Köhlcr (1917) demonstrated in practice how we may prove the presence of thinking in apes without any introspection and even study the course and structure of this process through the method of the interpretation of objective reactions. Korniov (1922) demonstrated how we may measure the energetic budget of different thought operations using the indirect method: the dynamoscope is used by him as a thermometer. Wundt’s mistake resided in the mechanical application of equipment and the mathematical method to check and correct. He did not use them to extend introspection, to liberate himself from it, but to tie himself to it. In most of Wundt’s investigations introspection was essentially superfluous. It was only necessary to single out the unsuccessful experiments. In principle it is totally unnecessary in Kornilov’s theory. But psychology must still create its thermometer. Korniov’s research indicates the path.

We may summarize the conclusions from our investigation of the narrow sensualist dogma by again referring to Engels’ words about the activity of the eye which in combination with thinking helps us to discover that ants see what is in- visible to us.

Psychology has too long striven for experience instead of knowledge. In the present example it preferred to share with the ants their visual experience of the sensation of chemical beams rather than to understand their vision scientifically.

As to the methodological spine that is supporting them there are two scientific systems. Methodology is always like the backbone, the skeleton in the animal’s organism. Very primitive animals, like the snail and the tortoise, carry their skeleton on the outside and they can, like an oyster, be separated from their skeleton. What is left is a poorly differentiated fleshy part. Higher animals carry their skeleton inside and make it into the internal support, the bone of each of their movements. In psychology as well we must distinguish lower and higher types of methodological organization.

This is the best refutation of the sham empiism of the natural sciences. It turns out that nothing can be transposed from one theory to another. It would seem that a fact is always a fact. Despite the different points of departure and the different aims one and the same object (a child) and one and the same method (objective observation) should make it possible to transpose the facts of psychology to reflexology. The difference would only be in the interpretation of the same facts. In the end the systems of Ptolemy27 and Copernicus~ rested upon the same facts as well. [But] It turns out that facts obtained by means of different principles of knowledge are different facts.

Thus, the debate about the application of the biogenetic principle in psychology is not a debate about facts. The facts are indisputable and there are two groups of them: the recapitulation of the stages the organism goes through in the development of its structure as established by natural science and the indisputable traits of similarity between the phylo- and ontogenesis of the mind. It is particularly important that neither is there any debate about the latter group. Koffka [1925, pp. 32], who contests this theory and subjects it to a methodological analysis, resolutely declares that the analogies, from which this false theory proceeds, exist beyond any doubt. The debate concerns the meaning of these analogies and it turns out that it cannot be decided without analyzing the principles of child psychology, without having a general idea of childhood, a conception of the meaning and the biological sense of childhood, a certain theory of child development. It is quite easy to find analogies. The question is how to search for them. Similar analogies may be found in the behavior of adults as well.

‘iWo typical mistakes are possible here: one is made by Hall.29 Thorndike and Groos have brilliantly exposed it in critical analyses. The latter [Groos, 1904/1921,