Descartes (Cartesius), René

DESCARTES (Cartesius), RENÉ. - Philosopher and scientist, b. at La Haye, in Touraine, on 31 March 1596, d. at Stockholm on 11 Feb. 1650. He completed his studies (1604-12) at the renowned college of La Flèche, run by the Jesuits, and there received a thorough literary and scientific education: even when his thought carried him in another direction, he always retained gratitude toward his first instructors and educators. His intellect, superior to the common, revealed itself at once; great was his eagerness for knowledge. Having taken his degree in law at the University of Poitiers, after some travels he entered, in 1618, as a gentleman volunteer into the Dutch army of Prince Maurice of Orange first, and then into the army of Duke Maximilian of Bavaria. Around this time his vocation to the speculative sciences, especially to physico-mathematics and geometry, was determined. At the beginning of the winter of 1619 he was at Neuburg, a Bavarian city on the Danube, to spend there those months of military service: here he had long leisure, as he relates, to « converse with his thoughts ». And here he had the first idea of a general method for the acquisition of knowledge, which he afterward elaborated and set forth later. It seems that the idea flashed upon him in a dream on 10 Nov., which he interpreted as a heavenly sign of a task to which he was called, wherefore, in thanksgiving, he made a vow to go on pilgrimage to the Holy House of Loreto: perhaps he fulfilled this vow some years later, when he came to Italy, going as far as Rome (1623-25). On his return, he is often found in Paris, where, probably, he strengthened his friendship with Fr. Marin Mersenne, of the Minims, who had also come out of the college of La Flèche, and who was also much engaged in the scientific movement, and, at the same time, a zealous defender of the religious faith against the atheists and the « libertines » of the rationalistic current, which was already spreading in this century. Mersenne would afterward be D.'s most assiduous correspondent, and often the intermediary of his relations with the learned men, physicists, mathematicians, philosophers and theologians of the time. In 1628 D. met with Card. de Bérulle, founder of the Oratory, to whom, it seems, he set forth the program of work that he intended to carry out, receiving from him encouragement and almost the confirmation of the idea of a mission entrusted to him by God. He already felt himself mature for the undertaking, wherefore, in order to withdraw from distractions and dedicate himself entirely to it, he decided to establish his residence in Holland, a country then peaceful, in which he could live « as solitary and tranquil as in the most remote deserts ».

To 1628-29 there very probably goes back the composition of his Regulae ad directionem ingenii, which he then left unfinished (they were published posthumously only in 1701): here his new method was already set forth at length, which, taking its inspiration from the process of construction of the new experimental science, represented at that time by Galileo, emphasized its epistemological aspect, with a predominance, however, of the purely mathematical part. Here too is already the reform of geometry and of the algebra then in use, the one, according to him, too enslaved to figure, and the other hampered by complicated signs and too intent on practical results (the introduction of the signs is due to him simpler signs a, b, c for known quantities, x, y for unknown ones, and the use of exponents to represent powers). But the idea that dominates all the others is that of a mathesis universalis, a pure science of relations and proportions, a kind of "pure mathematics," which was to become, as it were, "the science of all sciences." To this period belong two other writings, which he reworked and published later: a sketch of his new metaphysics, and a treatise on physics (Traité du monde). The failure to publish this second work at that time was justified by him on the ground that, while he was about to finish it, news reached him of the condemnation of Galileo for the Copernican doctrine, which he too accepted.

But by now the name of D. and the fame of his innovative genius 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 questions, and therefore placed it at the head of the volume, before three essays on physics and mathematics (at that time "natural philosophy" also included these subjects): La dioptrique, Les météores, La géométrie. When it appeared, this second part was the most read and discussed, and only later, when D.'s philosophical thought came to be considered independently of his scientific thought, did people begin to publish the Discours without the essays that followed it. It had, in fact, a very personal, autobiographical tone, and presented itself (being written in the vernacular, that is, in French) as a discourse addressed to a much wider public than that of the learned and professional philosophers: a kind of philosophy of "common sense," which anyone outside scholastic jargon could understand. It suffices to recall part 4, in which the famous principle of the Cogito, ergo sum is set forth, that is, the principle of the certainty and the primary existence (in comparison with the existence of the external world) of the very one who, by thinking, makes existence a problem for himself, and is therefore conscious of himself (self-consciousness). This principle is followed by the other, that of the existence of God, for which D. proposes a new demonstration, in his view irrefutable and more certain than mathematical demonstrations themselves, because it does not start from the world (as was customary in scholastic philosophy), but from the I, that is, from the very existence of the being conscious of himself, who perceives his own limits, his own imperfections, and therefore necessarily postulates, in the very act of recognizing those limits and those imperfections, an infinite and perfect Being, from whom he derives.

This was followed by the Meditationes de prima philosophia (Paris 1641; the French version, revised by D., appeared in 1647; placed on the Index, decr. 10 Oct. 1663, 22 May 1720). Before publication he circulated the text of this writing among certain philosophers and theologians, through Mersenne, so that they might raise objections to it, to which he would then reply. The text indeed appeared accompanied by these Objections and Replies. Most of them are directed at those points in which the break with traditional scholastic philosophy was evident. But even philosophers already outside this tradition, such as Hobbes and Gassendi, offered lively opposition. A. Arnauld, who already felt the fascination of this new philosophy, from that time pointed out one of its most obscure and difficult points: the doctrine of the union of soul and body in man, which for D. was a relation of two wholly heterogeneous substances, the one conscious of itself (thinking), the other devoid of all consciousness and entirely material (endowed, in the end, with the sole attribute of extension, to which D. reduced the essence of all matter). This dualism of thinking substance and extended substance had, to be sure, the advantage of purifying the concept of the spirituality of the soul from every corporeal, material image (and thus of better ensuring its immortality), but, on the other hand, it also made the real union of those two substances in the concrete unity that is the human person more obscure and arduous to explain. This is, in fact, the weakest point of Cartesian philosophy, which, on the one hand, seemed to raise the proper nature of the human soul almost to the angelic, and, on the other, lowered animal nature to mere automatism: for, according to D., the animal too is like a machine constructed by nature, explicable by the sole elements of matter and motion, even if infinitely more subtle and complicated than the mechanisms that man too can construct. As the best justification that D. could give of his dualism, one should recall Les passions de l'âme (Paris 1649; placed on the Index, donec corrigatur, decr. 20 Nov. 1663), in which he showed that he could equally well explain, by his bodily automatism (which did not undermine, but rather, in his view, made more evident the freedom of the spirit), the moral life of man.

As regards the religious aspect, it may be said that Catholic theologians, though generally divided and often uncertain in their appraisal of this new philosophy, respected the undoubtedly orthodox intentions of the author, who always openly professed his Catholicism, although he was careful not to enter into disputes concerning dogmas (only once did he attempt to explain transubstantiation in the Eucharist by his principles). Moreover, this philosophy took up again that theme of interiority which had been proper to St. Augustine, and reconstructed on this theme the ontological argument proper to St. Anselm. That it departed from scholastic philosophy, especially from that of St. Thomas, did not seem sufficient reason to condemn it, if, in the end, it reached the same result in questions concerning reason no less than faith. Not so thought, however, certain Protestant theologians of Holland, among them Gisbert Voëtius, rector of the University of Utrecht, who accused D. of atheism, had his doctrines condemned by the academic senate, and even obtained a decree from the city authorities, according to which D. was to be expelled and his writings publicly burned. But the Prince of Orange and the ambassador of France protected the philosopher, and the sentence did not take place. Meanwhile he was well aware that he could not win over the Catholic milieu unless he convinced it of the superiority of his philosophy over scholastic philosophy (to which, moreover, he remained bound far more than he supposed). At first, therefore, he thought of writing a work in which, to that end, his doctrines would be compared with the traditional ones; then he changed his mind and decided to set out his doctrine again in a more systematic form and, as far as possible, closer to that in use in the schools, with the secret hope that his treatment might find a place there. Thus the Principia philosophiae (Amsterdam 1644) came forth, in 4 books, translated into French by the abbé Picot in 1647, of which the first is devoted exclusively to philosophical principles, and the other three comprise the fundamental sum of Cartesian physics.

Meanwhile, the Protestant theologians of Holland did not leave him in peace, and he then decided to accept the invitation that Queen Christina of Sweden extended to him to come to her court in Stockholm. But he could not endure the harshness of that climate and, having fallen ill with pneumonia, he ended his life serenely, in a Christian manner.

Cartesian philosophy powerfully stimulated the speculative vein of the great metaphysicians who came shortly afterward — Spinoza, Malebranche, Leibniz — while it was not without influence on his contemporaries and adversaries Hobbes and Gassendi, already mentioned, and on Locke. But since the habit has become established of regarding the doctrine of those first thinkers almost as an inevitable logical development of Descartes', it is appropriate to define more precisely the problem peculiar to Descartes in his works, which is different from the one his aforementioned successors set themselves.

Descartes is, first of all, a scientist, a physicist-mathematician, who nevertheless made of science, and properly of mathematical physics, a problem that is also philosophical, inasmuch as he asked what were, and ought to be, its metaphysical presuppositions (in this also lies the difference between him and Galileo, besides the other, already mentioned, of mentality — the one predominantly mathematical, the other more that of an experimental physicist). It is probable that those presuppositions flashed upon Descartes' mind as early as 1628-29 with sufficient clarity, but the exposition of them was, in reality, formulated in three successive stages: in the Regulae, in the Discours, 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 2). Here, instead, the rules are 21, and there would have been even more had Descartes continued along this path. But this does not matter: for the essential is already in the first part of the work (up to rule 12). What matters more is that here the foundation is deepened in a direction far more critically logico-gnoseological. First of all, in fact, the superiority of the pure intellect over the faculties of sense, imagination and memory is asserted, and their relations are studied, whereby the latter can harm the pure intellect but can also be of help to it: everything lies in the clarity and distinctness of ideas, which is obtained precisely by purifying them from the influence of corporeal, external things, to which such faculties are subject. Ideas are the immediate object of the intellect, called intuition when their relation is grasped immediately, deduction when it is grasped through a series of relations that connect, in the end, one idea to another remote one. Hence the necessity of memory, and the advice to repeat the chain of the process until, by abolishing in a certain way the dependence on memory, the deduction unfolds, so to speak, within the intuitive act itself. This is the new intuitive logic that Descartes wishes to substitute for the conceptual, syllogistic logic of Scholasticism. But what is the origin and foundation of these ideas? Here Descartes sets out his doctrine, which no longer appears in later works, of simple natures, that is, of the fundamental constitutive ideas for the knowledge of things. But it remains implied, it seems, that it is then left to the scientist's ingenuity to establish case by case which ideas are to be determined as fundamental with respect to others, and in their mutual relation, given that this logic is meant to be above all, not simply an art of reasoning, but an ars inveniendi. The same confidence, then widespread, that it was a question of method, of substituting a new "organon" (Bacon) for the one of Aristotelian origin, that is, a set of rules and precepts more closely adhering to the procedures of the new experimental science, is in Descartes balanced by the conviction, explicitly declared, that more than rules and precepts what counts is constant exercise in scientific inquiry, and moreover "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, with judgments on the various kinds of culture, with reflections on the 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 was not evident, that is, so clear and distinct to the understanding as to exclude all doubt; reduction of problems to their simple constitutive elements; gradual synthesis toward more complex knowledge; enumeration and final review. While awaiting the ability to reduce even morality to philosophically grounded principles, and since life permits no delay, Descartes gives in part 3 a so-called "provisional" morality, consisting of a few maxims: to conform to the ideas and customs of social life, always preserving one's own freedom of judgment; to be constant and resolute in action; to master one's desires and seek happiness within oneself; to devote oneself to a profession useful to oneself and to others. Part 4 is central, and will provide the fundamental theme of the Meditationes. In it he proposes the famous "methodical doubt," from which there finally emerges the irrefutable evidence and certainty of the cogito against all skepticism. Hence the reduction of the soul to pure self-consciousness. There follow the proofs of the existence of God: a) from the idea of perfection, which cannot derive to us except 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 the Good: but what sense would "truth" and "good" have if God did not exist?

Subsequently, Descartes was reproached by many for incurring, in this demonstration of the existence of God, a "vicious circle," and even today it is widely discussed: it seems, in fact, that he grounds his demonstration, according to his methodological principle, on the clarity and distinctness of ideas, while he then avails himself of the existence of God, posited as a guarantee of the truth of our thought, to secure the truth of that principle. Descartes defended himself, even then, against this accusation, but poorly: he did not come to see clearly that here there is what Rosmini later called a "solid circle," and that, moreover, if the criterion of clarity and distinctness could have its validity in the logico-gnoseological field, here, for the existence of God, there was a deeper reason, according to his own doctrine, in the exigency, to which his cogito points, of a value that transcends that of merely human thought. Part 5 first sets out the architectural lines of his cosmology, then dwells longer on the exposition of the movement of the heart, taken as an illustrative example of his universal mechanistic conception. Here Descartes discusses the theory of the circulation of the blood, then recently discovered by Harvey, and proposes a different explanation, not a happy one, but more in conformity with his "automatism." In part 6, emphasis is given to the also practical, utilitarian aspect of science, and to the necessity of experience and collaboration for scientific progress.

A varied, panoramic work, this Discourse, enlivened and sustained by the attraction of an elegant and easy style, of a fine, open and shrewd intelligence, which became the model of the French spirit. The Meditations, on the other hand, 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 are pervaded throughout by an inner dramatic impulse, by a sense of problematicity (as it is said today). Hence the peculiar fascination of this work, brief in itself, in its text, but which then developed at length in the added discussion of the Objections and Replies, which is a more technical part, but no less instructive and attractive for the scholar, because in it the difficulties of the exposition are revealed. The first two meditations rework, in extent and depth, the grounds of the initial doubt, carried to the point of paradox, where dream is no longer distinguished from waking, and it may even be admitted that an evil genius distorts for us, in our intelligence, the reality of every thing; and they further clarify the meaning of the cogito posited as the principle of the new philosophy. D., first, in the title of the Meditations had announced that in them the existence of God and "the immortality of the soul" were demonstrated. Then he realized that a true and proper demonstration of the latter could not be given by philosophy alone, and therefore restricted his thesis, with the title, to the "real distinction of the soul from the body in man." Hence here he insists on this distinction, from which it must follow that the soul is not subject, in itself, to perishing as the body is. The III meditation deals with the existence of God. Here the celebrated distinction of ideas is given: innate (which we find again 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 any doubt: whence else could it ever 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 mark imprinted on our soul of its divine origin.

But here a possible objection arises: are we not subject to error even in the reasonings that seem to us most well founded? and can it not therefore happen that, even while seeing clearly and distinctly that this idea of God implies his existence, we deceive ourselves? The problem is discussed in the IV meditation, where the other, equally celebrated, Cartesian theory is set out: that error depends not on the intellect but on the will, which, insofar as it is free, has an extension superior to that of the intellect alone, and can therefore induce us to give judgments even when we do not conceive clearly and distinctly. In the V meditation he passes to the problem of the external world, clarifying first of all what the proper essence of material things is (extension); but from this the occasion is taken for a further proof of the existence of God, inasmuch as, while for all other things the essence does not imply existence, only in God is it found that essence and existence coincide (a resumption of the ontological argument). In the VI meditation, finally, the question of the existence (not simply of the essence) of the external world is discussed. Not that D. wishes, or has ever really wished, to doubt this existence: it is given immediately in sensation; but, since for D. sensations are obscure and confused cognitions, which acquire the value of knowledge only when their content is elaborated, distinguished and clarified by the intellect, so now he asks how we can "know" that existence, and what value, what meaning it has for us. Let it not be forgotten that the essence of things has been clarified above as purely mathematical, so that here "things" become that complex of sensations which were later called "subjective," that is, not corresponding to the reality of the object scientifically considered. For D. these sensations have a practical, utilitarian, biological character: nature gives us the inclination to hold them real in order to warn us of the usefulness or harm that can derive to us from things. In conclusion, these Meditations present a first attempt, for the modern age, at a spiritualism critically, philosophically grounded, although this attempt takes place on the basis of the problem of science and of knowledge, and appears, therefore, one-sided, without an adequate development of that principle of interiority which we feel in St. Augustine so full of moral and religious life. In this respect one cannot but acknowledge as just the accusation, leveled at this philosophy, of having powerfully contributed, even against its intentions, to the spread of rationalism.

The Principia philosophica were, then and for a long time, regarded as the most mature expression of Cartesian thought, and even today this is the most widespread judgment, especially among those who see in Spinoza its continuation and logical conclusion. But the deviation from the original spirit of the Meditationes appears even merely from the prominence that the concept of substance has here, in Book I, and the univocity in which, as regards it, body is placed together with soul. This parity invites of itself to overcome dualism in Spinozistic monism. It is a hybrid book, this Book I, composed in order to make the following books more easily accepted, which comprise the Physics, which, here, is what he cared about most.

Cartesian physics, insofar as it recognizes as valid only the two concepts of matter and motion, is characterized by the mechanistic ideal that inspires it throughout, and that would become the fundamental character of modern physics (so-called classical, now that physics seems to have taken another direction). But it must be added that this mechanism retains, in D., also a predominantly mathematical character, insofar as, moving away from Democritean atomism and inclining instead toward "corpuscularism," it posits the infinite divisibility of matter, denies the void and weight. The first law, here enunciated for the first time, is that of the so-called principle of inertia: "Every thing remains in the state in which it is, until nothing changes it." But it is well to bear in mind the Cartesian concept of motion, which is "the transport of a body, that is, of a part of matter, from the vicinity of those that touch it immediately, and that we consider to be at rest, to the vicinity of certain others." Motion and rest, therefore, are merely relative terms. The second law posits that "every body in motion tends to continue it in a straight line, which is the simplest of all," not excluding, naturally, that in concreto this too may result from an infinity of other motions, as is the case, for example, of a diagonal that results from the motions in the two directions of the 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 the mechanics of bodies, such as elasticity, mass, potential energy, etc., has best shown the abstractness of the purely geometric and kinematic Cartesian consideration, for which even force is reduced to the concept of the pressure of one surface against another. This lack of dynamic principles marked, then, its decline before the new Newtonian physics. Meanwhile, since the quantity of motion is for D. constant (since, he says, God created it as it is, and divine perfection also demands its immutability, so that for the conservation of the world His ordinary concurrence suffices), there is thus generated, in the absence of the void, a vortical motion (tourbillon), which then breaks up into different systems corresponding to those of the stars and planets. Hence, then, also his theory of the fundamental elements, of which the subtlest is that of light, which, according to D., propagates instantaneously, like motion in a stick. We shall not go further into the examination of the other doctrines. But it must be remembered that the prevalent mathematical character of this physics, while it induces it sometimes to posit hypotheses or suppositions that still smack of the apriorism of late Scholasticism (and against which experimental physics from Newton onward would direct its barbs: hypothesis non fingo), on the other hand gives this physics a more vivid sense of construction, indeed of reconstruction, as is, in effect, the work of science, which, in this respect, stands almost as an interpretation of God's original creative work.

Cartesian physiology, too, has, as was hinted in connection with animal automatism, a strictly mechanical character. Already in the Discours, in place of Harvey's principle of contractility, which to him smacked of "occult power," he substitutes "one of those fires without light" similar to that which warms hay or that which makes new wine boil. The circulation of the blood he explains thus. And the parts more fluid and rarefied by the heat in the blood, and diffused throughout the entire organism, form the animal spirits, especially in the brain, indeed in the pineal gland, and from there moving rapidly, like the particles of a flame in combustion, they move the nerves and the muscles. In the pineal gland the soul has its most proper seat.

Voltaire, disseminating in France Locke's empiricism and Newtonian physics, called Cartesian physics and metaphysics "a novel," and thus contributed to the oblivion into which it rapidly fell in the following century. Into this "novel" fell also the well-known spiritualist note, and there remained only the other aspect of Cartesianism, the rationalistic one, of which the Enlightenment of the century made use and abuse, especially against Catholic dogma.

Armando Carlini