Descartes is generally regarded as the founder of modern western philosophy, and he was the first to establish a complete philosophical system. Philosophically, Descartes is a dualist and a rationalist. Descartes believes that human beings should be able to use mathematical methods-that is, rationality-for philosophical thinking.

He thinks that reason is more reliable than sensory feeling. He gave an example: when we dream, we think we are in a real world, but in fact this is just an illusion. He found four laws from logic, geometry and algebra:

Never admit that anything is true, and what I have no doubt about is taken as truth;

Every problem must be divided into several simple parts to deal with;

Thought must be from simple to complex;

We should make a thorough inspection from time to time to ensure that nothing is missed.

Descartes applied this method not only to philosophical thinking, but also to geometry, and founded analytic geometry.

Therefore, Descartes first thought that doubt is the starting point, and the knowledge of sensory perception can be doubted, so we can't trust our senses. So he won't say "I see therefore I am" or "I listen therefore I am". From this, he realized a truth: what we can't doubt is "our doubt."

Meaning: What we can't doubt is the "doubt itself" when we "doubt" this matter. Only in this way can we be sure that our "suspicion" is true, not a fake. Anyone who takes it for granted or takes it for granted is puzzled, so he introduces the famous philosophical proposition-"cogito ergosum".

Descartes regards this as the most basic starting point in metaphysics, from which it is concluded that "I" must be something independent of body and thinking. Descartes also tried to prove the existence of God from this starting point.

Descartes thinks that we all have the concept of perfect entity. Because we can't get a perfect concept from an imperfect entity, we must have a perfect entity-God-to get this concept.

Starting from these two points, Descartes continued to infer that since the perfect thing (God) exists, then we can be sure that the previous demon hypothesis cannot be established, because a perfect thing cannot allow such a demon to deceive people, so we can determine that "this world really exists" through constant doubts, and the mathematical logic after proof should be correct.

In the real world, there are many characteristics that can be rationally perceived, that is, their mathematical characteristics (such as length, width and height). When our reason can clearly recognize a thing, then it must not be illusory, but it must be what we know.

Although Descartes proved the existence of the real world, he believed that there are two different entities in the universe, namely, thinking (mind) and the external world (matter), both of which come from God, and God exists independently. He believes that only man has a soul, and man is a binary being, who can think and occupy space. Animals belong only to the material world.

Descartes emphasized that thought is beyond doubt, which had an important influence on European philosophy. I think, therefore, the controversy I caused lies in the so-called existence of God and animal monism (chimpanzee, octopus, parrot, dolphin, elephant, etc. Are proved to be intelligent), and the main idea of doubt is really helpful for research.

Two. Contribution to Mathematics and History

Descartes' most important contribution to mathematics is the creation of analytic geometry. Descartes succeeded in connecting algebra and geometry which were completely separated at that time. Descartes proved to the world in his book Geometry that geometric problems can be reduced to algebraic problems, and geometric properties can also be discovered and proved through algebraic transformation.

Descartes introduced the concepts of coordinate system and line segment operation. Descartes' achievements in mathematics provide a solid foundation for future generations to engage in calculus, which is the cornerstone of modern mathematics. He creatively transformed geometric figures into algebraic equations, thus solving geometric problems by algebraic methods, which is today's analytic geometry (or "coordinate geometry").

In addition, many mathematical symbols used now are first used by Descartes, including known numbers A, B, C, unknowns X, Y, Z and so on. And the representation of the index. He also discovered the relationship between the edges, vertices and surfaces of convex polyhedron, which was later called Euler-Descartes formula. He also discovered the Cartesian branch line, which is common in calculus.

In physics, Descartes also made some achievements. He put forward the theoretical demonstration of the law of light refraction for the first time in Refractive Optics. He also explained the causes of people's visual impairment and designed a kind of lens to correct their vision. In mechanics, Descartes developed Galileo's theory of motion relativity, emphasizing the linearity of inertial motion.

Descartes discovered the original form of the principle of conservation of momentum (Descartes defined momentum as scalar, not vector, so his principle of conservation of momentum was later proved to be wrong). He also developed some theories, such as universe evolution theory and vortex theory. Although there are many defects in the specific theory, it still has an impact on future natural scientists.

He also used the refraction law of light to explain the rainbow phenomenon, and analyzed the color through the rotation speed of elemental particles.

In psychology, Descartes also made some contributions. His views and great discoveries had a great influence on later psychology. He is a famous representative of modern dualism and idealism theory. His great discovery of reflection and reflex arc provides an important basis for the assertion that animals are machines. And put forward the hypothesis of response stimulus.

However, Descartes' concept of reflection is mechanical. He emphasized the difference between humans and animals. Animals have no hearts, but humans have hearts. This inference is a typical manifestation of dualism.

In addition, the theory of psychosomatic resonance is another typical expression of Descartes dualism in the relationship between body and mind. He believes that the human body is composed of material entities, and the human mind is composed of spiritual entities. Mind and human body can influence each other, cause and effect each other and interact with each other.

He believes that there are six kinds of primitive emotions: surprise, love, hate, desire, joy and sadness, and other emotions are branches or combinations of these six kinds of primitive emotions. ?

Although Descartes' dualistic psychology thought was wrong in theory, it played a very promoting and progressive role in the social background at that time. He used dualism to get rid of the absolute control of theology on science and guided people's thoughts to rational thinking and concrete research. Therefore, his contribution to psychology can not be ignored.

Extended data:

brief introduction

Rene descartes (French: rene descartes, also translated as Descartes; 1March 3, 5961-1February 650 1 1), a famous French philosopher, mathematician and physicist. He made an important contribution to the development of modern mathematics, and was known as the father of analytic geometry because he formulated the geometric coordinate system.

He is a representative of dualistic idealism and rationalism, leaving a famous saying that "I think, therefore I am" (or translated as "thinking is the only certain existence") and putting forward the idea of "universal doubt", and he is the founder of modern western philosophy. His philosophical thought deeply influenced the later Europeans and opened up the European rationalism (rationalism) philosophy.

References:

Baidu Encyclopedia-rene descartes