DESCARTES (Cartesius), René. - Philosopher and scientist, b. at La Haye in Touraine on 31 March 1596, d. at Stockholm on 11 February 1650. He pursued his studies (1604–12) at the renowned Jesuit college of La Flèche, where he received a thorough literary and scientific education. Even when his thought took a different direction, he always retained gratitude toward his first instructors and educators. His superior intellect revealed itself at once; he was possessed of a great thirst for knowledge. After taking a degree in law at the University of Poitiers, and after some travels, he entered in 1618 as a volunteer gentleman the Dutch army of Prince Maurice of Orange, and later the army of Duke Maximilian of Bavaria. It was about this time that his vocation for speculative sciences, especially physical-mathematics and geometry, became determined. At the beginning of the winter of 1619 he was stationed at Neuburg, a Bavarian city on the Danube, where he spent those months of military service. Here, as he himself relates, he had ample leisure “to commune with his thoughts.” It was here that he first conceived the idea of a general method for the acquisition of knowledge, which he later developed and expounded. The idea seems to have come to him in a dream on 10 November, which he interpreted as a celestial sign of a task to which he was called; in thanksgiving, he made a vow to go on pilgrimage to the Holy House of Loreto. He may have fulfilled this vow a few years later when he came to Italy, even reaching Rome (1623–25).
On his return, he is often found in Paris, where he probably renewed his friendship with the Minim Father Marin Mersenne, also a graduate of the college of La Flèche and deeply engaged in the scientific movement, while at the same time a zealous defender of religious faith against atheists and the “libertines” of the rationalistic trend already spreading in that century. Mersenne would later become Descartes’ most assiduous correspondent and, through him, Descartes often maintained relations with the learned men, physicists, mathematicians, philosophers, and theologians of the time.
In 1628 Descartes met Cardinal de Bérulle, founder of the Oratory, to whom he seems to have outlined the program of work he intended to pursue, receiving encouragement and almost confirmation of the idea that a mission had been entrusted to him by God. He already felt himself mature for the undertaking, and so, to remove himself from distractions and dedicate himself entirely to it, he decided to settle in Holland, a then peaceful country where he could live “as solitary and tranquil as in the most remote deserts.”
The composition of his Regulae ad directionem ingenii probably dates from 1628–29, though he left it unfinished (it was published posthumously only in 1701). Here he already set forth in detail his new method, which, drawing inspiration from the process of constructing the new experimental science represented at the time by Galileo, accentuated its epistemological aspect, though with a predominance of the purely mathematical part. Here too is to be found his reform of the geometry and algebra then in use: the former, in his view, too enslaved to figures, and the latter encumbered by complicated signs and too intent on practical results (to him is due the introduction of simpler signs: a, b, c for known quantities, x, y for unknowns, and the use of exponents to represent powers). But the idea dominating all others is that of a mathesis universalis, a pure science of relations and proportions, a kind of “pure mathematics,” which was to become like “the science of all sciences.”
To this period also belong two other writings, which he reworked and published later: an outline of his new metaphysics and a treatise on physics (Traité du monde). The non-publication at that time of this second work was motivated by the fact that, just as it was about to be completed, news reached him of the condemnation of Galileo for the Copernican doctrine, which he too accepted.
By now, however, the name of Descartes and the fame of his innovative intellect had spread among the learned, so that he finally decided to publish something. This is the historical origin of the celebrated Discours de la méthode (Leiden 1637), commonly regarded as the first clear announcement or manifesto of modern philosophy. In reality, he published it simply as an introductory essay to justify his method in scientific matters, prefacing it in the volume with three essays on physics and mathematics (at that time “natural philosophy” included these subjects): La Dioptrique, Les Météores, La Géométrie. When it appeared, this last was the part most read and discussed; only later, when Descartes’ philosophical thought began to be considered independently of his scientific thought, did the Discourse begin to be published without the essays that followed II. The Discourse had, in fact, a very personal, autobiographical tone, and, being written in the vernacular, i.e., in French, it presented itself as a discourse addressed to a public much wider than that of professional scholars and philosophers: a kind of philosophy of “common sense,” which anyone outside of scholastic jargon could understand. It suffices to recall the fourth part, in which is set forth the famous principle of the Cogito, ergo sum, i.e., the principle of the certainty and primal existence (in comparison with the existence of the external world) of the very person who, in thinking, makes existence a problem and is therefore conscious of himself (self-awareness). To this principle follows another, that of the existence of God, for which Descartes proposes a new proof, which he considers irrefutable and more certain even than mathematical proofs, because it does not start from the world (as was customary in Scholastic philosophy), but from the ego, i.e., from the very existence of the being conscious of himself, who perceives his own limits and imperfections, and therefore necessarily postulates, in the very act of recognizing those limits and imperfections, an infinite and perfect Being from whom they derive.
At this point followed the *Meditationes de prima philosophia* (Paris 1641; the French version, revised by the author, appeared in 1647; placed on the Index, decrees of 10 Oct. 1663, 22 May 1720). Before publication, he circulated the text among several philosophers and theologians through Mersenne, inviting their objections, to which he would then respond. The published work indeed appeared accompanied by these Objections and Replies. Most of these objections targeted points where his philosophy clearly diverged from traditional Scholasticism. Even philosophers outside that tradition, such as Hobbes and Gassendi, vigorously opposed him.
A. Arnauld, already captivated by this new philosophy, immediately highlighted one of its most obscure and difficult points: Descartes’ doctrine of the union of soul and body in man, which for Descartes was a relationship between two entirely heterogeneous substances—one conscious of itself (thinking), the other devoid of all consciousness and entirely material (possessing only the attribute of extension, which Descartes reduced to the essence of all matter). This dualism of thinking substance and extended substance had the advantage of purifying the concept of the soul’s spirituality from any corporeal, material imagery (thus better securing its immortality), but on the other hand, it made the real union of these two substances in the concrete unity of the human person even more obscure and difficult to explain. This, in fact, is the weakest point of Cartesian philosophy, which, on the one hand, seemed to elevate human nature almost to the level of the angels, while on the other, reduced animal nature to mere automatism—for according to Descartes, animals too are like machines constructed by nature, explicable solely through matter and motion, albeit infinitely more subtle and complex than any mechanisms humans can build.
As the best justification Descartes could offer for his dualism, one should recall *Les passions de l’âme* (Paris 1649; placed on the Index, *donec corrigantur*, decree of 20 Nov. 1663), in which he demonstrated that he could equally well explain human moral life through his corporeal automatism (which, far from undermining spiritual freedom, in his view made it more evident).
Regarding the religious aspect, it can be said that Catholic theologians, though generally divided and often uncertain in their assessment of this new philosophy, respected the author’s undoubtedly orthodox intentions, as he openly professed his Catholicism, though he carefully avoided entering into disputes over dogmas (he only once attempted to explain transubstantiation in the Eucharist using his principles). Moreover, this philosophy revived the motif of interiority characteristic of St. Augustine and reconstructed on this basis the ontological argument proper to St. Anselm. That it departed from Scholastic philosophy, especially that of St. Thomas, did not seem sufficient grounds for condemnation, provided it ultimately reached the same conclusions on questions of interest to both reason and faith. Not so, however, did some Protestant theologians in Holland, including Gisbertus Voetius, rector of the University of Utrecht, who accused Descartes of atheism, secured the condemnation of his doctrines by the academic senate, and even obtained a decree from the city authorities that Descartes should be expelled and his writings publicly burned. But the Prince of Orange and the French ambassador protected the philosopher, and the sentence was never carried out.
Meanwhile, Descartes was well aware that he could not win over the Catholic milieu unless he convinced it of the superiority of his philosophy over Scholasticism (to which, moreover, he remained more indebted than he realized). At first, he therefore considered writing a work in which his doctrines would be compared with traditional ones, but later changed his mind and decided to present his own doctrine in a more systematic form, as close as possible to the Scholastic method, in the secret hope that his treatment might be incorporated into II. Thus emerged the *Principia philosophiae* (Amsterdam 1644), in four parts, translated into French by the Abbé Picot in 1647, the first part being devoted exclusively to philosophical principles, while the remaining three encompassed the fundamental sum of Cartesian physics.
Meanwhile, the Protestant theologians of Holland did not leave him in peace, and he decided to accept Queen Christina of Sweden’s invitation to her court in Stockholm. But he could not endure the harsh climate there, fell ill with pneumonia, and died serenely and Christianly.
Cartesian philosophy powerfully stimulated the speculative vein of the great metaphysicians who followed, such as Spinoza, Malebranche, and Leibniz, while it was not without influence on contemporaries and adversaries already mentioned, Hobbes and Gassendi, and on Locke. Yet since it has become customary to regard the doctrines of these successors almost as a logical, inevitable development of Descartes’, it is well to clarify the specific problem Descartes himself posed in his works, one distinct from those of his aforementioned successors.
Descartes was, first and foremost, a scientist, a physicist-mathematician, who, however, turned his science—and specifically mathematical physics—into a philosophical problem by asking what its metaphysical presuppositions were or ought to be (this is also where he differed from Galileo, aside from the other difference noted, namely, their mentalities—Descartes’ being more mathematical, Galileo’s more that of an experimental physicist). It is likely that these presuppositions had already become clear to Descartes in 1628–29, but their exposition was formulated in three successive stages: in the *Regulae*, in the *Discours*, and in the *Meditationes*.
The *Regulae ad directionem ingenii* contain, in a much fuller and more reasoned form, the guiding criteria of scientific research, which are then summarized in the four famous rules of the *Discours* (Part II). Here, however, the rules are 21, and would have been even more had Descartes continued along this path. But this is unimportant, for the essentials are already in the first part of the work (up to Rule 12). What matters most is that here the foundation is developed in a far more critically logical-epistemological direction. First, the superiority of pure intellect over the faculties of sense, imagination, and memory is posited, and their relationships are examined, showing how the latter can hinder pure intellect but also assist it—all depending on the clarity and distinctness of ideas, which is achieved precisely by purifying them from the influence of external, corporeal things to which these faculties are subject. Ideas are the immediate object of the intellect, called *intuition* when their relationship is grasped immediately, and *deduction* when it is grasped through a series of relationships that ultimately link one idea to another. Hence the necessity of memory, and the advice to repeat the chain of reasoning until, in a sense, dependence on memory is abolished and deduction unfolds, so to speak, within the intuitive act itself. This is the new intuitive logic that Descartes sought to substitute for the conceptual, syllogistic logic of Scholasticism. But what
What are the origin and foundation of these ideas? Here the D. sets forth his doctrine, which does not reappear in his later works, of simple natures, i.e., of fundamental ideas constitutive of the knowledge of things. Yet it remains implicit, it seems, that it is then left to the ingenuity of the scientist to determine in each case which ideas are to be regarded as fundamental in relation to others, and in their reciprocal relations, given that this logic aims above all, not merely to be an art of reasoning, but an ars inveniendi. The same confidence, then widespread, that the issue was one of method, of substituting a new "organon" (Bacon) for the Aristotelian one, i.e., a set of rules and precepts more suited to the procedures of the new experimental science, is in the D. balanced by the conviction, explicitly stated, that more than rules and precepts, constant practice in scientific inquiry counts, and also "perspicacity" in intuiting, and "sagacity" in deducing.
The Discours de la méthode, on the other hand, despite its title, has a different tone and content: the question of method is touched upon only in the first two parts, and mingled with autobiographical narrative, judgments on the various kinds of culture, reflections on differences of ideas and customs among individuals as among peoples, etc. The rules are reduced to the four famous ones: never to accept anything that is not evident, i.e., so clear and distinct to the mind as to exclude all doubt; to reduce problems to their simple constituent elements; to proceed by gradual synthesis toward more complex knowledge; and to make a final enumeration and review. Pending the reduction of morality to principles philosophically grounded, and since life allows no delay, the D. sets forth in the 3rd part a so-called "provisional" morality, consisting of a few maxims: to conform to the ideas and customs of social life, while always preserving one's freedom of judgment; to be constant and resolute in action; to master one's desires and seek happiness within oneself; and to devote oneself to a profession useful to oneself and others. The 4th part is central, and will provide the fundamental theme of the Meditationes. In it the famous "methodic doubt" is proposed, from which there emerges, in the end, the irrefutable evidence and certainty of the cogito against all skepticism. Hence the reduction of the soul to pure self-consciousness. This is followed by proofs of the existence of God: a) from the idea of perfection, which cannot derive from us unless from God Himself; b) from our imperfection, which presupposes a cause of our existence other than ourselves; c) from the coincidence in God of essence and existence. Finally: we seek Truth and Good: but what meaning would "truth" and "good" have if God did not exist?
Subsequently, many reproached Descartes with falling, in this demonstration of the existence of God, into a "vicious circle," and the issue is still widely debated today: it seems, indeed, that he bases his demonstration, according to his methodological principle, on the clarity and distinctness of ideas, while then making use of the existence of God, posited as a guarantee of the truth of our thought, to assure the truth of that principle. Descartes defended himself against this charge from the outset, but poorly: he never clearly saw that what is involved here is what Rosmini later called a "solid circle," and that, in the order of things, while the criterion of clarity and distinctness may have its validity in the logical-epistemological field, in the case of the existence of God there was, according to his own doctrine, a deeper reason, in the exigency, to which his cogito points, of a value transcending that of merely human thought. In the 5th part, he first sets out the architectural lines of his cosmology, then dwells at greater length on the movement of the heart, taken as an illustrative example of his universal mechanical conception. Here the D. discusses the theory of the circulation of the blood, then recently discovered by Harvey, and proposes a different, unsuccessful explanation, more in keeping with his "automatism." In the 6th part, emphasis is given to the practical, utilitarian aspect of science, and to the necessity of experience and collaboration for scientific progress.
A varied, panoramic work, this Discourse, sustained by the attraction of elegant style and glimpses of a fine, open, and keen intelligence, which became the model of the French spirit. The Meditationes, instead, while preserving the fluidity and liveliness of thought, are more concentrated, limited to the central problem of Cartesian philosophy, which is that of the cogito, and pervaded throughout by a wholly dramatic interior tension, by a sense of problematicity (as it is called today). Hence the peculiar fascination of this work, brief in itself in the text, but then extensively unfolded in the appended discussion of Objections and Replies, which is a more technical part, yet no less instructive and attractive to the scholar, because in it the difficulties of exposition are revealed. The first two meditations rework at length and in depth the reasons for the initial doubt, carried to the point of paradox, where the distinction between dream and waking is no longer made, and it may even be admitted that an evil genius distorts in our mind the reality of everything; and they further clarify the meaning of the cogito posited as the principle of the new philosophy. The D., at first, in the title of the Meditationes, had announced that in them the existence of God and "the immortality of the soul" were to be demonstrated. Then he realized that a genuine demonstration of the latter could not be given by philosophy alone, and accordingly restricts, in the title, his thesis to the "real distinction of the soul from the body in man." Hence the insistence here on this distinction, from which it must follow that the soul is not subject, in itself, to perishing like the body. The III meditation treats of the existence of God. Here the celebrated distinction of ideas is given: innate (which we find in ourselves by pure reflection on ourselves), adventitious (which come to us from external things), factitious (of which we ourselves are the authors). The idea of God is innate, without doubt: whence else could it come to us? God is the supremely perfect Being and pure spirituality. The very idea that is in our soul demonstrates His existence, and it is like a sign imprinted in our soul of His divine origin.
Here a possible objection arises: are we not also subject to error in our reasoning, even when it seems most firmly grounded? And is it not possible, then, that even when we clearly and distinctly see that the idea of God implies His existence, we may still be mistaken? The problem is discussed in the Fourth Meditation, where the other, equally celebrated Cartesian theory of error is expounded: error does not arise from the intellect but from the will, which, being free, has a scope greater than that of the intellect alone and can thus lead us to make judgments even when we do not conceive things clearly and distinctly. In the Fifth Meditation, the problem of the external world is addressed, first clarifying the proper existence of material things (extension); but from this, an opportunity arises for a further proof of God’s existence, since while for all other things existence does not imply essence, in God alone essence and existence coincide (a reprise of the ontological argument). In the Sixth Meditation, finally, the question of the existence (not merely of the existence) of the external world is discussed. Not that Descartes wished, or ever truly intended to doubt this existence: it is given immediately in sensation; but since, for Descartes, sensations are obscure and confused knowledge, which acquire the value of knowledge only when their content is elaborated, distinguished, and clarified by the intellect, he now asks how we can “know” that existence and what value or meaning it has for us. One must not forget that the essence of things has been clarified beforehand as purely mathematical, so that here “things” become that complex of sensations which were later termed “subjective,” not corresponding, that is, to the reality of the object as scientifically considered. For Descartes, these sensations have a practical, utilitarian, biological character: nature gives us the inclination to regard them as real in order to warn us of the utility or harm that things may bring us. In conclusion, these *Meditations* present, for the modern age, an initial attempt at a spiritually grounded philosophy, albeit one that is critical and philosophical, even if this attempt is based on the problem of science and knowledge and thus appears one-sided, lacking an adequate development of that principle of interiority which we find so vividly in St. Augustine, full of moral and religious life. For this reason, one cannot but acknowledge the justice of the accusation leveled against this philosophy—that it powerfully contributed, even against its own intentions, to the spread of rationalism.
The *Principles of Philosophy* were then, and for a long time, regarded as the most mature expression of Cartesian thought, and even today this remains the most widely held judgment, especially among those who see in Spinoza its logical continuation and conclusion. Yet the deviation from the original spirit of the *Meditations* is evident even from the prominence given in Book I to the concept of substance and the univocity with which body and soul are placed on the same level. This parity invites, as it were, the overcoming of dualism in Spinoza’s monism. It is a hybrid book, this first one, composed to make the following books—which include physics, his chief concern—more readily acceptable.
Cartesian physics, inasmuch as it recognizes as valid only the two concepts of matter and motion, is characterized by the mechanistic ideal that inspires it entirely and that would become the fundamental trait of modern (so-called classical) physics, now that physics seems to have taken another direction. Yet it must be added that this mechanism retains, in Descartes, a predominantly mathematical character, in that, distancing itself from Democritean atomism and inclining instead toward “corpuscularianism,” it posits the infinite divisibility of matter, denies the void, and denies gravity. The first law, enunciated here for the first time, is that of the so-called principle of inertia: “Everything remains in the state in which it is, until something changes it.” But one must keep in mind Descartes’ concept of motion, which is “the transport of a body, or of a part of matter, from the vicinity of those bodies that touch it immediately and which we consider at rest, to the vicinity of other bodies.” Motion and rest, therefore, are merely relative terms. The second law states that “every body in motion tends to continue in a straight line, which is the simplest of all,” though it does not exclude the possibility that in concrete terms this may result from an infinity of other motions, as in the case, for example, of a diagonal resulting from motions along two sides. The third concerns the change in the quantity of motion in two bodies that collide. This is the part that, neglecting concrete elements and factors of mechanics such as elasticity, mass, potential energy, etc., best reveals the abstractness of Descartes’ purely geometric and kinematic consideration, in which even force is reduced to the concept of the pressure of one surface against another. This lack of dynamic principles later marked its decline in the face of Newtonian physics. Meanwhile, since the quality of motion is, for Descartes, constant (for he says that God created it thus, and divine perfection requires its immutability, so that the ordinary concurrence of God suffices for the conservation of the world), a vortical motion (*tourbillon*) is thus generated, lacking a void, which then breaks into various systems corresponding to those of the stars and planets. From this, too, comes his theory of the fundamental elements, the subtlest of which is that of light, which, according to Descartes, propagates instantaneously, like motion in a stick. We shall not delve further into the examination of his other doctrines. But it must be recalled that the predominant mathematical character of this physics sometimes led it to posit hypotheses or suppositions that still bore the traces of the a priorism of late Scholasticism (against which Newtonian experimental physics would direct its attacks: *hypotheses non fingo*), while on the other hand it gave this physics a livelier sense of construction, indeed of reconstruction, as is in fact the work of science, which, from this perspective, is almost like an interpretation of God’s original creative work.
Cartesian physiology, as is evident in the discussion of animal automatism, also has a strictly mechanical character. Already in the *Discourse*, in place of Harvey’s principle of contractility, which seemed to him to smack of “occult power,” he substitutes “one of those fires without light,” similar to that which heats hay or causes new wine to ferment. He explains the circulation of the blood in this way. The more fluid and rarefied parts of the blood, heated and diffused throughout the organism, form the animal spirits, especially in the brain, or rather in the pineal gland, from which they move swiftly, like the particles of a flame in combustion, to activate the nerves and muscles. The soul has its proper seat in the pineal gland.
Voltaire, popularizing in France the empiricism of Locke and Newtonian physics, called Cartesian physics and metaphysics “a romance,” and thus contributed to the rapid oblivion into which they fell in the following century. In this “romance,” the spiritualistic aspect was also lost, and only the rationalistic side of Cartesianism remained, which the Enlightenment of the century made use and abuse of, especially against the Catholic dogma.