The continual transitions that occur, forbid our speaking of the "individual," etc.; the "number" of beings itself fluctuates. We should know nothing of time or of movement, if, in a rough way, we did not believe we saw things "standing still" behind or in front of things moving. We should also know just as little about cause and effect, and without the erroneous idea of "empty space" we should never have arrived at the concept of space at all. The principle of identity is based on the "fact of appearance" that there are some things alike. Strictly speaking, it would not be possible to "understand" and "know" an evolving world; something which is called "knowledge" exists only in so far as the "understanding" and "knowing" intellect already finds an adjusted and rough world to hand, fashioned out of a host of mere appearances, but become fixed to the extent in which this kind of appearance has helped to preserve life; only to this extent is "knowledge" possible—that is to say, as a measuring of earlier and more recent errors by one another.
521.
Concerning logical appearance.—The concept "individual" and the concept "species" are equally false and only apparent. "Species" only expresses the fact that an abundance of similar creatures come forth at the same time, and that the speed of their further growth and of their further transformation has been made almost imperceptible for a long time: so that the actual and trivial changes and increase of growth are of no account at all (—a stage of evolution in which the process of evolving is not visible, so that, not only does a state of equilibrium seem to have been reached, but the road is also made clear for the error of supposing that an actual goal has been reached—and that evolution had a goal...).
The form seems to be something enduring, and therefore valuable; but the form was invented merely by ourselves; and however often "the same form is attained," it does not signify that it is the same form,—because something new always appears; and we alone, who compare, reckon the new with the old, in so far as it resembles the latter, and embody the two in the unity of "form." As if a type had to be reached and were actually intended by the formative processes.
Form, species, law, idea, purpose—the same fault is made in respect of all these concepts, namely, that of giving a false realism to a piece of fiction: as if all phenomena were infused with some sort of obedient spirit—an artificial distinction is here made between that which acts and that which guides action (but both these things are only fixed in order to agree with our metaphysico-logical dogma: they are not "facts").
We should not interpret this constraint in ourselves, to imagine concepts, species, forms, purposes, and laws ("a world of identical cases") as if we were in a position to construct a real world; but as a constraint to adjust a world by means of which our existence will be ensured: we thereby create a world which is determinable, simplified, comprehensible, etc., for us.
The very same constraint is active in the functions of the senses which support the reason—by means of simplification, coarsening, accentuation, and interpretation; whereon all "recognition," all the ability of making one's self intelligible rests. Our needs have made our senses so precise, that the "same world of appearance" always returns, and has thus acquired the semblance of reality.
Our subjective constraint to have faith in logic, is expressive only of the fact that long before logic itself became conscious in us, we did nothing save introduce its postulates into the nature of things: now we find ourselves in their presence,—we can no longer help it,—and now we would fain believe that this constraint is a guarantee of "truth." We it was who created the "thing," the "same thing," the subject, the attribute, the action, the object, the substance, and the form, after we had carried the process of equalising, coarsening, and simplifying as far as possible. The world seems logical to us, because we have already made it logical.
522.
Fundamental solution.—We believe in reason: this is, however, the philosophy of colourless concepts. Language is built upon the most naïf prejudices.