an illusion. Relativity theory may be an illusion. Scientific knowledge of quantum mechanics, geometry, chemistry, biology, sociology, and so on may be false impressions. All axioms and logic systems may be wrong. Especially what we call objective laws may be illusions. Kant proposed a Copernican revolution and believed that all so-called objective knowledge must be subjective.

We can believe that mankind has mastered many truths, but in the end it is impossible to judge what is truth. When it comes to any specific theory, we have no good reason to prove that it is objective truth. So we can only say that there is no absolute truth in the world. Descartes made us doubt everything, and Carl Marx's motto is also to doubt everything.

Popper pointed out that the conclusions obtained by incomplete induction are impossible to be confirmed. For example, all crows in the world are black is an inductive conclusion. After observing 10,000 black crows, there is no guarantee that the next crow is not white. All the human exceptional functions we saw are deceptive, but we cannot theoretically prove that there is no exceptional function in the world. Gödel's Incompleteness Theorem tells us that the biggest major premise of the deductive method cannot come from deduction but only from induction. Therefore, all our knowledge from deductive method is ultimately unprovable, and all science is built on the beach.

If our knowledge is illusion, then does scientific research have meaning? Yes. Scientific meaning does not come from objectivity, but from usefulness or practica- lity.

I am hungry now, I want to eat crabs. I want to know if crabs are poisonous. Popper told us: No matter what method you use, you can not prove crabs are non-toxic? Even if you have taken 10 bites, you can't guarantee that the 11th bite is non-toxic. You can not even prove rice non-toxic. So what should you do? Starve to death? This misunderstanding turned Popper's theory into a fasting theory. The responsibility of scientists is not to be miserable, not to sigh, and it is the responsibility of scientists to find a way out for humanity. Although Popper's conclusion is of great theoretical significance, what people need is more of a proof theory. If there is no absolutely confirmed theory, at least we need a relatively proven theory, although the relatively proven theory may cause poisoning, but people also willing to accept, because we do not want to starve to death.

Humans have been using relatively proven theories since ancient times. These theories will have a variety of errors, but they have great practical significance.They can only be perfected gradually and cannot be abandoned. There was hardly any truth in the earliest human hands. There were only some analogical revelations, most of which were wrong. Therefore, human survival ability at that time was very low. But it was such revelations that enabled them to survive and gradually grew stronger. The mistake of Dancy and many western scholars is that they did not consider the question of truth standard from the point of view of practice.