He is considered the founder of modern psychology and mathematics: Who is Descartes?

Name Surname: Descartes

Date of Birth: March 31, 1596

From: La Haye, France

Professions: Philosopher, Mathematician

Died: 11 February 1650

French thinker, writer, scientist, and mathematician. He is regarded as the founder of modern psychology and mathematics. He played a major role in bringing science to its present level with his theories that inspired scientists and philosophers after him. Benefiting from mathematical expansions in the intellectual field, he argued that there is certain absolute-absolute information that emerges directly and is indisputable; He put forward this argument with his famous saying “I think, therefore I am”. Considered one of the main actors of the scientific revolution, Descartes contributed greatly to the evolutionary process of plane geometry and mathematics by developing the "Cartesian coordination system" (Cartesianism).

René Descartes (31 March 1596 – 11 February 1650)  was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathematics was central to his method of inquiry, and he connected the previously separate fields of geometry and algebra into analytic geometry. Descartes spent much of his working life in the Dutch Republic, initially serving the Dutch States Army, later becoming a central intellectual of the Dutch Golden Age. Although he served a Protestant state and was later counted as a Deist by critics, Descartes was Roman Catholic.

Rene Descartes was born to a wealthy family on March 31, 1596, in France, in La Haye, which is now named after him and is part of Indre-et-Loire. After his mother died of tuberculosis a year after his birth, he was raised by his stepmother. At the age of ten, he was sent to a Jesuit college named Royal Henry-Le-Grand in La Fleche, Anjou, which he would later describe as one of the best schools in Europe. Due to his poor health, he was prescribed by his teachers to go to boarding. Since he was allowed to stay in bed until he felt better, he concentrated on math studies, which he was very interested in. Since the education given at the school focused on Latin and Greek, there was an opportunity to learn these languages well; therefore, in the future, he saw great benefit from this education in his examination of old scientific and intellectual works.

Descartes, who was very interested in traveling, seeing new places, and learning new things, went to Paris in 1612 with a few of his friends after graduating from high school. Fascinated by the majestic city, he lived recklessly for a while. Then, when he met two of his friends who were also interested in mathematics, he followed their purpose of coming to the city and plunged into scientific research. During the period until his university education, he made research and studies on mathematics non-stop, especially with his friend Mersenne. While he was here, he met Mydorge, one of the famous mathematicians of the time, and broadened his horizons.

During his education, he developed himself, especially in the fields of classical literature, history, rhetoric, and philosophy. Under his father's direction, he entered the law school of the University of Poitiers and graduated in 1616. At that time, Europe was like a boiling cauldron. There were religiously based regional conflicts everywhere, and large numbers of defensive military units sprang up. Because of these political and social upheavals, young people from noble families joined the church or army; he also decided to join the army to consolidate his social status. Two years after graduating from high school, in 1618, when he heard exciting rumors about the Dutch Prince William of Orange and his expeditions to liberate his country from Spanish occupation, he followed the prince's invitation and settled there, in search of adventure and was eager to travel. He began serving in the Protestant Dutch army under Maurice, Prince of the United Provinces of the Netherlands (Nassau).

Descartes, who spent several years with this enlistment as a soldier, met Isaac Beeckman, who during his tenure was the person who would make him aware of his creative talents in mathematics and physics. He wrote "Compendium Musicae", one of his first philosophical works, in 1618 and dedicated it to Beeckman. In November 1619, during his trip to Germany, he developed his own vision of using mathematical knowledge to solve problems related to physics. Descartes' vision was to discover the foundations of the sciences that would make an excellent contribution to the development of humanity. This period was a turning point in the life of the famous thinker and was a process in which he formed the intellectual plane of the theories he would put forward on the development of analytic geometry. He would devote the rest of his life to unraveling the mysterious link between mathematics and nature. The philosopher, who also studied the concept of "free will" in St Augustine's (354-430), pondered on the theory that human will, which he equated with God's will, as a natural feature of creation, is independent of God's will.

After leaving the service of the Prince of Orange, Descartes, who traveled to some European countries such as Denmark, Poland and Germany for a while, returned to the army at the beginning of the Thirty Years' War, and this time he began to serve the Catholic Duke of the Bavarian army. While in Ulm on a military mission, he developed a methodology on the unity of the sciences. For Descartes, who did not enter into a hot battle during his military life, this period was a period in which he made gains only for thinking, traveling, researching, and producing, in "great laziness and messiness". The greatest aim of the thinker, who was increasingly interested in intellectual actions and various sciences, was to travel the world and reach concrete facts about the universe. That's why he traveled to many places throughout his life, took part in the army, tried to get along with people of different statuses and natures, gained experience in many subjects, and tested himself in different conditions. In November 1619, in a warm room with a fireplace, he had his famous dream, which he would later attribute symbolic meaning to and consider a turning point in his life.

In 1621, he began his military service in the Hungarian Imperial Army. In 1622, he returned to France and settled in Paris; He stayed in Britanny for a while. The following year, he went to Poitou with his family, sold all the estates he had inherited from his mother, and was able to spend the rest of his life in prosperity; he invested all his income (27,000 livres) in bonds to avoid financial difficulties while doing his research. The thinker, who made a trip to Italy in the same year, resided in Paris until 1627.

In 1628, he returned to the Netherlands, where he spent the most productive period of his intellectual, scientific, and literary genius until 1649. He produced groundbreaking theories, especially on mathematics, geometry, and philosophy; He made inventions and set about writing his famous book “Treatise on the World”. While there, he met Cardinal Berulle and benefited from his rich horizons to bring his intellectual theories to life. On the other hand, he corresponded with his friend Mersenne, with whom he never broke off, and exchanged ideas about his work. He maintained his friendship with Beeckman and communicated with scientists such as Mydorge, the great Frans von Schooten, Hortensius, and Huygens.

For the next two years, he took no matriculation exams at Franeker and Leyden but was not interested in getting a degree. Despite the fact that in 1633, the famous physicist Galileo was convicted by the Roman Catholic Church for his claim that the world was round and therefore trying to break down the church's false scientific beliefs, Descartes had completed "Treatise on the World", the product of four years of scientific work. However, he stopped publishing it (the book was published in 1701, many years after his death). In the same period, he finished the draft of “Le Mond”; but he did not publish it either.

Although Descartes did not marry throughout his life, a daughter named Francine was born to his Dutch lover, Helene, with whom he lived and who used to be his maid, in 1635. However, Francine's life was short-lived and she died in 1640, at the age of five. This death deeply shook the famous thinker.

Descartes continued to bear the fruits of his work, which focused on mathematics and philosophy and wrote and published many works of very high scientific value. In 1637, he published his work "Discourse" anonymously. In 1640, he published "Meditations". In 1643, the "Rules" found objectionable by the University of Utrecht caused the thinker to be condemned by local authorities for containing elements of atheism. Two years later, the same university banned all biased/unbiased comments about the work and introduced a "neutral censorship" practice. At the same time, his long-lasting correspondence with Elizabeth, Princess of Bohemia, began. They exchanged ideas with the princess on many subjects from various branches of science to politics, especially mathematics, geometry, medicine, philosophy, and metaphysics. He published his book “Principles of Philosophy”, which he dedicated to the princess, in Amsterdam in 1644 (The work was translated into French in 1647). Then Descartes went to Paris, met with the famous mathematician and physicist Pascal, and had the opportunity to share his new works and views with him. Meanwhile, he turned down the offer of residence and annuity offered to him by the King of France in order to continue his work in an independent and flexible environment.

In 1649, he completed and published his book "The Passions of the Spirit". In November of the same year, he settled in Stockholm to give lectures to Queen Christina of Sweden, who was very impressed by his works and wanted to benefit from his genius and gave her a lecture on the subjects of which he was an expert. However, Descartes, who was used to getting up late all his life, was disturbed by the fact that the lessons were held quite early in the morning at the request of the queen. In addition, his body, which could not adapt to the extremely cold climate that he was unfamiliar with, became exhausted and caught pneumonia, and the famous thinker died on February 11, 1650, at the age of 54. His last words were, "Here it is, my soul, it's time to leave." Some researchers claimed that Descartes was also infected with the disease, as he nursed the French ambassador, Dejion A Nopeleen, who was being treated for the same disease. However, it was later revealed that the famous philosopher was weakened by poisoning due to his use of arsenic, according to the investigations of Doctor Eike Pies. Descartes' tomb was moved to his homeland, France, Paris in 1667.

Descartes overturned the intellectual accumulation of the West up to that time; He broke new ground with his thoughts that led to great developments in science and especially in mathematics. Religious domination, meaningless conflicts, and intolerant and bigoted attitudes towards modern ideas prevail; At the same time, he lived in a period when the intellectual, artistic, and cultural shell change of Europe took place. He accompanied the breakthroughs realized in many fields with his thoughts and works. He was among those who built the Renaissance of modern science, making the Middle Ages history. He underlined that despite the strong rise of the understanding of nationalism, humanity can meet on a common denominator on the axis of "scientific thought" and "reason". With the different and innovative perspective he brought to philosophy, he laid the foundations of modern philosophy.