecified extras, though he said to Chanut in a letter written as he packed, "I do not want an exacting job that would take from me the leisure to cultivate my mind, even though it would give me a great deal of honour and profit."25

 

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