Here the demand to take account of the objective dialectic in studying the subjective dialectic, i.e., dialectical thinking in some science, is clearly expressed. Of course, by no means does this imply that we close our eyes to the subjective conditions of this thinking. The same Engels who established a correspondence between being and thinking in mathematics says that “all laws of number are dependent upon and determined by the system that is used. In the binary and ternary system 2 x 2 does not = 4, but = 100 or = 11” [ibid., p. 523]. Extending this, we might say that subjective assumptions which follow from knowledge will always influence the way of expressing the laws of nature and the relation between the different concepts. We must take them into account, but always as a reflection of the objective dialectic.

We must, therefore, contrast epistemological critique and formal logic as the foundations of a general science with a dialectic “which is conceived of as the science of the most general laws of all movement. This implies that its laws must be valid for both movement in nature and human history and movement in thinking” [ibid., p. 530]. This means that the dialectic of psychology—this is what we may now call the general psychology in opposition to Binswanger’s definition of a “critique of psychology”—is the science of the most general forms of movement (in the form of behavior and knowledge of this movement), i.e., the dialectic of psychology is at the same time the dialectic of man as the object of psychology, just as the dialectic of the natural sciences is at the same time the dialectic of nature.

Engels does not even consider the purely logical classification of judgments in Hegel to be based merely on thinking, but on the laws of nature. This he regards as a distinguishing characteristic of dialectical logic.

What in Hegel seems a development of the judgment as a category of thinking as such, now appears to be a development of our knowledge of the nature of movement based on empirical grounds. And this proves that the laws of thinking and the laws of nature correspond necessarily with each other as soon as they are known properly [ibid., p.

493].

The key to general psychology as a part of dialectics lies in these words: this correspondence between thinking and being in science is at the same time object, highest criterion, and even method, i.e., general principle of the general psychology.