Fundamentalism is the mainstream of western modern epistemology since Descartes. In Descartes' view, the fundamental task of epistemology is to find a solid and reliable foundation for human knowledge, so as to build all the buildings of human knowledge on it. As long as the foundation is solid, the authenticity or correctness of human knowledge will be guaranteed. Descartes' proposition is to find an absolutely correct and unquestionable first principle first, which is the foundation. Then all human knowledge is deduced according to the rules of deductive logic. Logical reasoning is to deduce the conclusion of inevitability from the premise of inevitability. In this way, as long as epistemology provides a reliable foundation and an effective logical tool, the knowledge of the whole mankind is absolutely correct. Hume's skepticism and fundamentalism have the same starting point; Knowledge is a summer that needs a solid foundation. Unable to find such a basis, Hume was desperate and reached a skeptical conclusion.

Epistemological foundationalism is a metaphor from the construction industry. The fundamental weakness of this metaphor is that if the foundation is unstable or shaken, the whole knowledge building may collapse. So Descartes' task in constructing human knowledge focuses on one point: what kind of knowledge can become the first principle? How do we realize the first principle of absolute reliability? Hume and Becquerel argued forcefully that if human knowledge is a building, it is built on sand and will collapse at any time.

Peirce acknowledged the validity of Becker and Hume's argument, but neither accepted its premise nor its conclusion. Peirce thinks that we actually have knowledge and the task of philosophy is to explain how knowledge is possible. It is a bad metaphor to regard knowledge as a building that starts from the foundation and depends on it. The abolition of architectural metaphor led to two far-reaching epistemological conclusions in the 20th century. The first conclusion is anti-foundationalism: since knowledge is not architecture, epistemology does not need to find a solid foundation; The second conclusion is fallibility: because knowledge is not a building built on a solid foundation, human knowledge is always fallible.

In the view of foundationalism, knowledge is a static system composed of propositions, just like a building. Even if it is not completed, the future things will only add bricks and tiles, and the completed parts need not be changed. In Peirce's view, knowledge is a dynamic inquiry process. The so-called research refers to all human cognitive activities, so Peirce called his epistemology a theory about research. Peirce compared the research process to the Long March towards truth, the destination of the Long March is truth, and truth is the infinitely distant destination of the Long March. On the road of the Long March, there will never be a hard stone road under our feet, and our feet will be submerged. The only thing we can be sure of is that in this boundless swamp, there is always somewhere that can afford us. This is the only thing we can be sure of. It is precisely because of the fragile foundation that we are forced to keep moving forward and get closer to our goals. Only doubt and uncertainty urge us to seek new knowledge. This is Peirce's metaphor for the Long March. According to this metaphor, as long as there is a relatively solid land under our feet, we want to stop and rest. Once the ground under our feet can't bear it, we have to move on. The exploration of solid pavement is endless. Peirce said: "Science is not based on facts. It walks on the swamp. We can only say that this land is still strong, and we will stop here until it begins to shake. " ([1], page 589)

Peirce replaced the basic metaphor with the new metaphor of the swamp long March, thus fundamentally changing the task of epistemology. After Peirce, many philosophers looked at knowledge in the same way, but some of them didn't know Peirce's work. These anti-foundational philosophers include Russell, Wittgenstein, Pope, Newrat and Xia Pier. Of course, some are not thorough enough. Newrat has a similar metaphor: scientists are like sailors, they have to repair their ships in the boundless sea. They have no dock to dock at. During the repair process, every board on the ship can be discarded, but not all boards are discarded at the same time. [2] The two metaphors of Peirce and Newrat have the same meaning; We should not go out of the boundary of our actual knowledge and look for something similar to Archimedes point, so that our whole knowledge system can be demonstrated and evaluated according to this Archimedes point. The observation point (foothold) we can find is the observation point of our practical knowledge, which is as uncertain as other practical knowledge and often collides with unexpected and difficult experience. At present, Quine is one of the most famous representatives of this thought, and both Newrat and Pierce have had a direct influence on him.

Abandoning fundamentalism has two important meanings in epistemology. Descartes' hope of finding an absolute guarantee of reliable knowledge was dashed. In the future, epistemology need not look for that kind of guarantee. Second, we don't fall into Hume's skepticism at the same time. Only by accepting the basic metaphor can we find that there is no basis for skepticism. If we don't have independent observation points to demonstrate our whole knowledge system, then we don't have independent observation points to be the basis for us to deny the whole knowledge system. The only observation point we can get is provided by the knowledge we actually have. Within this knowledge framework, we can criticize or deny this or that belief individually, but we can't go out of this framework and deny all our knowledge. Global skepticism (universal skepticism, questioning everything) is as impossible as absolute certainty. Peirce put forward a view of knowledge that is neither absolutely certain nor doubtful: a non-dogmatic experimental attitude, which he called fallibility or "critical common sense". This is not a compromise or reconciliation of the first two propositions, but a complete denial of them.

The concept of "subject" is the core of basic epistemology, which Descartes called "heart". He argued that the human mind has a certain special ability, that is, the mind has a clear and definite understanding of itself, and the self-knowledge of the mind is the source and guarantee of human knowledge and the basis of human knowledge. 1868, Peirce published two articles "On Several Abilities of Man" and "Some Inferences of Four Inferences" in Speculative Philosophy Monthly, which reflected his attitude towards Cartesianism. The first article refutes the seven abilities Descartes gave to the mind one by one, and the second article focuses on demonstrating that the mind does not have four of them. "1. We don't have the ability of introspection, and all the knowledge about the inner world is based on our wrong reasoning about the outer world. 2. We have no intuitive ability, and every knowledge is determined by the previous knowledge logic. Without symbols, we have no ability to think. We know nothing about the absolutely unknowable. "([1], p. 265)

The first topic says that there is no special source of personal knowledge about one's inner world of consciousness. Descartes regards "self-thinking" as the initial and most basic starting point for acquiring external knowledge, and the knowledge I think or the self-knowledge of my mind is more direct and reliable than other knowledge. Peirce believes that although the mind is self-aware and this knowledge is very reliable, this knowledge is neither direct nor basic. Peirce believes that children will learn the word "I" only after they have acquired high language skills and learned a lot about the names of things in the outside world. Only when children are aware of their own intentions and emotions can they realize that they have an intentional and emotional self. For example, children may begin to believe that fire can be touched by hands. He touched the fire with his hand and got burned, so he realized his mistake and ignorance. However, it was not fire that made a mistake. The fire is already hot. Finally, the child realizes that there is a wrong self. All knowledge about external facts shows that there is a thinking and emotional self. "For an adult like me, his own existence is supported by all other facts, so it is much more reliable than any of those facts." ([1] p.237) Therefore, self-knowledge is neither fundamental nor absolute. Because they come from our knowledge of the outside world, on the one hand, they are as reliable as our knowledge of the outside world, on the other hand, they are no more reliable than our knowledge of the outside world.

Descartes believes that the mind has intuitive ability, that is, the first principle of acquiring knowledge through direct intuition requires the first premise without any premise. In other words, understanding should start from scratch. Peirce said that every kind of knowledge is logically determined by previous knowledge, and there is no unshakable and uncritical belief in our knowledge system. Therefore, the mind has no intuitive ability. A fundamental mistake of Descartes is to plant the bane of skepticism: if the first principle cannot be found, the result is skepticism. Descartes' opponent empiricism also made the same mistake. However, the first principle of empiricism is not rational intuition, but direct perceptual perception. Both of these foundationalism are unacceptable to Peirce. His groundless assumption about the first principle is unnecessary for the progress of knowledge.

The "I think" or intuition of the mind means that the most basic thought is the thought without language. Peirce pointed out that the mind does not have this ability to think without symbols. The so-called symbol refers to all meaningful things or things that can express meaning. Peirce put forward several arguments. First of all, there is no evidence to the contrary imaginable. If you want to refute this topic, you must find an unsigned thinking. So you must state that kind of thinking and express it in words. All the ideas that can be clearly identified support this assertion. ([1], P.25 1) Secondly, as a symbol, a symbol must be interpretable because it is meaningful. If we want to grasp the meaning of one symbol, we can only find other symbols. If we think through symbols, we can't surpass them. This topic has a very prominent position in modern philosophy. Because we can only think through symbols, the problem of meaning or interpretation has become the central issue of philosophy in the twentieth century. Philosophy of language, hermeneutics and structuralism all revolve around this issue. An important conclusion of contemporary meaning theory is that the content of thought is subject to the way of speaking. Different languages "splice" and cut the world in different ways, so different languages mean different ways of thinking. According to the Romance of the Three Kingdoms, Zhang Wen, an envoy of the State of Wu, and Fu Qin, a scholar of Shu and Han, fought. Use the words in the Book of Songs to prove that heaven has ears and feet, saying that heaven has a surname: Tian is surnamed Liu, because "the son of heaven is surnamed Liu". This way of thinking is determined by the linguistic characteristics of Chinese. Communication, understanding and comparative evaluation between different viewpoints, theories and cultures must be carried out through language translation. Feasible translation procedures determine the possibility of comparative evaluation. Therefore, Quine's inaccurate translation principle is a heavy blow to basic epistemology.

These three arguments can reinforce each other. According to Peirce's reasoning theory, the conclusion should not depend on a single deductive chain, but on a series of parallel reasoning chains, forming a thick reasoning chain. Perhaps each of these chains is weak in isolation and cannot make the conclusion reliable, but they can make the conclusion strong through aggregation and mutual reinforcement. ([1], p. 265) Wittgenstein used a similar metaphor in his philosophical research. Among these three themes, the third is linked with the second, which strengthens the first and second themes. Its strong argument for the first theme is that there is no pure private source of knowledge. Any language (the use of symbols) presupposes a subject group that can use and understand the same symbols-* * * homographs, and each symbol can only become a symbol if it can be explained. If any thinking must take the form of symbols, then there is no pure private internal knowledge, and there is no introspective belief that cannot be confirmed and corrected by the same person. The third topic also reinforces the second topic. The second topic presupposes that all knowledge should take the form of reasoning, so it should take the form of symbol chain. At the same time, the third topic shows the indirectness of knowledge: knowledge about things should be based on symbols representing those things. So there is no direct and correct knowledge, and there is no foundation of knowledge. There are two points that are particularly important here. One point is to emphasize * * * isomorphism, which is a key concept in Kuhn's later philosophy of science and hermeneutics. It can be said that homonym is the only possible form of objectivity, and we can't have other objectivity. The second point is to deny the possibility of private language, which is consistent with Wittgenstein's later period. Modernist philosophy leads to the possibility of private language, while contemporary philosophy mostly admits that private language is impossible.

Second, fallibility and critical common sense.

In the manuscript of 1897, Peirce summed up his absurdity theory as follows: "There are three things that we have no hope of getting through reasoning, namely absolute certainty, absolute accuracy and absolute universality." ([3], p141)1910, he added, "I don't admit that we know anything with absolute certainty." ([4], p. 108) To sum up, fallacy is such a topic: every proposition or belief in our knowledge system is not absolutely true (or not absolutely true), and it may be criticized and revised.

Someone may immediately give a counterexample: 2+2 = 4. Peirce replied that anyone who really doubts this proposition must be stupid; However, it would be even more foolish if he came to the conclusion that we absolutely know that 2+2 = 4. We often make addition mistakes, and what happened may happen again. 2+2 = 4 only counts the number of times when you are poor, and you can't guarantee that you haven't answered every time. The meaning of this sentence is that a certain number n is the minimum number of repetitions enough to produce certainty. In other words, if we repeat N- 1 times, we are not absolutely sure, but if we repeat it again, we will. This is obviously absurd.

Meanwhile, Peirce added that he had no doubt that 2+2 = 4. Isn't this a contradiction? No. This just shows that we don't have only two choices: fundamentalism and skepticism. Just because we don't doubt a proposition at all now doesn't mean that we will never be doubted. Any proposition may be doubted, but there must be specific reasons for doubting any proposition, which is the core of fallibility.

When there is no concrete evidence, we don't doubt one proposition, but concentrate on solving the evidence-based doubts about other propositions. This proposition implies a theory of criticizing common sense. Peirce did not make specific provisions (definitions) on critical common sense. Peirce put forward a slogan in What is Pragmatism (published in Monism 1905), which expressed the basic meaning of criticizing common sense. The six characteristics of critical common sense published in the same magazine lists some statements, such as unquestionable propositions and initial and non-critical beliefs; They may change over time, but very slowly; They believe by intuition rather than by reason; They are essentially vague beliefs. Peirce said in the article "Several Inferences of Criticizing Common Sense": "The sign of criticizing common sense is that he highly respects doubts, and he can almost be said to be a hungry Askra Farms. His hunger and thirst are not satisfied by ordinary doubts. He must have precious metals or other beliefs. " ([1], p.5 14) As Peirce did not give a clear definition of critical common sense, nor did he explain why he called it critical common sense, we can only guess why he used this statement. Peirce thinks that there is no essential difference between scientific research and common sense. Everyone's knowledge is based on the accumulation of existing knowledge, and a critical discussion is conducted on this premise. As far as common sense is concerned, we always have some beliefs. We never doubted them or even realized that we had those beliefs, so we believed them instinctively. There is no doubt that they are the starting point for further understanding, but they are different from the original principles obtained through reason. So this is a common sense attitude. Although it has not been doubted, it does not mean that it cannot be doubted, nor does it mean that it is absolutely correct. We can't treat them the way Descartes treated first principles. As long as there is evidence, we can doubt any of these beliefs. This is a "critical" attitude towards common sense (but not a general doubt), so Peirce's common sense is critical common sense.

Wrong and critical common sense is of great significance, which protects epistemology from Cartesianism. Descartes began to doubt everything and went to dogmatism, leading to skepticism. Peirce saved us from complete doubt and dogmatism.

The first inference of common sense can also be mistaken and criticized, that is, philosophy (knowledge reconstruction) cannot proceed from comprehensive and universal doubts, and we cannot acquire new knowledge without presupposing some previously acquired knowledge that we do not doubt. It is also psychologically impossible to fully doubt. When we are doing research or exploration, we already have a belief network, some of which were obtained before. We didn't think to doubt them, because we didn't realize that they could be suspected, or even that they existed. Peirce called existing knowledge "prejudice". This word generally contains derogatory meaning, but in Peirce's philosophy, it does not contain derogatory meaning, but is an indispensable prerequisite for knowledge progress. The usage of this word in Peirce's philosophy is very similar to that in hermeneutics decades later.

Peirce said: "We can't start with total doubt. When we enter the study of philosophy, we must start with all the prejudices we actually have. These prejudices can't be driven away by a single line, because they are things we didn't expect to doubt. Therefore, the initial doubt (total doubt) is only self-deception, not real doubt; ..... let's not pretend to doubt what we don't doubt in philosophy. " ([1], p. 256)

The second common sense epistemological inference that can be wrongly criticized is that epistemology or epistemology discusses knowledge not as personal subjective inevitability, but as objective validity belief. Knowledge is social, and cognition is social activity. Knowledge does not lie in any individual's subjective feeling of certainty, but in the consensus of researchers, and should be judged according to their ability to withstand public criticism. "In science, people agree. After a theory is put forward, it must be tested until an agreement is reached. After reaching an agreement, the question of certainty is superfluous, because no one doubts it. Individuals have no reason to expect the ultimate philosophy we pursue. We can only pursue it as philosophers. " ([1], p. 265) Peirce advocates common sense, because common sense does not doubt everything, but always carries a prejudice net. At the same time, he advocates fallibility, and every belief can be criticized, so his common sense is critical. Concepts such as fallibility, common sense and isomorphism can naturally lead to the theory of evolution of scientific knowledge. In this respect, Peirce and Pope are in the same strain. Peirce's understanding of evolution is reflected in his views on truth and scientific methods, which is also very similar to Pope.

Third, scientific methods and scientific progress.

1877, Peirce published the article "Determination of Belief" in Popular Science Monthly, which was the first in a series of articles on "Liberation of Scientific Logic", and expounded his views on scientific methods.

Since the Determination of Belief, Peirce has adopted a Darwinian position: man is a member of the animal kingdom; Human action is a kind of physiological operation, which points to the best adaptive relationship between organisms and the environment. Science is a human activity, so it is a form of adaptation. Of course, as a special form, it has its special content. Peirce said that research is a struggle to end doubts and gain beliefs. ([1], p. 374) The so-called belief is the knowledge that we think is the truth (in fact, it is not necessarily the truth), and this knowledge is often expressed through propositions. Peirce denies thinking without symbols, so all beliefs should take the form of symbols. When you gain faith, your doubts are over, and your research is over. Doubt and belief are two psychological categories. This research activity can also be defined by the physiological state of the brain and central nervous system. Faith (belief) is a state in which our behavior is dominated by stable habits, and it is "a state in which we will take specific actions on specific occasions". ([1], p. 373) Suspicion is an unstable state, habits are broken and practice is hindered. However, this state stimulates us to take action to eliminate anxiety. Because faith is something that people are prepared to act, and it is a potential practical activity, which interacts with the environment, so faith obeys natural selection.

If research activities are regarded as the adaptive process of organisms, then the basis of judging various research methods is their actual effectiveness in eliminating doubts and establishing beliefs, and the best method is the most adaptive method. The most adaptable method can promote researchers to adapt to the environment in the long-term competition with other methods, so as to survive. Peirce thinks that the scientific method is the most suitable for the environment, so it is superior to other methods.

Peirce classified the existing research methods or methods to determine beliefs into four types, namely, conservative methods, authoritative methods, transcendental methods and scientific methods, and analyzed their evolutionary adaptability one by one.

The persistent method (or translated as stubborn method) is a personal method: stubbornly believe everything you already believe and refuse to make any changes to your existing beliefs, regardless of the environment. This method can protect the stability of belief in a short time, but it is obviously not suitable for the environment. "Society impacts it, and people who adopt it will find that others have different ideas from him. When he is wiser, he will think that other people's opinions are as good as his own. This will shake his firm attitude towards his beliefs. ..... Unless they live in seclusion, they will inevitably influence each other in their views. Therefore, the key is how to determine beliefs by the same person, not by individuals. " ([1], p. 378) The authoritative method is to let the national legislation stipulate all beliefs, instill them systematically, let the people know nothing that causes suspicion, and punish those who spread different views. This method was practiced in ancient Egypt and medieval Europe and was very effective in some places. But this method will not be effective for a long time, because no country can legislate for public opinion on all issues. For many problems, individuals will certainly form their own views in a way different from the official regulations. Moreover, when different * * * identical bodies are in contact with each other, some people will find that the same method produces opposite opinions in different * * * identical bodies, which leads to doubts about authoritative methods. Transcendental method, also called rational method, refers to Cartesian method. Philosophers are the main obstacles to rational methods. They only believe in reason or logic, and reason from the concept of pure reason, and have made some achievements. However, the transcendental method has not produced a lasting consensus, because each generation has discovered something different from its own reason. In addition, rationalists always stay away from empirical facts. So this is not an effective way to generate long-term stable beliefs.

The third method has a * * * defect, and the beliefs they lead to are not determined by the facts themselves, but by the temporary individual and collective prejudice. A stable belief must be determined by something stable, and something stable can only be an external reality. "We must find a way, according to which our beliefs are not determined by anything man-made, but by external persistence-something that our thinking can't influence." ([1], p. 384)

The scientific method is the best method: "Its basic assumption is that ... there are some real things whose characteristics are completely independent of our views;" Those really inspire our feelings according to the law. Although our feelings are as different as our relationship with objects, we can determine what things are actually by using the law of perception for reasoning. Anyone who has enough experience and sufficient reasoning will come to the only correct conclusion. "([1], p. 384) The scientific reasoning advocated by Peirce is called hypothetical reasoning. Faced with environmental problems or suspicious beliefs, we put forward theories or hypotheses through research. The new hypothesis is a new action plan. If it leads to failure, it will be refuted. We must find a new hypothesis. If it leads to success, it will pass the test and our belief will be temporarily determined. This hypothetical reasoning is the main content of Peirce's scientific method. Peirce's scientific method is basically the same as Popper's guess refutation method. Peirce has long pointed out that we learn more from refutation than from confirmation. It is by forming wrong views and letting them be tested by experience that we gradually approach the truth. Active scientists "love highly unreliable hypotheses and praise them temporarily." "Why did he do that? Just because any scientific proposition is always easily refuted, it will flourish or decline. ..... The best hypothesis, that is, the most popular hypothesis among researchers, is the hypothesis that can be refuted most heartily if it is false. This is much more valuable than small advantages such as seemingly credible. " ([3], p. 120) Peirce believes that every wrong hypothesis will be refuted sooner or later if it is thoroughly tested by science. The coincidence with observation does not prove that the guess is right; But if you guess wrong, you will eventually show your true colors. "([3], P. 12 1) It is precisely because of their critical attitude towards scientific conclusions that scientists constantly carry out experimental tests, thus getting closer and closer to the truth. The second half of hypothetical reasoning is to deduce predictions from assumptions and test them with experiments, which Peirce calls induction. The reasonable basis of this induction lies in its self-correction tendency: "We should not ignore the self-correction tendency in the process of induction, which is its essence and its miracle. The possibility of its conclusion is only that if the truth rate sought is not reached, the expansion of the induction process will lead to a closer approximation. " ([5], p. 729) Therefore, from a long-term point of view, scientific methods will gradually lead us to truth and to "things that are independent of thoughts or opinions of anyone"; ([1], P.2 1 1) leads to the consistency between abstract statement and ideal limit, and endless research will bring scientific belief closer to that limit. "([1], p. 565)

Some scholars believe that Peirce adopts different evaluation criteria: the first three methods judge from the perspective of evolution according to their effectiveness in generating stable beliefs, and the fourth method judges according to their relationship with truth; The former is descriptive and the latter is normative. At least, in Darwin's theory of evolution, evolution has no predetermined purpose. Peirce's view is inappropriate. Firstly, Peirce made a unified evaluation of the four methods from the perspective of evolution; Secondly, although biological evolution has no predetermined purpose, research activities are conscious and purposeful. Pierce never completely copied Darwin's theory. .