Philosophy of the Modern Era

Descartes

René Descartes (1596—1650) is commonly regarded, and rightly so, as the founder of modern philosophy. He is the first philosopher of significant talent whose ideas were deeply influenced by the new physics and astronomy. While it is true that his theories retain much from scholasticism, he does not adhere to the foundations laid by his predecessors but instead seeks to construct a coherent philosophical system anew. Such an endeavor had not been attempted since Aristotle and signifies a revival of faith in human capability arising from the progress of science. His works exude a freshness that had not been found among any notable philosopher after Plato. All medieval philosophers were teachers imbued with a professional sense of superiority characteristic of their vocation. Descartes writes not as a teacher but as a researcher and scholar, eager to share what he has discovered. His style, light and unpedantic, appeals more to the educated individuals of the world than to students, and it is a remarkably superior style. It is a great fortune for modern philosophy that its progenitor possessed such exceptional literary talent. His followers, both on the continent and in England, maintained the non-professional character of his philosophy up until Kant, and some of them also preserved certain stylistic merits of his writing.

Descartes's father was a member of the parliament council of Brittany and owned a small estate. Upon inheriting his father's estate, Descartes sold the land and deposited the money in a bank, earning an income of six or seven thousand francs a year. From 1604 to 1612, he was educated at the Jesuit college of La Flèche, which, it seems, provided him with a more solid grounding in contemporary mathematics than he might have received at most universities of that time. In 1612, he moved to Paris, but growing weary of social life, he settled into seclusion in the suburb of Saint-Germain, where he focused on geometry. However, his friends found him there, so to ensure his solitude, he enlisted in the Dutch army (1617). Since peace temporarily prevailed in the Netherlands, he was able to devote nearly two years to contemplation. Yet, the onset of the Thirty Years' War prompted him to join the Bavarian army (1619). There, in Bavaria, during the winter of 1619/20, he experienced what he describes in Discourse on the Method. As the weather was cold, he climbed into a stove one morning and remained there the entire day, contemplating; by his own account, his philosophy was half-finished when he emerged, though this should not be taken too literally. Socrates typically pondered all day in the snow, but Descartes's mind only functioned well when he was warm.

In 1621, he left the army and, after visiting Italy, settled again in Paris in 1625. Yet again, friends visited him, often at times when he was still asleep (for he rarely rose before noon), so in 1628, he joined the army besieging La Rochelle, a Huguenot stronghold. When this event concluded, he decided to settle in the Netherlands, likely to avoid the risk of persecution. He was a timid man, a devout Catholic, but he shared the heretical views of Galileo. Some believed he had heard of Galileo's first (secret) condemnation in 1616. This may indeed have been the case, as he chose not to publish his major work, Treatise on Light, on which he was working. The reason was that it contained two heretical doctrines: the rotation of the Earth and the infinity of the universe. (This book was never fully published; fragments of it appeared posthumously.)

He lived in the Netherlands for twenty years (1629—1649), with the exception of a few brief business trips to France and one to England. The importance of the Netherlands in the seventeenth century—being the only country where freedom of thought prevailed—cannot be overstated. Hobbes was forced to print his books there; Locke found refuge during the five most difficult years of reaction in England prior to 1688; Bailly (an associate of the Dictionary) considered it essential to live there; and Spinoza would hardly have been allowed to produce his work in any other country.

I mentioned that Descartes was a timid man, but it may be more accurate to say that he wished to be left alone for quiet work on his pursuits. He always flattered ecclesiastical figures, especially the Jesuits, not only while he was under their influence but also after his emigration to the Netherlands. His psychology is unclear, but I tend to believe he was a sincere Catholic who sought to persuade the Church, as much in its own interests as in his, to be less hostile to modern science than it had been in the case of Galileo. Some people think his faith was merely a matter of politics; while this view is quite plausible, I do not consider it the most likely.

Even in the Netherlands, he faced annoying attacks, not only from the Roman Church but also from Protestant fanatics. It was said that his views led to atheism, and he would have been persecuted had it not been for the intervention of the French ambassador and the Prince of Orange. This outcry against him ended unsuccessfully; another, less significant, protest was made a few years later by the administration of Leiden University, which prohibited any mention of him, favorable or unfavorable. But again, the Prince of Orange intervened, advising the university not to act foolishly. This illustrates how Protestant countries benefited from the subordination of the Church to the state and from the relative weakness of non-international churches.

Unfortunately, through Chanut, the French ambassador in Stockholm, Descartes entered into correspondence with Queen Christina of Sweden, a passionate and learned woman who believed that, as a queen, she had the right to take up the great man's time. He sent her a treatise on love, a subject he had until then rather neglected. He also sent her a work on the passions of the soul, which he had originally composed for Princess Elizabeth, the daughter of the Elector Palatine. These manuscripts prompted her to invite him to her court; ultimately, he agreed, and she sent a warship for him (September 1649). It then became clear that she wanted him to give her daily lessons but could find no free time for this other than at five in the morning. This early rising, unusual for him, in the cold Scandinavian winter was far from pleasant for a man of his comforts. Moreover, Chanut fell dangerously ill, and Descartes tended to him. The ambassador recovered, but Descartes fell ill and died in February 1650.

Descartes was never married but had an illegitimate daughter who died at the age of five; he regarded this as the greatest sorrow of his life. Descartes was always well-dressed and carried a sword. He was not industrious, working only a few hours a day and reading little. When he left for the Netherlands, he took with him only a few books, among them the Bible and the works of Thomas Aquinas. His writings appear to have been composed with considerable effort over short periods, though perhaps he pretended to work less than he actually did in order to present himself as an amateur aristocrat; otherwise, his successes would hardly have been possible.

Descartes was a philosopher, mathematician, and scientist. In philosophy and mathematics, he created works of immense significance; in the natural sciences, while his contributions are honorable, they are not as remarkable as those of some of his contemporaries.

His monumental contribution to geometry was the creation of analytical geometry, albeit not in a fully developed form. He employed an analytical method predicated on the assumption that a problem is solved, and then the consequences flowing from that assumption are examined; he applied algebra to geometry. In both cases, he had predecessors, and concerning the former, there were even predecessors among the ancients. What was original to him was the use of coordinates, that is, the determination of a point's position in a plane by its distance from two fixed lines. He himself did not fully unveil the power of this method, but he did enough to facilitate further progress. This was by no means his only contribution to mathematics, but it was the most important.

The book in which he expounds most of his scientific theories is titled Principles of Philosophy; it was published in 1644. He also has other significant works: Philosophical Essays (1637), which pertain to optics as well as to geometry; one of his books is called On the Formation of the Fetus. He welcomed Harvey's discovery of circulation and always hoped (though vainly) to make some significant contribution to medicine. He viewed human and animal bodies as machines; he regarded animals as automata, entirely subject to the laws of physics and devoid of sensation or consciousness. Humans, on the other hand, differ from animals: they possess a soul, which resides in the pineal gland. There, the soul interacts with the "vital spirits," and through this interaction, the connection between soul and body is realized. The total amount of motion in the universe is constant, and thus the soul cannot influence it, but it can change the direction of the motion of the vital spirits, and hence indirectly that of other parts of the body.

This segment of Descartes' theory was ultimately renounced by his followers—first by his Dutch disciple, Geylincks, and later by Malebranche and Spinoza. Physicists uncovered the law of conservation of momentum, which posits that the total quantity of motion in the world remains constant in any given direction. This demonstrated the impossibility of the kind of interaction between mind and matter that Descartes envisioned. Accepting, as was commonly held in the Cartesian school, that every physical action constituted an influence, they concluded that the laws of dynamics were sufficient to determine the motion of matter, thereby leaving no room for any influence of the mind. This raised a conundrum: my hand moves when I will it to move, yet my will is a mental phenomenon while the movement of my hand is a physical one. Why, then, does my body behave as though it is controlled by my mind, if mind and matter cannot interact? Geylincks provided an answer to this, known as the "theory of two clocks." Suppose you have two clocks that are synchronized: whenever the first indicates the hour, the second chimes so that, if you see one clock and hear the other, you might think the first has caused the second to chime. The relationship between mind and body operates similarly. Each soul is divinely appointed to act in synchrony with the body, so that in the case of my volition, pure physical laws compel my hand to move, even though my will does not actually exert any influence over my body.

Of course, this theory was not without its difficulties. First, it was rather peculiar; second, since physical events were firmly governed by the laws of nature, mental phenomena occurring parallel to them should also be equally determined. If the theory was correct, there must have been something akin to a possible "dictionary," in which each mental phenomenon would correspond to its respective brain event. An ideal calculator could compute brain events according to the laws of dynamics and, with the help of this "dictionary," derive the accompanying mental phenomena. Even without the "dictionary," the calculator could deduce any words and actions, as they are entirely physical movements. This perspective would be difficult to reconcile with Christian ethics and the notion of punishment for sins.

However, these implications did not become apparent immediately. The emerging theory had two virtues. The first was that it rendered the soul, in some sense, entirely independent of the body, as the soul was never under the body's influence. The second was that it allowed for the recognition of a fundamental principle: "One substance cannot influence another." For there existed two substances—mind and matter—and they were so distinct that interaction between them seemed incomprehensible. Geylincks' theory explained the appearance of interaction while simultaneously denying its reality.

In mechanics, Descartes accepted the first law of motion, which states that a body, left to itself, will move in a straight line at a constant speed. However, according to Descartes, there is no such thing as action at a distance, a notion that would later be asserted in Newton's theory of gravity. There is also no such thing as a vacuum, no atoms, yet every interaction retains a character of influence. If we knew enough, we would have the capacity to reduce chemistry and biology to mechanics; the process of the seed developing into an animal or plant is purely mechanical. There is no need for Aristotle's three souls; there exists only one—the rational soul—and that only in humans.

With sufficient caution to avoid ecclesiastical censorship, Descartes developed a cosmogony reminiscent of certain pre-Platonic philosophies. "We know," he said, "that the world, as stated in the Book of Genesis, was created, but it is interesting to consider how it might have come into being naturally." He elaborated a theory of vortex formation: around the sun, there exists a vast vortex in space filled with matter, which draws in the planets along with it. The theory is clever, yet it fails to explain why the planets move in elliptical rather than circular orbits. It became widely accepted in France, where it was gradually supplanted by Newton's theory. Cotes, the publisher of the first English edition of Newton's "Principia," eloquently argued that the vortex theory leads to atheism, while Newton's theory requires God to set the planets in motion away from the sun. On this basis, he concluded that Newton's theory should be preferred.

I now turn to the two most significant works from the standpoint of pure philosophy by Descartes: "Discourse on the Method" (1637) and "Meditations on First Philosophy" (1642). For the most part, they coincide, and there is no need to consider them separately.

These works commence with Descartes' exposition of the method known as "Cartesian doubt." To establish a firm foundation for his philosophy, he resolves to doubt everything that he can possibly doubt. As he anticipates, this process may take some time; in the meantime, he decides to regulate his conduct according to ordinary, commonly accepted rules. This keeps his mind free from the potential consequences of his doubts concerning practice.

He begins with skepticism about the senses. "Can I doubt," he asks, "that I am sitting here by the fireplace in my robe?" Yes, for sometimes I have dreamed that I was here, while in reality, I lay completely naked in bed (pajamas and nightgowns were not yet in vogue). Moreover, there are instances of hallucinations among the insane, so it is possible that I might be in a similar state.

Yet dreams, like painters, provide us with copies of real things, at least regarding their elements. (You may dream of a winged horse, but only because you have previously seen horses and wings.) Hence, the corporeal nature of things in general, including aspects such as extension, magnitude, and quantity, is less easily doubted than the belief in individual things. Arithmetic and geometry, which have no connection to individual things, are therefore more certain than physics and astronomy; they are even truer regarding the dream objects that do not differ from real things in terms of quantity and extension. However, even concerning arithmetic and geometry, doubts are possible. It could be that God compels me to err whenever I attempt to count the sides of a square or add 2 to 3. It might be unjust, even in imagination, to ascribe such a lack of goodness to God, but perhaps there exists a malignant demon, as treacherous and deceitful as he is powerful, who employs all his cunning to mislead me. If such a demon existed, then perhaps all the things I see are merely illusions that he lays as traps for my credulity.

Yet there remains something in which I cannot doubt: no demon, however cunning, could deceive me if I did not exist. I may not have a body; it could be an illusion. But the matter is different with thought. "While I am willing to think that all is false, it is necessary that I, who thinks this, am something; noticing that the truth of my thought implies my existence, I concluded that this axiom, ’I think, therefore I am,’ is so solid and so certain that the most whimsical assumptions of skeptics cannot undermine it. I have reasoned that I may safely accept it as the first principle sought by me in philosophy."

This excerpt encapsulates the essence of Descartes' theory of knowledge and contains what is most significant in his philosophy. Most philosophers after Descartes placed great emphasis on the theory of knowledge, and in doing so, they owe a considerable debt to him. "I think, therefore I am" renders consciousness more certain than matter, and my mind (for me) more trustworthy than the minds of others. Thus, in any philosophy that begins with Descartes, there exists a tendency towards subjectivism and towards considering matter as the only entity that can be known, if indeed anything can be known by deducing from what is known about the mind. These two tendencies manifest in both continental idealism and British empiricism; however, in the former, they are proclaimed with solemnity, while in the latter, they are acknowledged with regret. Just recently, an attempt was made to escape this subjectivism through a philosophy known as "instrumentalism," but I shall not discuss that here. With this exception, modern philosophy has broadly embraced the formulations of its problems as articulated by Descartes, while not accepting his solutions.

The reader may recall that St. Augustine proposed an argument strikingly similar to Descartes' principle, cogito ergo sum. However, he did not assign it due significance, and the problem he sought to resolve based on this principle occupied only a small portion of his reflections. Therefore, one must acknowledge Descartes' originality, albeit it lies less in the discovery of arguments than in the understanding of their importance.

After Descartes laid a solid foundation, he set about reconstructing the entire edifice of knowledge. The existence of the self was proven through the assertion that I think. Therefore, I exist when I think, and only then. If I were to cease thinking, there would be no proof of my existence. I am a thinking thing; a substance whose entire nature or essence consists solely in thought and which, to exist, requires neither space nor any material thing. Hence, the soul is entirely distinct from the body and more easily known than the body; it would be all that it is even if the body did not exist at all.

Next, Descartes asks himself: why is the principle "cogito, ergo sum" so evident? He concludes that this is only because it is clear and distinct. Thus, he adopts the general rule that all things we perceive very clearly and distinctly are true. However, he admits that it can sometimes be challenging to discern which things are perceived distinctly.

Descartes uses the term "thinking" in a very broad sense. A thing that thinks, he states, is one that doubts, understands, perceives, affirms, denies, wills, imagines, and feels, for feeling, as occurs in dreams, is a form of thinking. Since thought is the essence of the mind, the mind must always think, even during deep sleep.

Now, Descartes raises the question again about our knowledge of bodies. He takes a piece of wax from a honeycomb as an example. Some qualities are directly evident to the senses: wax has the taste of honey, smells of flowers, has a certain visible color, size, and shape; it is hard and cold, and it makes a sound when struck. Yet, if you place it near the fire, these qualities change, although the wax as such continues to exist; thus, what was presented to the senses was not the wax itself. The essence of wax consists of extension, flexibility, and motion, which are understood by the mind rather than the imagination. The thing that is wax, in itself, cannot be perceived sensibly, as it is equally involved in all phenomena of wax presented to various sensory organs. The perception of wax does not consist of sight, touch, or representation... but is solely the discernment of the mind. I see the wax no more than I see people in the street when I notice hats and coats. "Through the mere capacity for judgment within my spirit, I understand what I seemed to see with my eyes." Knowledge through the senses is chaotic and shared with animals; but now I remove the coverings from the wax and mentally perceive it stripped bare. That I see the wax with my sensory organs reliably speaks to my own existence, but not to the existence of the wax. The knowledge of external things must be achieved through the mind, not the senses.

This leads to a consideration of the various types of ideas. The most general errors, Descartes claims, consist in assuming that my ideas are similar to external things. (The word "idea," as Descartes commonly used it, includes sensory perceptions.) Apparently, there are three kinds of ideas: 1) innate; 2) foreign and coming from outside; 3) invented by myself. We naturally presume that the second kind of ideas is identical to external objects. We suppose this partly because nature teaches us so, and partly because such ideas come independently of our will (that is, through the senses), making it seem reasonable to assume that an external thing impresses its image upon me. But is all this sufficiently reasonable? When I speak of what "nature teaches," I merely imply that I have a certain inclination to believe this, not that I perceive it through the natural light of my mind. What is discerned through the natural light of my mind cannot be denied, but mere inclination can be directed towards falsehood. And regarding sensory ideas, which are involuntary, this is not an argument, for dreams are also involuntary, even though they do not come from outside. Therefore, the grounds for assuming that sensory ideas come from outside are not convincing.

Moreover, sometimes there are two distinct ideas of the same external object, such as the sun, as it is perceived by the senses, and the sun as believed by astronomers. Both these ideas cannot be equally representative of the sun, and reason indicates that the one derived directly from experience must be the least representative of it.

But these arguments do not refute the skeptical contentions that raise doubts about the existence of the external world. This may first be addressed by proving the existence of God.

Descartes' proofs of God's existence are not particularly original; they are primarily derived from scholastic philosophy. They are more clearly articulated by Leibniz, and I shall not consider them until we turn to him.

Once the existence of God is established, everything else may be easily inferred. Since God is good, He would not act like the deceitful demon that Descartes invented as a basis for doubt. Thus, God has given me such a strong inclination to believe in the existence of bodies that He would be deceiving me if nothing existed; therefore, bodies exist. Furthermore, He has likely given me the ability to correct my errors. I employ this ability when I operate from the principle that all that is clear and distinct is true. This allows me to know mathematics as well as physics, provided I remember that I must ascertain the truth about bodies through the mind alone, rather than through the joint use of the mind and body.

The constructive aspect of Descartes' theory of knowledge is significantly less interesting than his earlier negative component. Here, he employs all sorts of scholastic principles, such as the notion that an effect can never be more perfect than its cause, which somehow escaped initial critical scrutiny. No justifications for accepting these principles are provided, although they are certainly less self-evident than one's own existence, which is so loudly proven. Much of what is asserted in the "Meditations on First Philosophy" is contained in Plato's "Theaetetus," St. Augustine, and St. Thomas.

The method of critical doubt, although Descartes himself applied it very tentatively, holds great philosophical significance. From a logical perspective, it is clear that it could yield positive results only if his skepticism were to cease somewhere. If there is to be both logical and empirical knowledge, then there must also be two kinds of constraints: indubitable facts and indubitable principles of inference. Descartes' indubitable facts are his own thoughts, using the term "thought" in the broadest sense. His starting premise is "I think." Yet here, the term "I" is logically incorrect; he ought to have formulated his initial premise as "There are thoughts." The word "I" is convenient grammatically, but it does not describe the facts. When he further asserts, "I am a thinking thing," he is already uncritically employing the apparatus of categories inherited from scholasticism. He nowhere proves that thoughts require a thinker, nor provides grounds for believing this, other than in a grammatical sense. However, the decision to regard thoughts rather than external objects as the primary empirical certainties was of great importance and had a profound impact on all subsequent philosophy.

Descartes' philosophy is significant in two other respects. Firstly, it led to the completion or near-completion of the dualism of mind and matter, which began with Plato and developed largely for religious reasons within Christian philosophy. Aside from the curious writings on the pineal gland left by Descartes' followers, the Cartesian system depicts two parallel yet independent worlds: the world of the mind and the world of matter, each of which can be studied without regard to the other. The notion that the mind does not move the body was a new idea, explicitly stated by Gassendi and implicitly suggested by Descartes. This had the advantage of allowing the assertion that the body does not move the mind. In the "Meditations on First Philosophy," there is a substantial discussion regarding why the mind feels "sorrow" when the body experiences thirst. The proper Cartesian response was that the body and mind are akin to two clocks, with one indicating "thirst" and the other indicating "sorrow." However, from a religious perspective, this theory possessed a serious flaw, leading me to the second characteristic of Cartesianism mentioned above.

In general, the Cartesian theory regarding the material world was firmly deterministic. Living organisms, like inanimate matter, were governed by the laws of physics; there was no longer a need, as in Aristotelian philosophy, for entelechy or a soul to explain the growth of organisms and the movements of animals. However, Descartes allowed for one small exception: the human soul could, at will, change the direction of the vital spirits, even if not their quantity. Yet this contradicted the very essence of the system and conflicted with the laws of mechanics; thus, it was abandoned. Consequently, all movements of matter were determined by physical laws, and by virtue of parallelism, mental phenomena must also be equally deterministic. Thus, Cartesian thinkers faced difficulties concerning free will. For those who paid more attention to Descartes' science than his theory of knowledge, it was not difficult to extend his theory that animals are automatons; why not assert the same about humans and simplify the system, making it consistently materialistic? This step was indeed taken in the eighteenth century.

Descartes faced an irreconcilable dualism between what he derived from the science of his time and the scholasticism he studied at La Flèche. This led him into contradictions, yet it also led him to articulate more fruitful ideas than any logically consistent philosopher. The inconsistency of his views may have made him merely the founder of a new scholasticism, whereas the contradictions in his views rendered him the source of two important yet divergent schools of philosophy.