What has been carried to the rigor of a chemical rule here exists as a general principle in the whole area of scientific language.

Lange (1914, p. 96) says that

Parallelism is a word which seems innocent at first sight. It conceals, however, a terrible idea—the idea of the secondary and accidental nature of technique in the world of physical phenomena.

This innocent word has an instructive history. Introduced by Leibniz it was applied to the solution of the psychophysical problem which goes back to Spinoza, changing its name many times in the process. Høffding [1908, p. 91, footnote 1] calls it the identity hypothesis and considers that it is the

only precise and opportune name . . .. The frequently used term ‘monism’ is etymologically correct but inconvenient, because it has often been used.. .by a more vague and inconsistent conception. Names such as ‘parallelism’ and ‘dualism’ are inadequate, because they. . .smuggle in the idea that we must conceive of the mental and the bodily as two completely separate series of developments (almost as a pair of rails) which is exactly what the hypothesis does not assume.

It is Wolff’s35 hypothesis which must be called dualistic, not Spinoza’s.

Thus, a single hypothesis is now called (1) monism, now (2) dualism, now (3) parallelism, and now (4) identity. We may add that the circle of Marxists who have revived this hypothesis (as will be shown below)—Plekhanov, and after him Sarab’janov,36 Frankfurt and others—view it precisely as a theory of the unity, but not identity of the mental and the physical. How could this happen? Obviously, the hypothesis itself can be developed on the basis of different more general views and may acquire different meanings depending on them: some emphasize its dualism, others its monism etc. Haffding [1908, p. 96] remarks that it does not exclude a deeper metaphysical hypothesis, in particular idealism. In order to become a philosophical world view, hypotheses must be elaborated anew and this new elaboration resides in the emphasis on now this and now that aspect. Very important is Lange’s (1914, p. 76) reference:

We find psychophysical parallelism in the representatives of the most diverse philosophical currents—the dualists (the followers of Descartes37), the monists (Spinoza), Leibnitz çmetaphysical idealism), the positivists-agnostics (Bain, Spencer38), Wundt and Paulsen 9(voluntaristic metaphysics).

Høffding [1908, p. 117] says that the unconscious follows from the hypothesis of identity:

In this case we act like the philologist who via conjectural critique [Konjekturalkritilc] supplements a fragment of an ancient writer. Compared to the physical world the mental world is for us a fragment; only by means of a hypothesis can we supplement

it.

This conclusion follows inevitably from [his] parallelism.

That is why Chelpanov is not all that wrong when he says that before 1922 he called this theory parallelism and after 1922 materialism. He would be entirely right if his philosophy had not been adapted to the season in a slightly mechanical fashion. The same goes for the word “function” (I mean function in the mathematical sense). The formula “consciousness is a function of the brain” points to the theory of parallelism; “physiological sense” leads to materialism. When Kornilov (1925) introduced the concept and the term of a functional relation between the mind and the body, he regarded parallelism as a dualistic hypothesis, but despite this fact and without noticing it himself, he introduced this theory, for although he rejected the concept of function in the physiological sense, its second sense remained.