In this blog post, we will carefully examine how the historical context of Descartes’s era and his educational experiences sparked his criticism of the humanities and Scholastic philosophy, and how his mathematical and analytical methodology emerged from that.

Descartes’ Era and Social Context

Descartes (René) was born in France in 1596 and died in Sweden in 1650. Although the natural universe was central to his philosophy, his personal life unfolded against the backdrop of the early 17th century, particularly during the Thirty Years’ War, which shook all of Europe. Thus, even though his life was not, on the surface, at the center of military or political issues, it can be seen as closely intertwined with the political and military circumstances of the era.
France, where Descartes was born, had endured a civil war between Catholics and Protestants in the late 16th century. As a result, Henry IV sought to stabilize France as a Catholic nation, and Cardinal Richelieu further consolidated that stability. However, Protestant forces had not been completely weakened.
Descartes’ father was a judge at the High Court of Brittany and came from a family of minor nobility. He was loyal to the monarchy, and it appears that Descartes, too, maintained a similar political mindset throughout his life.
Although Richelieu was the French chief minister, his actual strategy was to strengthen France’s national power by secretly supporting domestic Protestants in opposition to Catholic nations such as Germany and Spain. Because of this policy, when the Thirty Years’ War broke out, France adopted a wait-and-see attitude, hoping to capitalize on the benefits the war might bring.

Doubts About Scholarship and Early Education

Descartes lost his mother when he was just one year old, and his father had high expectations for him from a young age. Thanks to this, Descartes was able to study at the College of La Fresche and the University of Poitiers.
Although he was an outstanding student, his kinship with the headmaster granted him a degree of freedom: he was excused from attending certain lectures and, for health reasons, was allowed to sleep in a bit longer in the dormitory. It was during this time that he developed the habit of engaging in deep thought while still in bed after waking up.
He had no intention of becoming a scholar from the outset, and his father seemed to have raised him to be a practical man, likely intending for him to become a judge like himself. However, a key reason Descartes lacked passion for scholarship was his “doubt” regarding the subjects taught at school. Although his teachers told him that scholarship was useful in life, he was disappointed to find that, in reality, it was useless. He clearly states this reason in his own writings.

Criticism of the Humanities and Moral Philosophy

Regarding the humanities, Descartes first pointed out that knowing too much about the histories of ancient nations prevents one from properly judging the present state of one’s own country. While it is said that history provides lessons, his concern was that history itself selects facts and treats only certain parts as important, thus failing to present the entire situation as it truly is. He believed that acting based on such history would lead to artificial behavior that is out of step with reality.
His greatest dissatisfaction with the humanities lay in moral philosophy. Since the Middle Ages, a humanist had been defined as someone who read Greek and Latin texts and composed excellent prose in Latin; however, from the 15th and 16th centuries onward, they came to assume the role of moral teachers.
As ancient pagan moral philosophy was reexamined outside the scope of Christian moral theology, it became the duty of humanists to discuss it; however, Descartes viewed its foundations as weak.
He argued that while ancient pagan moral philosophy encourages respect for virtue, it fails to specify what that virtue actually is and, due to its weak foundation, is akin to a “house of cards.” Descartes sought a morality grounded in certain scientific knowledge, but he felt that the humanities could not provide it.

The Need for Criticism and Analysis of Scholastic Philosophy

After studying the humanities, Descartes spent three years studying Scholastic philosophy. Although he did not explicitly state that he was dissatisfied with specific aspects of Scholastic metaphysics or natural philosophy, he criticized its logic as formally deficient.
The typical mode of exposition in Scholastic philosophy followed this format: first, a proposition whose truth or falsity was in question was presented; then, an argument was offered to prove it false; next, a counterargument was presented to demonstrate its truth; and finally, by refuting the false argument, the proposition was ultimately concluded to be true. This was similar to the style of debate practiced in universities. Descartes believed that this method prioritized the motivation to defeat one’s opponent, causing one to lose sight of the goal of clarifying the truth of the matter.
There were also methodological and logical issues. He pointed out that while the method of contrasting the pros and cons to ultimately conclude in favor of the position does, to some extent, take the premises of both sides into account, the conclusion cannot be said to have been clearly proven unless those premises undergo a thorough and in-depth examination.
He believed that philosophy must arrive at clear truth, and argued that this required “analysis”—a thorough examination of premises. It was precisely this kind of thorough analysis that was lacking in Scholastic philosophy.
In fact, Descartes acknowledged that, of all the subjects he had studied at the academy, only mathematics constituted genuine knowledge with a clearly defined status. Based on mathematical certainty, he demanded that philosophy be equally clear.
Descartes’ “method” was only formalized when he generalized this analytical process to apply not only to mathematics but also to problems in natural philosophy and metaphysics, and when he considered the possibility that it could even govern ethics. Just as the “interpretation” of geometry later requires proof, analysis must be accompanied by synthesis; therefore, the method for reaching the truth was to first trace back to self-evident premises through analysis and then prove a proposition through synthesis based on those principles.
The four rules he proposed are as follows.
1) Accept only what is acknowledged to be self-evident.
2) Analyze the problem thoroughly.
3) Proceed from the simple truths reached through analysis to more complex ones in an orderly manner (synthesis).
4) Check for any omissions.

Military Service and Experiences in the Netherlands

However, it was only later that Descartes fully mastered this method. After finishing school, he went to Paris to see the world, and then headed to the Netherlands as a soldier.
He viewed travel as “surrendering oneself to all manner of chance” and regarded the various events presented by fate as opportunities to test himself. In the real world, a wrong judgment can result in immediate punishment, and there are urgent situations that differ from those encountered while studying in a library. Sometimes crises arise that allow no room for delay, and there are instances where one must make judgments based on insufficient knowledge. He felt that, ultimately, willpower was crucial for overcoming such situations.
However, even if one’s will was tempered through real-world experience, the question of intellect remained a separate matter. Descartes observed the diverse lifestyles and customs of various regions across the empire, but he stated that he did not discover any new principles to define himself from them. One of the important insights he gained through his travels was that the lives of others are, in many cases, nothing more than “habits” shaped by fortuitous circumstances.
He recognized that even “national character” was nothing more than such a habit.
He states: “If we consider what difference there would be between the same person, endowed with the same mind, who were raised from childhood among the French or Germans, and one who lived among the Chinese or even cannibals, we realize that we cannot simply label all people with entirely different ways of thinking as ‘barbaric.’” Through his travels, he realized that people with views opposite to ours are not all barbaric, crude, or base, but that they exercise reason just as much as we do—or even more so.

Descartes’ Stay in Germany and His Mathematical View of Nature

No principle of certain knowledge was found amid the diversity and individuality of the real world. Rather, for Descartes, this revealed the universality of human reason and led to the conclusion that the search for certain principles must be directed toward reason—a faculty possessed equally by both oneself and others. Thus, after spending several years studying the “book of the world” and gaining experience, he wrote that one day he resolved: “Let me study myself. Let me use all the power of my mind to choose the path I must take.” This “one day” was in November 1619, while he was staying at an inn in Germany.
Prior to this, Descartes had gone to Breda in the Netherlands as a volunteer officer to join the Protestant army; however, at that time, the Netherlands had been in a 12-year truce with Spain since 1609, so there was no fighting. During his stay in Breda, Descartes met the scholar Isaac Beeckman, who was working on a project to mathematically systematize natural philosophy. In modern terms, this was an attempt at physics research.
Beeckman held views similar to those of Galileo and Gassendi; adopting an atomic theory that posited all objects as composed of fundamental particles, he sought to establish a mechanical view of nature by mathematically investigating the laws of motion governing those particles. Descartes joined forces with Beckman, and the two conducted joint research during the last two months of 1618. Their research topics included the problem of fluid pressure and the laws of falling bodies, and Descartes provided Beckman with mathematical assistance. Beckman shared with Descartes his vision of a mathematical view of nature, which led Descartes to realize that mathematics contributes to the understanding of the entire universe, going beyond merely aiding the skills of carpenters and stonemasons.
Descartes left the Netherlands the following spring and headed for Germany, where he underwent a major intellectual transformation that fall. When war broke out in Germany around this time, he enlisted in the military; this coincided with the start of the Thirty Years’ War.
However, Descartes’ focus remained on intellectual matters rather than military action. In a letter to Beckman, he revealed that he was conceiving a new discipline capable of generally solving various problems concerning all quantities, whether continuous or discrete, and wrote that he had begun to envision a universal mathematics combining geometry and algebra. This signaled that the generalization of the analytical method was underway.
Meanwhile, Descartes’ inclination toward natural philosophy extended not only to Beckmann’s atomic theory but also to the mystical and symbolic speculations found in the works of Paracelsus and the mathematical astronomer Kepler. At that time, Germany was home to the Rosicrucians, a secret society seeking to reform the world, whose ideas were linked to Paracelsus’s speculative natural philosophy. Descartes showed a strong interest in the Rosicrucians, stating, “This society of scholars promises humanity new wisdom—that is, a true science yet to be discovered.”

The Room by the Fireplace and the Philosopher’s Life

Around this time, Descartes was leaning toward a kind of mystical symbolism regarding issues of natural philosophy and metaphysics.
His notes from that time contain expressions such as: “There is but a single active force within things—namely, love, mercy, and harmony… All material forms are animated by harmony. There are more moist and cold things than dry and hot ones. Otherwise, the active force would prevail too quickly, and the world would not have lasted long.”
However, while staying in a village on his way back to the army after witnessing the Emperor’s coronation, Descartes had a revelation. He came to believe that scholarship based on books compiled from the opinions of many people was unnecessary; rather, knowledge derived from the innate reason of a single person of integrity, who deduces the reality before his eyes, is closer to the truth. As examples, he noted that a city designed by a single person in the wilderness could be superior as a whole to the irregularity of a naturally formed city, and that a simple and clear law established by a single legislator could be better than a collection of customary laws. This revealed his confidence that true scholarship must possess internal and logical unity, and that a new philosophy would be best if it began with Descartes himself.
Thus, Descartes continued his reflection and established a method of scholarship and a guiding principle for his life, but he judged that it was still too early to decide on the foundations of philosophy and, in effect, continued his intellectual wanderings for the next nine years.
Reading the Discourse on the Method reveals how Descartes envisioned his life. The first stage consists of his studies at the academy and the insights gained through his entry into society (Part I); the second stage is the period when he first resolved to become a philosopher at his lodging in Germany and established his method and way of life (Parts II and III); and the third stage is the process, nine years later in the Netherlands, of building upon metaphysics to develop natural philosophy and human philosophy.
Among these, the second stage is interpreted as a period of reflection in a “room with a fireplace” in Germany. This was a decisive period for Descartes; over the course of several months beginning in October 1619, he first generalized the analytical method and formalized it as a procedure for acquiring all kinds of truth (summarized in four rules). Second, in mathematics, he intuitively grasped a new correspondence between geometry and algebra, thereby obtaining the key to analytic geometry; as a result, problems that had previously remained unsolved were successively resolved. Third, he resolved to devote himself to preparatory work aimed at solidifying the foundations of his future philosophy.
In addition to theoretical reflection, Descartes also conceived of a code of conduct—that is, a way of life as a philosopher of the new method. This is the famous “Provisional Ethics” found in Part III of the Discourse on the Method. The idea is to establish provisional guidelines for living well in the real world even while dismantling and reconstructing scholarship.
The Provisional Ethics is explained by three principles. First, to follow the customs of the country in which one was born and the religion in which one was raised from childhood, while respecting the views of moderation; second, to make one’s own decisions clearly, despite this; and third, for the sake of the goal of a scholarly life, to “always strive to conquer oneself rather than be conquered by fate, and to strive to change one’s own desires rather than the order of the world”—that is, to set the goal of overcoming oneself.
The first two principles reflect what Descartes had come to realize about the world: namely, that differences in lifestyle among nations stem not from nature but from artificial habits, and that individual decision-making is necessary in practical life. In particular, the third maxim emphasizes a goal-oriented life as a preparatory attitude for scholarly pursuits.
Descartes believed that the method of analysis could also be applied to moral issues. Analysis is a synthetic procedure in which one examines the truth or falsity of a given proposition, investigates its premises to arrive at a first premise that is clearly recognized as true, and then proceeds step by step, using that first premise as a starting point. The answer obtained in this way may result in either affirming or denying the original proposition in question. Therefore, he viewed provisional morality as a kind of problem and believed that future philosophical inquiry could trace back to its premises and ultimately lead to a “definitive morality” that either affirms or denies provisional morality.
Descartes’ reflection here is very lucid. He viewed his path not only as a way to securely acquire all knowledge but also as a way to securely acquire the practical good that he could control. Plato, too, applied the method of analysis to the entirety of wisdom, calling the principles reached through that method “Ideas,” and held that the Good must stand at the pinnacle of these Ideas; Descartes’s line of inquiry can be seen as an extension of this.
Looking at the entire process by which his system took shape, Descartes’ philosophy was developed over the course of his “room with a fireplace” period, his stay in Paris, and the several years following his move to the Netherlands. However, when discussing the foundations of Descartes’ philosophy, it is difficult to go beyond speculation regarding his early period, for which records are insufficient. Therefore, what first comes to mind is Beckman’s naturalistic way of thinking, which served as the starting point for Descartes’ reflections on the Method in the “room with a fireplace.”
The key insight Descartes gained from Beckman was that atomic thought enables the application of mathematics to the understanding of the world. By conceiving of an objective world of atoms with geometric properties—beyond the world perceived through the senses—Descartes was able to apply mathematics, the only discipline recognized as self-evident, to a new and broader domain.
However, for Descartes, the objective material world held far greater significance than it did for Beckman or Galileo. He did not view the objective world as a hypothetical construct corresponding to sensory facts, but rather as something known directly by the intellect without the aid of the senses. He regarded geometry as, in and of itself, a means of understanding the material world, even though it does not require experimentation. In this respect, Descartes was closer to Kepler than to Galileo.
In fact, during his stay in Paris after 1625, Descartes devoted himself to geometric optics rather than mechanics, discovering the laws of refraction of light; he stated that he regarded Kepler as his mentor in optics. Light was also the central theme of his Discourse on the World, completed in 1633.
Plato argued that one could grasp the objective essence of the world without waiting for experience, citing as evidence the soul’s memory of having seen reality before being born into this world. Descartes’ corresponding view was that God had implanted true ideas within our souls. True ideas refer to those that correspond to objective reality.
The fact that Descartes stated in his early works that “the seeds of knowledge lie within us,” and that in the Discourse on the Method, when discussing cosmology, he expressed that “God has firmly established these things in nature and, at the same time, firmly imprinted their ideas in our minds,” demonstrates precisely in this sense that innate ideas form the foundation of Descartes’ metaphysics.
Furthermore, it is presumed that Descartes came into contact with the Augustinian theological tradition during his stay in Paris. As a result, another element coexisting with Platonic intellectualism emerged in his philosophy. That is, the significance of the will began to emerge as an issue alongside that of the intellect.
The first point of contention was which of the intellect and the will should be held in higher esteem with regard to God Himself. God has implanted truth within our minds, but the archetype of truth also resides in God’s own intellect. This raises the question: Is this divine truth not subject to God’s will, or is it freely determined by God’s will?
Descartes held that God not only implanted truth in our minds but also freely determined that truth. He took the position that even rational truths are the result of God’s free creation—arguing, for example, that if God had wished, He could have made it so that “2 plus 2 does not equal 4.”
Second, the problem of free will exists directly within ourselves as well. The existence of our free will is a marvel in relation to God’s providence, and Descartes regarded this as a miracle. He viewed God as having accomplished three miracles—creation ex nihilo, free will, and the divine-human union—and how to understand these miracles had been a major theological issue since Augustine.
Like Beckman and Galileo, Descartes sought to grasp what lay beyond the sensory appearance of nature through mathematics and geometry, and he sought to adopt an atomistic view in the broad sense. However, what set him apart in this regard was his attempt to find in Platonism the basis for asserting that the material world depicted mathematically is reality itself. In other words, he sought to grasp the atomistic world as direct reality through the intuition of the intellect.
Therefore, it was first necessary to fundamentally critique knowledge that relies on the senses or the imagination. This is precisely what is known as “skepticism” (methodological doubt). Descartes believed that this skepticism must be carried out in a bold and fundamental manner, and that if there was even the slightest possibility of falsehood in any method of cognition, the entire method must be regarded as false.
However, the “I” that doubts this falsehood must be something in itself. It must be something that is necessarily acknowledged. In this way, the first principle—“I think, therefore I am”—was derived.