René Descartes (1596–1650)

Famous French philosopher; founder of modern western rationalist philosophy; great mathematician, physicist, astronomer, biologist and psychologist; founder of analytic geometry.

Descartes was born on 31 March 1596, in the city of La Haye en Touraine, France, into a noble family. His father was a counselor in the parliament of Brittany. In 1604, Descartes entered the Jesuit Collège Royal Henry-Le-Grand at La Flèche, and received traditional education. In addition to studying theology and scholastic philosophy, he also learned mathematics and some natural science knowledge, and was particularly interested in mathematics. In 1613, Descartes entered the University of Poitiers, where he earned his law degree three years later. After graduating from university, Descartes was uncertain about his career choice, and resolved to travel throughout Europe in search of wisdom in the “great book of the world”. In 1618, he left France to join the Dutch States Army as a civilian volunteer, and later entered the service of the Catholic Duke Maximilian I, Elector of Bavaria. After his discharge from the army, Descartes settled in Paris, France, where he concentrated on scientific research and tried to establish a new scientific system of his own. In 1629, he moved to Holland and lived in seclusion for 20 years. In 1637, Descartes published his first work, Discourse on the Method in French, and in 1641 Meditations on Metaphysics in Latin, which proved his philosophical view in a more systematic way. In 1644, Descartes published his systematic work Principles of Philosophy. In 1649, he finally published his psychological work Passions of the Soul.

Descartes was not only a philosopher, but also a natural scientist with great achievements, and he made important contributions to sciences such as mathematics, physics, astronomy, biology and psychology. In philosophy, Descartes upheld dualism in ontology and idealism in epistemology.

Like Bacon, Descartes attached great importance to the methodological question of scientific knowledge. Descartes thought that the past scholastic philosophy was just empty talk, which could only lead people into fundamental errors and could not bring about any real and reliable knowledge, therefore, a new philosophical theoretical system had to be established, using a new and correct method, which began the shift of philosophy from traditional ontology to epistemology. Unlike Bacon, who believed that the alternative to the method of scholastic philosophy was the inductive method of experience, Descartes advocated the deductive method of reason, with Euclidean geometry as the specimen. According to Descartes, in order to obtain the clearest and most intelligible ideas, which, like the “axioms” of geometry, have become self-evident “first principles” and thus the basis for the construction of an entire system of rational knowledge, it is necessary to eliminate all prejudices or ideas that have not been thoroughly examined by reason. This required “universal doubt”, a doubt that is different from the agnosticism which denies all knowledge, but only uses doubt as a means and method to seek and establish the knowledge which can not be doubted on the basis of universal doubt, so as to achieve the purpose of eliminating the false and retaining the true. In Descartes’ view, mathematics can be understood clearly by reason, so mathematical method can be used as a method of seeking truth, and mathematical methods should be used to find some of the most fundamental truths as the basis of philosophy. Descartes held that I can “doubt everything”, but there is one thing that is beyond doubt, that is, “I doubt” itself. I doubt is that I think, and since I think, then there must be a thinking I, that is, “the thinker”, which is the famous “Cogito ergo sum” (I think, therefore I am) thesis, which is the starting point and first principle of Descartes’ entire philosophical theory. Obviously, Descartes deduced my being from my thought, which is typical subjective idealism.

In epistemology, Descartes denied the reliability of the sense experience of objective things, held that the sensation obtained from the outside world through the senses is usually an illusion of confusion; only the fundamental principles based on rational knowledge, such as geometric principles, can have a clear necessity, which is the “innate ideas” inherent in the human mind. Descartes’ idealist thought of rationalism was criticized by the British materialist empiricist Locke.

Metaphysics, i.e., ontology, is an important content of Descartes’ philosophical thought. Descartes divided substance into infinite and finite substances. The former is self-caused, and this absolute substance is God; the latter is something that can exist only by relying on God and not on other things, and such relative substances are further distinguished as material and spiritual substance. The only essential attribute of material substances is extension, i.e., possession of space. What is extensive cannot be thought; and spiritual substances are not extensive and do not occupy space; therefore, the two are world-essences that do not interfere with each other and are independent of each other. However, this “dualism” encountered great difficulties in the question of human body and soul. Descartes put forward the “interactionism of body and soul”. He held that there was a “pineal gland” in the human body, and that the soul produced ideas of external objects and conveys them to the “animal spirits”, which in turn transmits them to the muscles through the nerves and blood vessels, causing bodily movements. His doctrine was criticized by Malebranche and Spinoza. Descartes died on February 11, 1650, in Stockholm, Sweden, after contracting pneumonia due to his inability to adapt to the cold climate of the north.