Knowledge theory can never be produced in a vacuum. There are always psychological, economic, social and political conditions behind it, which are the driving forces of knowledge generation. The external factors that inspired Plato to construct his theory are obviously different from Descartes. Plato was followed by an aristocratic family, living in an era when the old aristocratic rule system gradually collapsed and the emerging business class and early democratic spirit began to appear. In the past two hundred years, the combination of social conditions and intellectual conditions gradually weakened the moral authority of the old aristocratic values. This value is based on the myths of Homer and hesiod. With the disintegration of the old values such as honor, loyalty and courage and the natural forces of aristocratic rule, the civilian values have replaced the old values. But Plato believes that this kind of civilian values is actually greed and thirst for power, and it is just a disguise. In the era of Socrates and Plato, these new values were taught by rhetoric experts called "wise men". In the eyes of Socrates and Plato, these people seem to be maliciously praising a world with different centers. In order to counteract the corruption of the wise and maintain the system that can prove the legitimacy of elite rule, Plato should not only attack the wise school, but also oppose Homer's authoritative position and replace it with pure reason. The aristocratic values embodied in Homer's works are exactly what Plato hoped to support, but Homer did not defend these values except using poetic words to arouse people's feelings. If Plato wants to defend these values rationally, he must replace the influence of poetry (embodied in Greek mythology and drama) with philosophy (that is, the spokesman of rationality). /kloc-Descartes in the 0/7th century faced not the opposition between poetry and philosophy, but the opposition between religion and science. Descartes lived in the period when new science was born. When Copernicus was born, he died only forty years ago. Descartes was contemporary with Galileo and Kepler. Newton was only eight years old when he died. In fact, Descartes himself discovered analytic geometry in his twenties and made great contributions to the development of science.
At that time, the growing power of emerging science had begun to challenge the declining authority of the church. The church ruled for thousands of years, but in the 200 years before Descartes was born, it suffered several major setbacks (internal division of various sects, falling out of favor with secular rulers, and the emergence of Protestant reform). The church is not only trying to maintain its political power, but also trying to protect the moral image of human beings. It is in this respect that the emerging science poses the most direct challenge to religious authority. 1632, the Inquisition arrested Galileo, tried him and found him guilty of blasphemy, and the conflict between the two sides reached a fever pitch. Galileo was arrested because he published an article in which he mentioned that Jupiter has four moons. People may not immediately understand why the idea that Jupiter has four moons threatens religious authority, which will be explained below.
The Galileo incident threatened the traditional view that for thousands of years, the concept of "nobility" of human beings was closely related to the idea that God created the Garden of Eden in the center of the universe (that is, the navel of reality), and the rest of the universe diverged from the Garden of Eden like concentric circles. According to this thinking, the drama staged by human beings is the core drama of the universe, and any other existence in the universe is arranged here only as a witness of human drama. The function of this concept is to give meaning to human behavior. Even if someone's life is full of misfortunes (there are many misfortunes in the Middle Ages), at least this misfortune is meaningful. Therefore, even the most miserable human living conditions have some nobility.
But now, this lofty concept of human life is suddenly threatened by Copernicus' theory. Copernicus thought that the earth was not the center of the universe, but actually the earth and other planets revolved around the sun (so Heliocentrism, not the geocentric theory, was correct). If the earth is just a celestial body flying in space and has no more or less significance to other celestial bodies in the universe, what does this discovery mean for the concept of "nobility" of mankind? (Freud once said that the nobility of human beings suffered three fatal blows: for the first time, Copernicus discovered that human beings were not the center of the universe; The second time, Darwin discovered that man is an animal; The third time, Freud found that the animal was sick. But there is a scientific fact that prevented Copernicus's radical theory from achieving great victory at that time. The fact that the moon goes around the earth is indisputable. If Heliocentrism is right, why does the moon go around the earth? Why doesn't the moon go around the sun, just as the earth should go around the sun? Now you can understand the significance of Galileo's discovery. If Jupiter's satellites orbit Jupiter, it proves that satellites can orbit planets that are not the center of the universe. This proof also disintegrated the last pillar of geocentric theory.
Similar to Galileo, Descartes found himself in an awkward position. He is a devout Catholic himself and doesn't want to have a conflict with the church authorities. But he has just finished a manuscript about physics, the world, and he knows that many chapters are consistent with Galileo's views. So instead of publishing this manuscript, he decided to write a philosophical work to create a harmonious atmosphere for intellectuals and reconcile science and religion. He wants to show that it is not contradictory to be a "scientist who believes in religion". He actually wanted to show that the possibility of science itself is based on some theological assumptions. He named the book "Meditation on the First Philosophy" and dedicated it to "the most knowledgeable and outstanding person: the dean and saint of the Paris Theological Seminary".
Descartes flattered the theologians in Sorbonne (the alias of Paris Theological Seminary) in his inscription, but in his letter to his friend Father Melsena, he used a completely different tone. "I want to say (and only between us) that these six meditations contain all the basic ideas of my physics. But please keep it a secret for me, because if they (theologians) know, they will not be willing to accept my point of view. "
In my opinion, Descartes successfully completed the task. As far as I know, there is no direct conflict between Catholicism and science here Descartes proved that this conflict is not inevitable. It seems to me that most of the religious opposition to scientific theory today comes from some Protestant camps (such as opposing the teaching of Darwin's theory of evolution). Protestants may still be waiting for their Descartes to appear.
Next, we discuss the epistemology established by Descartes in Meditations. Descartes announced his grand plan in the first paragraph of the book: "If I want to build a solid, reliable and lasting framework in science, I must completely and seriously get rid of all the views I accepted before, and then start over on this basis."
Please note that the key metaphor in this passage comes from carpentry. Knowledge is like a building, and all the superstructure depends on the foundation. How solid the foundation is, how high the building is. You will find that philosophers often develop their views around key metaphors. For example, you can think about the role of Plato's metaphor about the sun and shadow. ) Descartes continued.
From this, we can see the method used by Descartes, that is, the famous doubt method. There is a classic expression of doubt method: everything can be doubted (deonibus dubitandum est). This classic expression requires Descartes to doubt any proposition, as long as he can find even a little reason to doubt. Note that the method of doubt is different from that of the court, and it is reasonable not to ask for doubt; On the contrary, any possible doubt is enough to invalidate the proposition. All these doubts have a purpose, that is, to find something that is unquestionable, unquestionable and absolutely reliable. If this absolute certainty exists, it will be the foundation of the knowledge building.
I will move on and avoid anything I can imagine that is a bit suspicious, as if I knew it was absolutely wrong. I will continue on this road until I meet something reliable, or, if not, at least until I know there is nothing reliable in the world.
Descartes did not regard his rule "everything is suspicious" as a way of life. This rule is part of the philosophical game, but it is a serious game. The purpose of the game is to discover the foundation of knowledge, if there is a foundation to be discovered. If this foundation does not exist, people will give up games and return to real life. But when they come back, they will bring more cynicism than before playing this game, because they have "known" that there is no so-called knowledge, only opinions, rumors, prejudices and passions. The "knowledge building" is built on quicksand. Descartes' method is his own way to find a clear answer to the question whether the center remains the same.
Let's go back to the plan of meditation. Descartes continued.
Up to now, the most authentic and reliable things I have accepted are all obtained from or through feelings. However, I sometimes feel that these senses are deceptive; For the sake of prudence, we will never believe everything that has deceived us.
It can be seen that Descartes used a bulldozer, not a crowbar, when pulling out the decaying beam of the knowledge building. Since emotion is a well-known liar, we should thoroughly doubt it, that is to say, all beliefs based on emotion (after all, most beliefs are based on emotion) should be abandoned. However, Descartes suddenly suspected that he might have pushed the building demolition project too fast. He said:
However, although the senses sometimes deceive us on things that are not obvious and distant, there may be many other things. Although we know them through our senses, there is no reason to doubt them: for example, I am here, sitting by the fire, wearing an indoor robe, holding this paper in both hands, and so on. How can I deny that these two hands and this body belong to me, unless maybe I am compared with those crazy people. The brains of those crazy people are disturbed and covered by the black gas of bile, so that they often think they are kings, even though they are poor; Although I am naked, I often think that I am wearing red and gold; They fantasize that their heads are made of pottery, pumpkin or glass. However, they are crazy. If I compare with them, my absurdity will not be less than theirs.
This is rene descartes, sitting alone at the table in front of the fireplace in her pajamas. His stage is quite different from Socrates'. Socrates discussed philosophy in the streets of Athens and regarded philosophy as an essential social activity! Obviously, the concept of thinking has changed a lot since the Greek era. Descartes stared at his hand and thought, "This is my hand." How could he be wrong? Only a madman would stare at his hand and wonder if it was not his own. If you see someone sitting on the campus lawn after class, stare at their hands and say, "I'm not sure this is my hand." Don't say, "You are a philosopher!" And say, "psycho!" Descartes was fully aware of this, but under the limit of extreme skepticism, he really wondered if he was looking at his hand. (By the way, have you noticed Descartes' description of the crazy and wonderful Baroque: "... the cerebellum ... is such an uneasy and fuzzy black bile gas ...") Descartes went on to write:
In the meantime, I must remember ... I have the habit of sleeping. In my dream, there will be a madman doing exactly the same and sometimes even more absurd things when he is awake. How many times have I dreamed that I was in this place at night, wearing clothes by the fire, although in fact I was lying naked under the bed! ..... I remind myself that I am often deceived by these illusions in my sleep. After careful thinking, I can clearly see that there is no definite sign that can clearly distinguish between waking and sleeping, which can't help but surprise me.
Do you understand Descartes' view? Can you refute him? Can you come up with a test to prove that you are not dreaming now? Obviously, it is useless to pinch yourself (just like the characters in the comic book), because it is likely that you are pinching yourself in your dream. Similarly, you can't ask your neighbor, "Am I dreaming?" You may dream of her answer in your dream. In fact, Descartes seems to have left us at a loss, because the only way to refute him is to come up with a test that is impossible in a dream. But any exam method, as long as you can think of it, you can dream.