The so-called truth is that the subjective conforms to the objective understanding. To judge whether subjectivity conforms to objectivity, we must compare subjectivity with objectivity, that is to say, as the standard of truth, we must have the characteristics of combining subjectivity with objectivity.
(2) It is impossible to find the standard of truth within the scope of people's subjective understanding. We can't use subjectivity to test subjectivity, nor can we use cognition to test knowledge. The objective thing itself cannot be the criterion for testing truth, because the objective thing cannot be compared with the subjective knowledge itself.
(3) Practice is what the spirit sees in the material and what the subjective sees in the objective. In addition to universality, practice has the advantage of direct reality. The so-called "direct reality" means that practice can turn correct understanding into direct reality. In this way, practice becomes a bridge between subjective and objective relations.
In this way, in practice, people can transform the world under the guidance of a certain understanding, and directly lead to realistic results. If people achieve the expected purpose, it proves that this understanding conforms to the regularity of objective things and is correct; On the other hand, it is not correct.
The certainty and uncertainty of practical standards
Practice, as a criterion for testing truth, is both absolute and relative, both definite and uncertain.
(1) The absoluteness and certainty of the practice standard are as follows:
First, practice is the only objective criterion for testing truth.
Second, people's understanding should be tested by practice in the final analysis. In the long run, practice can test all knowledge. All correct understandings will eventually be affirmed by practice, and all wrong understandings will eventually be overthrown by practice.
(2) The relativity and uncertainty of practical standards are as follows:
First, it is a process of testing knowledge with practice. The practice in each historical stage cannot completely confirm or refute all the theories put forward by the times. At the same time, a certain correct understanding that has been confirmed by practice will continue to be tested by practice.
Second, practice is concrete and historical, and the correctness of a certain understanding confirmed by practice is relative and limited.
(3) Adhering to the unity of absoluteness and relativity of practical standards and the unity of certainty and uncertainty is the dialectics of adhering to the standard of truth. Only seeing the relativity of practical standards and denying their absoluteness will lead to relativism, subjective idealism and agnosticism.