The philosopher and mathematician René Descartes was born on 31 March 1596 in La Haye (later renamed Descartes) in Touraine. He died in Stockholm on 11 February 1650. He was the son of Joachim Descartes, a counsellor at the Parliament of Bretagne, and Jeanne Brochard, who died when he was only one year old. René Descartes inherited her ‘dry cough and pale complexion’ (‘une toux sèche et une couleur pâle’), to the extent that the doctors all claimed he would die young. For this reason, after being cared for by a nurse, he received his early education from a tutor and spent his first years in the gardens near the River Creuse; this experience would later provide descriptions of his physics with country comparisons (wine left to ferment on a grater; wind passing through a hedge, etc.). It seems that he did not enter the Jesuit college in La Flèche until the spring of 1607, where he received a solid grounding in Latin classics. He stayed there until 1615 and studied philosophy for three years with Father Étienne Noël , Pascal future correspondent on the question of the void. He also received advanced training in mathematics from Father François. Upon leaving the college, Descartes studied law in Poitiers where, in November 1616, he received a bachelor’s and a master’s degree in law. However, he soon chose to become a soldier and in 1618 left for Breda in Holland, where he joined Maurice of Nassau’s troops. His encounter with Isaac Beeckman on 10 November 1618, in front of a poster displaying a mathematical problem, reawakened his love of the sciences as cultivated by those whom Beeckman, in his Journal, called the physico-mathematicians. The two friends discussed the fall of bodies and hydrostatics and, on 1 January 1619, Descartes gave Beeckman his first work, Traité de musique, which he had just written for him. In return, Beeckman gave him a register bound in parchment on which Descartes noted his thoughts, grouped under different headings: Parnassus, Experimenta, Olympica and so on. At the start of that year, 1619, he left Breda and planned to go to Germany to prove his worth, it seems, in the imminent battles. Several letters to Beeckman show that he continued with his geometry research, particularly the important letter dated 26 March in which he describes the new discoveries he had made thanks to compasses that allowed him to trace, in a single movement, curves other than circles. With this sense of generalization, which was one of the most constant features of his character, he was already planning to bring the public ‘an entirely new science, by which can generally be resolved all the questions that can be asked concerning any quantity, be it continuous or discreet’ (‘une science toute nouvelle, par laquelle peuvent être généralement résolues toutes les questions que l’on peut proposer en n’importe quel genre de quantité, tant continue que discrète’). His trip to Germany led him to Neuburg, where, with the onset of winter, he took up residence. The Olympica notes describe the famous day, 10 November 1619, when, ‘full of enthusiasm’ (‘plein d’enthousiasme’), he discovered ‘the foundations of the admirable science’ (‘les fondements de la science admirable’). That day was followed by three dreams which he transcribed in detail and which confirmed his desire to devote himself fully to his search for the truth. A Jesuit from Neuburg, Father Molitor, presented him with a copy of Pierre Charron Sagesse, whose rules on prud’homie were partly to inspire Descartes’s moral maxims.
Little is known of the years that followed: a visit to Rennes (April 1622), a trip to Italy from 1623 to May 1625, a visit to Poitou (June 1625) in order to settle some business and, in particular, a long stay in Paris (1625–8), where Descartes became friends with Mersenne , associated with Mydorge and Morin , and formed friendships with several fathers of the Oratory ( Condren and Gibieuf ). It was during a lecture by a certain Chandoux on his ‘new philosophy’ (no doubt in November 1627) that Descartes publicly announced his plans for a philosophy with more solid foundations than popular philosophy, and he received encouragement from Bérulle . Those years were marked by advances in his research into algebra, geometry and optics, and by the progress made in his thought on the unity of the sciences and the operations of the human mind; these were already extremely well explained in his Regulae ad directionem ingenii (Rules for the Direction of the Mind), which remained incomplete and unpublished during his lifetime. The unity of the sciences is related to the unity of human wisdom which, like the sunlight, is ‘one and identical to itself no matter how different the objects are to which it is applied’ (‘une et identique à ellemême aussi différents que soient les objets auxquels elle s’applique’ – Regulum 1); the first operation of the mind is intuition, ‘a conception, formed by unclouded mental attention, so easy and distinct as to leave no room for doubt in regard to the thing we are understanding’ (‘conception de l’esprit pur et attentif, si facile et distincte qu’il ne reste aucun doute sur ce dont nous avons l’intellection’ – Regulum III). Furthermore, he formulated his thoughts on a universal mathesis or general science, which ‘explains everything that it is possible to ask on order and measure’ (‘explique tout ce qu’il est possible de demander touchant l’ordre et la mesure’ – Regulum IV).
After spending the winter in the French countryside, Descartes decided to return to Holland. In October 1628, he saw Beeckman again in Dordrecht. On 26 April 1629, he enrolled at the University of Franeker under the designation philosophus gallus. The first nine months of his stay in Holland were dedicated to writing a Latin treatise on metaphysics, which he mentions in a letter to Gibieuf on 18 July 1629 and which forms part of the matrix of the Meditationes. He did not neglect his scientific research, however, and he tried to convince Ferrier , an excellent craftsman who was famous in Paris, to come and cut new optical lenses. In April and May 1630, three letters to Mersenne enabled Descartes to formulate his theory on God’s free creation of eternal truths, a critical response to the scholastics such as Suárez and Vásquez, who held that eternal truths were independent of God. He also undertook to write in French the Traité de la lumière, which he then still called his Monde, but the plan to publish the work was abandoned after he learned of Galileo’s condemnation. In a letter to Mersenne at the end of November 1633, he wrote that if the movement of the earth ‘is false, then so too are all the foundations of my physics, because it is demonstrated to be self-evident through them’ (‘est faux, tous les fondements de ma physique le sont aussi, car il se démontre par eux évidemment’). Instead of Le Monde, Descartes announced to Mersenne, in March 1636 while visiting Utrecht, that he was to publish a work whose title expresses everything that linked the Cartesian project to the humanist inspiration of the Renaissance: Le Projet d’une science universelle qui puisse élever notre nature à son plus haut degré de perfection. Plus la Dioptrique, les Météores et la Géométrie. The following year, the work was published anonymously in Leiden under the more modest title by which it is known today: Le Discours de la méthode pour bien conduire sa raison et chercher la vérité dans les sciences. The six parts of the Discours, written as a story or ‘fable’ and forming, as Guez de Balzac said, a history of his mind, demonstrate the very complete nature of Cartesian thought, since they contain the rules of his methods, a provisional moral code, the foundations of new metaphysics, an evocation of missing physics – no doubt, as he said to Mersenne, to ‘sound things out’ (‘sonder le gué’) – with an explanation of the movement of the heart and a renewed confirmation of Harvey’s theory of the circulation of the blood. The end of the fifth part is noteworthy since, in a manner that is much more synthetic, to be sure, but also more complete than in the section of Le Monde that was to be published posthumously in 1664 under the title L’Homme, Descartes describes the automaton, defines the distinction between men and animals by men’s use of words and capacity to compose signs, and defines the ‘true man’ by the union of the human body and the reasonable soul. Equally remarkable was the plan, laid out at the beginning of the sixth part, for a practical and useful philosophy that opposed the speculative philosophy taught in schools. Descartes was often accused of planning to ‘make us resemble the masters and possessors of nature’ (‘nous rendre comme maîtres et possesseurs de la nature’) without paying enough attention to the nuance of the word ‘resemble’ and without taking sufficient account of the lines that followed and clarified his project. Indeed, for him it was not so much a question of the earth’s ‘commodities’ as of ‘looking after our health’ by searching for the ‘causes’ of our illnesses and ‘all the cures with which nature provides us’ (‘tous les remèdes dont la nature nous a pourvus’). When Descartes made public his optics and geometry, he announced what would be a major concern for him from then onwards: giving man access to full knowledge and to true medicine in which physical health contributes to true wisdom.
Along with his first publications came, via Mersenne, the first discussions and controversies: with Fermat (and Roberval ) on refraction and tangents, with Morin on light and subtle matter, and a very constructive dialogue with de Beaune on geometry. Descartes did not answer the objections to the metaphysics of his Discours that came from Gibieuf, Petit , and others, but seems to have reached the conclusion that a more complete presentation was required. From February to November 1639 he wrote the treatise on metaphysics that was to appear on 28 August 1641 in Paris under the title Meditationes de prima philosophia. The criticism he received from a Jesuit, Father Bourdin , regarding his dioptrics made him fear that the entire Society would soon turn against him, and he tried hard, through the interventions of Mersenne and Gibieuf, to gain the approval of the Sorbonne theologians. Nevertheless, although his Meditations were not actually censored, he received no letter of approval, hence his delight at receiving the kindly attention of Antoine Arnauld , who had very recently obtained his doctorate in theology. Far from carrying out a dogmatic presentation of a ‘system’ (a word that he never used to define his philosophy), or adopting the scholastic method of holding a ‘dispute’, Descartes instead followed the ‘analytical path’ in his six Meditations, and ‘shows the real way by which a given truth has been methodically discovered’ (‘montre la vraie voie par laquelle une chose a été méthodiquement inventée’ – ‘Reply to the Second Objections’). In a very modern way, Cartesian analysis reveals the temporality of thought and the difficulties of the link between the mind and inner language. Thus, immediately after the affirmation ‘I am, I exist’ (‘je suis, j’existe’), the author asks, ‘how long?’ and replies ‘as long as I think’ (‘combien de temps? A savoir, autant de temps que je pense’); later on in the second Meditation regarding the transformations of a piece of wax, he finds that ‘although I consider all these things in my mind without language, words nevertheless make me falter, and I am almost deceived by the terms of common language’ (‘encore que sans parler je considère tout cela en moi-même, les paroles toutefois m’arrêtent, et je suis presque trompé par les termes du langage ordinaire’). This new presentation of primary philosophy is considerably improved compared with the fourth part of the Discours de la méthode. From this point onwards, the doubt is expressed by the double argument of a deceitful God and an evil demi-god, through which Descartes rethinks and transforms an argument taken from Francisco Suárez’s De Falsitate. Descartes researched two ideas in succession, one on the origin of ideas as situated no longer within God’s understanding (as in the medieval tradition begun by Augustine) but rather within the human mind; the other on their nature and the causality that controls their ‘objective reality’ or representative content. These questions paved the way for a modern philosophy of ideas. The second proof of God through effects enabled a deepening of what is meant, by the phrase ‘to exist by oneself positively’ (‘ce que signifie être par soi positivement’) and, in response to his main objector, Caterus, led him to formulate the thinking of God as inexhaustible power, ‘in a certain way cause of Himself’ (‘en quelque façon la cause de soi-même’). Whereas the third Meditation conceives the human mind as finite in comparison to the infinite being that I can know without claiming to understand, the fourth Meditation proposes remarkable research into the causes of our errors, related to the two human faculties that intervene in our judgement: will and understanding. Error does not arise from our faculties themselves, which can be said to be ‘perfect in their kind’ (‘parfaites en leur genre’), but rather from the use we make of them, so that the correct use of our judgement allows us to foresee error and constitutes ‘the greatest and main perfection of man’ (‘la plus grande et principale perfection de l’homme’) (AT XI-1, 49). Thus, the idea of ‘human perfection’ (‘hominis perfectio’) is established at the heart of Cartesian metaphysics. It was to be reaf-firmed in book 1, article 37 of the Principles of Philosophy, on the subject of our freedom. Finally, the sixth Meditation, by far the longest, allows us to understand the way in which the Meditations contain, as Descartes told Mersenne, all the foundations of his physics. In this work, he formulates a long argument proving the existence of bodies and in particular of ‘my’ body; he provides proof of the real distinction between the body and the soul and demonstrates the way in which ‘I am not lodged in my body like a pilot in his ship’ (‘je ne suis pas seulement logé dans mon corps comme un pilote en son navire’) but ‘constitute a whole being, so to speak, with my body’ (‘compose comme un seul tout avec lui’), in such a way that man is said to form a single unit (‘unum quid’), according to the summary of the Meditations. The analyses of man’s sensitive nature herald developments in the Passions of the Soul. These were so innovative that, in the remarkable debate composed by the Objections et réponses, which considerably enriches our knowledge of Descartes’s primary philosophy, the final pages of the Meditations almost entirely escaped the sagacity of the various objectors (with the exception of Gassendi).
Descartes had scarcely replied to the theologians (Caterus, Mersenne, Arnauld) and philosophers (Hobbes, Gassendi) who had objected to his Meditations when he was obliged to face, on the one hand, the ‘cavillations’ of Bourdin, who this time attacked his metaphysics, and, on the other hand, the attacks against Cartesian philosophy launched by the theologian Gisbert Voet, or Voetius, rector of the University of Utrecht, which were focused on the teaching of Regius, then a follower of Descartes. Descartes supported Regius and defended himself fiercely by publishing, after the Meditations had been republished in Amsterdam in 1642, a second volume which, notably, contains his ‘Réponses au P. Bourdin’ and two letters: one to Father Dinet , provincial of the Jesuits for France, and the other to Voetius himself, in which he replies to the agressive, insulting pamphlet by Martin Schook, the Admiranda methodus, which he believed to have been inspired by Voetius. In the midst of all this controversy, the Lettre à Voetius contained a remarkable statement on the use of books (fourth part), in which Descartes develops a philosophical conception of erudition in relation to the ‘culture of the mind and of morals’ (‘culture de l’esprit et des mœurs’ – AT VIII-2, 42), which owes a great deal to the spirit of the Renaissance and to Montaigne. The outcome of the conflict with Voetius was important: the overall acceptance of Cartesian philosophy in Calvinist universities in the Low Countries was at stake. In fact, although Descartes could count on enthusiastic Cartesians such as Heereboord and Heidanus, in 1647 he clashed with the theologians from Leiden who were doing their best to have him condemned as a ‘blasphemer and worse than a Pelagian’ (‘blasphémateur et plus que pélagien’ – AT V, 5).
It was outside the universities that Descartes found a very attentive and astute interlocutor in the form of Princess Elisabeth of Bohemia. Their correspondence between 1643 and 1649 enabled the philosopher to develop his moral philosophy in the form of letters and to express some of his political thinking concerning Machiavelli. It was to Princess Elisabeth that he dedicated his new long treatise, Principia philosophiae, which was published in Amsterdam in 1644. The work was written for scholastic teachers with the aim of making it acceptable to teach Cartesian philosophy in colleges at the time. Descartes followed neither the analytical path of invention nor the synthetic order to which he had bowed in the geometric presentation given as a sequel to the ‘Replies to the Second Objections’, but rather a mode of composition by articles which allowed him to adopt some of the terminology in use in scholastics (particularly on the notions of substance, attribute and mode), without, however, abandoning the core of his thinking. This time, his new physics reached the public, but with a definition of movement that meant he avoided explicitly confirming the movement of the earth. Shortly before the end of the Principles, Descartes accepted that his philosophy was incomplete because he required more knowledge, experience and time to add two more parts ‘concerning the nature of animals and plants, on the one hand, and the other concerning human nature’ (‘touchant la nature des animaux et des plantes, l’autre touchant celle de l’homme’ – pt IV, art. 188).
One should not conclude that Descartes abandoned his study of man. The last book he published, Les Passions de l’âme, not only discusses passion but also, as the title of the first part indicates, ‘all human nature’ (‘toute la nature de l’homme’). Written at the same time as he was developing his moral philosophy in his letters to Princess Elisabeth, the treatise on Passions shows that all thought is linked to a movement of the body in such a way that acquiring human wisdom requires making good use of our passions ‘all good by nature’ (‘toutes bonnes de leur nature’). In the Principles of Philosophy, Descartes states that free will constitutes man’s main perfection. In the Passions of the Soul, under the name of generosity, he shows that man’s entire value depends on good use of his freedom. And it was finally in his letters to Father Mesland that he pursued reflection on the metaphysical question of the relationship between will and the good.
Through Chanut, the French ambassador to Stockholm, Queen Christina of Sweden became interested in Descartes’s moral philosophy and invited him to meet her. Descartes left for Sweden in September 1649. He found time to compose the verses of a ballet, La Naissance de la Paix, but the rigours of winter took a toll on his health. He contracted pneumonia and died on the morning of 11 February 1650. His influence, however, continued to grow with, in particular, Clerselier posthumous publication of his letters and his treatises L’Homme and Le Monde. Descartes left, without any doubt, the most accomplished summary of modern thought, from all the sciences of the time contemplated in their unity to a philosophy of the perfection of man considered in all his dimensions.
Discours de la méthode pour bien conduire sa raison et chercher la vérité dans les sciences. Plus la Dioptrique, les Météores et la Géométrie (Paris, 1637; trans. into Latin, Amsterdam, 1644; Discours de la méthode. Texte et commentaire, by E. Gilson, Paris, 1925).
The Philosophical Writings of Descartes, vols 1 and 2, trans. J. Cottingham, R. Stoothoff and D. Murdoch; vol. 3, The Correspondence, trans. J. Cottingham, R. Stoothoff, D. Murdoch et al. (Cambridge, 1985–91).