Much of Hegel's dialectics is actually epistemology, not logic. Most of the content in Engels' Dialectics of Nature is actually the world view, not dialectics, but the application of dialectics. Marx's Historical Materialism includes two parts: meta-ethics and historical view, and it is not dialectics.

So what is dialectic or dialectical logic? Logic which differs from formal logic is called dialectical logic if we think it correct, and sophistry if we think it incorrect. The so-called logical, is able to achieve logical unity, no self-contradiction, in line with a set of established logical rules. Formal logic has a relatively mature set of logical rules. Dialectical logic contains self-contradiction and does not conform to the rules of formal logic, but it is the commonality of many things, which is the relationship we have to admit. Sophistry is also dialectic, but it is incorrect dialectic. Whether dialectics are correct mainly depends on whether they are beneficial to people, whether they are beneficial to the development of science, and whether they can lead to valuable conclusions. Sophistry and stealing concept cannot lead to valuable conclusions.

Philosophy accepts dialectics and science rejects dialectics, which is one of the main differences between science and philosophy. Philosophy accepts reality, science rejects reality, so philosophy is greater than science, and science cannot replace philosophy.

4.2 Blind Negation of Dialectical Logic

Because formal logic is simple and useful but not objective and true, formal logic can't be refused, but it can't be completely credited. Formal logic is the basis of science, science and technology cannot be separated from formal logic. It can be said that formal logic is responsible for most of the achievements of modern civilization. But at the same time, we should not think that formal logic is completely objective and true because of its great merit, and we should not forget that the use of formal logic is conditional. Real and concrete things often do not conform to the law of identity, the law of exclusion of middle, and the law of non-contradiction. The ultimate criterion for testing truth is not logic, but practice. Formal logic is useful but not objective, dialectical logic is objective but not useful. Mr. Wu Zonghuang at Baoding, China, who founded "the theory of subject-object relations", said: "Dialectical logic is fruitless flower." Neither formal logic nor dialectical logic can be abandoned, but many people often go to extremes.

Nowadays, many people believe that real and concrete things must conform to the law of identity, the law of exclusion of middle and the law of non-contradiction. Many scientists regard formal logic as the common law of all things. Some scholars, seeing the use of formal logic, regard these relations as a priori and purely rational, while rejecting dialectics entirely. In a textbook of formal logic, it is clearly stipulated that "Correct thinking should be clear and without contradiction, and the laws of identity, the law of exclusion of middle and the law of non-contradiction embody this requirement. The laws of identity, the law of exclusion of middle, and the law of non-contradiction apply most generally to all concepts, propositions, reasoning, and arguments." They do not know that formal logic is the abstraction of relations in the objective concrete world, and that this abstraction is to a large extent a distortion.