Commentary on the Philosophy of Nature, Chapter 41
What Separates Erdmann from the Other Two
And at one point he stands closer to what is decisive than he himself was aware. In 1858 he has the history of the earth together, the fossil sequence, the increasing complexity, embryonic development, and the common cellular ground of plant and animal — and he assembles all of it into a series of separate productions instead of a family tree. The thought that would have ordered his own findings, common descent with variation, he does not take. A year later it stands with Darwin. [KF]
Erdmann’s earth is an old one at that: its “generative activity” has “as good as ceased,” and the species remain unchanged. That is the narrowest version of natural history among the three — and it is the reason why the other two are to be held beside it. The one opened it further before him, the other closed it again after him.
And with this the three can be set side by side. All retain the method and change the content; they differ in how far they let experience have its say — and the difference does not run parallel to time. Rosenkranz has the most open natural history, Erdmann the clearest categorial outline, Michelet the most extensive material with the least self-limitation.
Erdmann retains Hegel’s structure and gives it a ground that Hegel never provides: the sequence of stages is a series of ever less unsuccessful attempts to resolve the contradiction that nature is reason without being rational. That is the clearest categorial outline to come out of the school — and it stands on twenty pages in a book about academic study.
On the question of evolution, this produces a movement that looks almost dialectical: Rosenkranz opens the system in 1850 to an unknown future of nature. Erdmann closes this future again in 1858 through the constancy of species. Michelet knows Darwin in 1876, opens the species — and closes the types instead. None of the three arrives at the thought that would have ordered all their findings differently. [KF]
What distinguishes him in this is his reticence: The two lines — the plummet line and the radius — “can never cross […] rather, in time they will meet.” Whoever takes this seriously cannot overrule empirical evidence but can only wait for it. [KF]