by Will Durant
VI. RENÉ DESCARTES: 1596–1650
First of all, he had a Jesuit education, which has been the starting point and whetstone of French heretics from Descartes through Voltaire to Renan and Anatole France; “In the Temple were forged the hammers which destroyed the Temple.”78
He was born at La Haye in Touraine. His mother died of tuberculosis a few days later; he inherited the disease from her; as an infant he was so pale and weak and coughed so pitifully that the physician offered no hope of saving him. A nurse would not give him up as lost; she gave him the warmth and nourishment of her body. He came back to life, and perhaps for that reason he was called René—Renatus—reborn. His father was a prosperous lawyer, a councilor of the Parlement of Rennes, who at his death left his son an income of six thousand francs per year.
At the age of eight he was entered in the Jesuit College of La Flèche, which, says an ardent freethinker and famous mathematician, “seems to have given him a much better grounding in mathematics than he could have got at most universities at that time.”79 His teachers recognized his physical weakness and mental alertness. They allowed him to remain in bed beyond rising hours and noted that he used the time to devour one book after another. In all his metaphysical wanderings he never lost his admiration for the Jesuits, and in their turn they took his doubts with paternal indulgence.
At seventeen he went to Paris to sow wild oats; he found that he had none to sow, being as yet indifferent to women; but as a devoted mathematician he took to gambling, figuring that he could break the casino bank. He went on to the University of Poitiers, where he received degrees in civil and canon law. Having gained health and strength, he amazed his friends by enlisting in the army of Prince Maurice of Nassau (1618). When the Thirty Years’ War gathered impetus, he joined the forces of Maximilian, Duke of Bavaria; an uncertain tradition pictures him as having taken part in the battle of the White Mountain.
Amid these campaigns, and especially in the long months when winter interrupted slaughter, Descartes continued his studies, especially of mathematics. One day (November 10, 1619), at Neuburg (near Ulm in Bavaria), he escaped the cold by shutting himself up in a “stove” (probably an especially heated room). There, he tells us, he had three visions or dreams, in which he saw flashes of light and heard thunder; it seemed to him that some divine spirit was revealing to him a new philosophy. When he emerged from that “stove” he had (he assures us) formulated analytical geometry, and had conceived the idea of applying the mathematical method to philosophy.80
He returned to France in 1622, arranged his finances, and set out again on travels. He spent almost a year in Italy: went (some say on foot) from Venice to Lore to, paid his tribute to the Virgin, saw Rome in the 1625 jubilee, passed through Florence, did not visit Galileo, and came back to Paris. There and in the countryside he pursued scientific studies. He accompanied the mathematician and military engineer Gérard Desargues to the siege of La Rochelle (1628). Later in that year he moved to Holland; and barring some visits to France for business purposes, he spent nearly all the remainder of his life in the United Provinces.
We do not know why he left France. Possibly, “having shown forth” his “reasons for doubting many things,”81 he feared accusations of heresy; and yet he had many ecclesiastical friends there, like Mersenne and Bérulle. Perhaps he sought to avoid friends as well as enemies, hoping to find in an alien land the social (but not intellectual) isolation in which he could give form to the philosophy that was seething within him. He disliked the bustle and prattle of Paris, but did not mind the busy traffic—soft-pedaled by canals—of Amsterdam; there, “in the crowded throng of a great and very active people,” he says, he could “live as solitary and retired as in deserts the most remote.”82 It may have been to conceal himself still further that he changed his habitat twenty-four times in the next twenty years—from Franeker to Amsterdam to Deventer to Amsterdam to Utrecht to Leiden, but usually near a university or a library. His income allowed him to live comfortably in a small château, with several servants. He avoided marriage, but took a mistress (1634), who bore him a daughter. We are pleased to hear that when this daughter died at the age of five, Descartes wept humanly. We should err if we thought of him as coldly unconcerned with mundane affairs. We shall find him justifying many of the passions that moralists normally condemn. He had some himself, being subject to pride, anger, and vanity.83
It took a proud spirit to dare his scope. Consider what he undertook: mathematics, physics, astronomy, anatomy, physiology, psychology, metaphysics, epistemology, ethics, theology; who would venture today on such a circumnavigation? For this he coveted seclusion, made experiments, equations, diagrams, weighed his chances of escaping or appeasing the Inquisition, and sought to give mathematical method to his philosophy, and philosophical method to his life.
Where should he commence? In the epochal Discours de la méthode,III he announced a first principle that in itself could have brought the world of authority down upon his head; all the more so since the essay was written in readily intelligible French, and in an animated, captivating, firstperson style; here were many revolutions! He would begin, he said, by rejecting all doctrines and dogmas, putting aside all authorities, especially of ille philosophus, the philosopher, Aristotle; he would start with a clean slate and doubt everything—de omnibus dubitandum. “The chief cause of our errors is to be found in the prejudices of our childhood84… principles of which I allowed myself in youth to be persuaded without having inquired into their truth.”85
But if he doubted everything, how could he proceed? In love with mathematics, above all with geometry, which his own genius was transforming, he aspired to find, after his initial and universal doubt, some fact which would be admitted as generally and readily as the axioms of Euclid. “Archimedes, in order that he might draw the terrestrial globe out of its place and transport it elsewhere, demanded that only one point should be fixed and immovable; in the same way I shall have the right to conceive high hopes if I am happy enough to discover one thing only which is certain and indisputable.”86 He hit upon it exultingly: Je pense, donc je suis, Cogito ergo sum, “I think, therefore I am”87—the most famous sentence in philosophy.IV It was intended not as a syllogism but as an immediate and irrefragable experience, the clearest and most distinct idea that we can ever have. Other ideas should be considered “true” in proportion as they approach this primal intuition—this direct perception—in distinctness and clarity. Descartes’ new “method” in philosophy, his novum organum, was to analyze complex conceptions into their constituents until the irreducible elements are simple, clear, distinct ideas, and to show that all such basic ideas can be derived from, or can depend upon, the primary consciousness of a being that it thinks. Conversely, we should try to deduce from this primary perception all the fundamental principles of philosophy.
It was again a revolution in philosophy that Descartes took as his starting point not external objects supposedly known but the conscious self. The Renaissance had rediscovered the individual; Descartes made him the hitching post of his philosophy. “I see clearly that there is nothing which is easier for me to know than my own mind.”89 If we begin with matter and rise through levels of organic life to man, we shall be tempted by the logic of continuity to interpret mind as material. But matter is known to us only through mind; only mind is known directly. Here begins modern idea-lism, not as ideal-ism in an ethical sense, but as a philosophy that starts with the immediate fact of ideas, rather than with things known through ideas. Descartes sets the epistemological theme of modern European philosophy: “No more useful inquiry can be proposed than that which seeks to determine the nature and scope of human knowledge.”90 Now for three centuries philosophy would wonder if the “external world” exists except as idea.
For just as it is difficult to pass from body to mind with any theory that does justice both to the apparently material source and agency of sensations and to the apparently immaterial nature of ideas, so Descartes,
having begun with the self, finds it difficult to pass from mind to things. How does the mind know that the sensations that seem to attest an external world are anything more than its own states? How can it trust the senses, which so often deceive us, or the mental images that are just as vivid when “false” in sleep as when “true” in the day?
To escape from this “solipsistic” prison of the self, Descartes appeals to God, who surely would not make our whole sensory equipment a deception. But when did God come into this system that began so boldly by doubting all received beliefs? Descartes cannot prove the existence of God from evidences of design in the external world, for he has not yet shown the existence of that world. So Descartes evolves God out of the knowing self, very much as Anselm had done in the “ontological proof” six centuries before. I have, he says, a conception of a perfect being, omniscient, omnipotent, necessary, and eternal. But that which exists is more nearly perfect than that which does not; therefore a perfect being must include existence among his attributes. And who could have put that idea into me but God Himself? “It is not possible that… I should have in myself the idea of a God if God did not veritably exist.”91 For if God were a deceiver He would not be perfect. Therefore he does not deceive us when we have clear and distinct ideas, nor when He allows our senses to reveal to us an external world. “I do not see how He could be defended from the accusation of deceit if these ideas were produced by causes other than corporeal objects. Hence we must allow that corporeal things exist.”92 So the gap between mind and matter, subject and object, is marvelously closed, and Descartes, by the help of God, becomes a real-ist. Science itself—our confident belief in a logical, orderly, law-abiding, calculable universe—becomes possible only because God exists and cannot lie.
As we follow Descartes we see the infant Age of Reason recoiling in fear from the hazards of thought and seeking to re-enter the warm womb of faith. The Meditationes was reassuringly entitled The Meditations of René Descartes on First Philosophy, in Which the Existence of God and the Immortality of the Soul Are Demonstrated; and the book was dedicated to “the very sage and illustrious dean of the Sacred Faculty of Theology of Paris”—i.e., the Sorbonne. The dean accepted the dedication, but in 1662 the volume was placed on the Index of Prohibited Books “until it is corrected.” It began on the same brave note as the Discours: “Today … since I have procured for myself an assured leisure in a peaceful retreat, I shall at last freely and seriously address myself to the general upheaval of all my former opinions.”93 He throws them out the window and then lets them in at the door. And not only the belief in a just and omnipotent God, but also in a human will free amid universal mechanism, and a soul immortal despite its apparent dependence upon mortal flesh. Yield as we must to the logic of an unbreakable chain of cause and effect in the world of matter and body, the freedom of our wills is one of those innate ideas which are so clear and distinct, so vivid and immediate, that no one ever doubts them in practice, however much he may play with them in abstract theory.94
The idea of God, of the self, of space, time, and motion, and the axioms of mathematics—all these are innate; that is, the soul derives them not from sensation or experience but from its own essence and rationality. (Here Locke would demur and Kant would applaud.) However, these innate ideas may remain unconscious until experience startles them into conscious form. The soul, then, is not a product of experience, but its active and originative partner in the production of thought. This “rational soul”—the ability to reason—is clearly immaterial; its ideas have no length, breadth, position, weight, or any other of the qualities that belong to matter.95 “This ‘me,’ that is to say, the soul by which I am what I am, is essentially distinct from the body, and is even easier to know than the latter.”96 Therefore this immaterial mind or soul can, and surely does, survive the body.
Were these orthodox conclusions sincere, or were they protective coloration? Was Descartes so anxious to pursue his scientific studies in unpersecuted peace that he exuded metaphysics like some befuddling mist to hamper birds of prey? We cannot say. It is possible for a man to be a good scientist—at least in physics, chemistry, and astronomy, if not in biology—and at the same time accept the basic doctrines of Christianity. In one passage Descartes affirmed that reason “does not prevent us from believing matters that have been divinely revealed as being more certain than our surest knowledge.”97 His correspondence with Princess Palatine Elizabeth is eloquently pious and orthodox. Salmasius, visiting him at Leiden in 1637, described him as “a most zealous Catholic.”98
And yet the last decade of his life was dedicated to science. He turned his rooms into a laboratory and made experiments in physics and physiology. When a visitor asked to see his library Descartes pointed to a quarter of veal that he was dissecting.99 At times he spoke like Bacon of the great practical benefits that would accrue to mankind when science had made men “the masters and possessors of nature.”100 His subjective emphasis and his confidence in deduction often led him to dubious conclusions, but he worked creatively in several sciences. He insisted that science should replace the vague and qualitative abstractions of medieval physics with quantitative explanations in mathematical form. We have noted his development of analytical geometry and his adumbration of infinitesimal calculus. He solved the problems of doubling a cube and trisecting an angle. He established the use of the first letters of the alphabet to represent known, and of the last letters to represent unknown, quantities. He seems to have discovered the law of refraction independently of Snell. He studied fruitfully great forces exerted by small means, as by the pulley, the wedge, the lever, the vise, and the wheel, and he formulated laws of inertia, impact, and impetus. He may have suggested to Pascal that atmospheric pressure decreases with altitude,101 though he was mistaken in declaring that a vacuum existed nowhere except in Pascal’s head.102 He suggested that every body is surrounded by vortices of particles whirling about it in spherical layers—a conception not unlike the present theory of magnetic fields. In optics he correctly calculated the angle of refraction; he analyzed the changes to which light is subjected by the crystalline lens of the eye; he solved the problem of correcting spherical aberration in telescopes, and designed lenses with elliptical or hyperbolic curvature free from such aberration.103
He dissected and anatomically described a foetus. He dissected (he tells us) “the heads of various animals in order to ascertain in what memory, imagination, etc., consist.”104 He made experiments in reflex action, and explained the mechanism by which the eye winks at the approach of a blow.105 He developed a theory of the emotions resembling that of William James and Carl Lange: the external cause of the emotion (e.g., our sight of a dangerous animal) automatically and simultaneously generates a responsive action (flight) and the corresponding emotion (fear); the emotion is the accompaniment, not the cause, of the action. The passions are rooted in physiology and should be studied and explained as mechanical operations. They are not in themselves bad, for they are the wind in our sails; but when not moderated by reason they can enslave and ruin a personality.
The whole universe, except God and the rational soul, may be viewed as mechanical. Remembering Galileo and the Inquisition, Descartes is careful to present the idea as hypothetical: assuming that God has created matter and endowed it with motion, we can imagine the world evolving thereafter by the laws of mechanics, without interference. The natural movement of material particles, in a universe without a vacuum, would take a circular form, resulting in diverse vortices or whirlpools of motion. The sun, the planets, and the stars may have been formed by the concentration of particles at the centers of these vortices. Just as every body is surrounded by a whirl of fine atoms—which explains cohesion and attraction—so each planet is enclosed in a vortex of particles that holds its satellites in orbit. The sun is the center of a vast vortex in which the planets are swept around it in circles. It was an ingenious theory, but it fell apart when Kepler proved that the planetary orbits are elliptical.
Descartes proposed that if our knowledge were complete we should be able to reduce not only astronomy and physics and chemistry, but all the operations of life, except reason itself, to mechanical laws. Respiration, digestion, even sensation, are mechanical; see how beneficently this principle worked in Harvey’s discovery of the circulation of the blood. Descartes confidently applied the mechanical conception to all the operations of animals, for he refused to credit them with the power of reasoning. He may have felt religiously compelled to do this injustice to animals; for he had based the immortality of the soul upon the immateriality of the rational mind, and if animals too had such minds they too would be immortal—which might be an inconvenience, if not to dog lovers, at least to theologians.
But if the human body is a material machine, how can the immaterial mind act upon it, or govern it by so unmechanical a power as free will? At this point Descartes lost his confidence; he answered desperately that God arranges the interaction of body and mind in mysterious ways, beyond our finite understanding. Perhaps, he suggested, the mind acts upon the body through the pineal gland, which is appropriately situated at the middle base of the brain.
The rashest act in Descartes’ life was his request to Mersenne to send advance copies of the Meditationes to various thinkers with an invitation to submit criticisms. Gassendi, in reply, demolished Descartes’ contentions with Gallic courtesy;106 the priest was not convinced by the ontological argument for the existence of God. Hobbes objected that Descartes had not proved the mind’s independence of matter and the brain. Privately (according to Aubrey) Hobbes “was wont to say that had Descartes kept himself wholly to geometry … he had been the best geometer in the world, but that his head did not lie for philosophy.”107 Huygens agreed with Hobbes, and thought that Descartes had woven a romance out of metaphysical webs.