The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality | Page 8

the hypothesis of an evolution rendered necessary the
attempt at explaining this evolution, and showed Darwin's method of
explaining it by his selection theory. It will be well for the reader to
keep distinctly in mind the difference between these problems and
theories, in following our investigations, even if we cannot arrange our
historical sketch according to the natural principle of division arising
from these differences.
For it lies in the nature of the question itself, that {28} these theories, in

their historical progress, did not appear singly, but together. Those who
inclined to the theory of a descent of species could claim for it the
attention of scientific investigators only after having also made the
attempt at conceiving this descent in a concrete way, and according to
certain analogies of observation. The only analogy of the kind appeared
in the sphere of individual development and individual differences on
the one hand, and in that of closely related characters of allied species
on the other; and thus led of itself to the evolution theory. As soon as
the naturalists thought they had found the causes of such an evolution
of the species, they naturally placed these causes in the foreground of
their demonstrations, and erected upon them the structure of their entire
theory; thus treating descent, evolution and selection as one single and
indissolubly connected theory. But this manner of treating the question
had also its dangers, which have already caused a great deal of
confusion and misunderstanding, as well as much unprofitable
controversy. Often friends and enemies of the theories placed that
which was in favor of the theory of descent to the credit of the
evolution or selection theory; and, on the other hand, that which
seemed opposed to the selection theory was often held to be a
weakening of the evolution and descent theory; and this was done, not
only by amateurs, but often enough by the highest authorities also. In
reality, however, it is quite conceivable that the idea of a descent may
prove correct, and possibly the idea of an evolution of the species will
have to be replaced by that of a heterogenetic generation, or by the
theory that certain groups in the organic system are originated {29} by
heterogenetic generation, and others by evolution; and so the evolution
theory must share with the theory of heterogenetic generation, or of a
metamorphosis of germs. On the other hand, it is conceivable that even
where the evolution theory is confirmed, the evolution can be
accounted for wholly or partly by other reasons than those derived from
the selection theory. And even this result of present investigations is
not inconceivable: that the reasons for and against the different theories
will be found to balance one another to such a degree that they will
sooner or later lead science, in answering the question of the origin of
species, to the old confession of Socrates--"Ignoramus."
We shall, therefore, have to arrange our historical sketch according to

the historical order of the appearance of the theories, and treat the
problems more or less as an undivided whole. But we shall keep in
mind, during our historical sketch, not only the logical separation of the
problems in question, in order not to lose clearness of judgment, but we
shall also at the end of our review, if we consider the present condition
of the problems, have to examine the same once more in detail, so far
as regards the above mentioned separation.
* * * * *
{30}
CHAPTER I.
RISE OF THE DARWINIAN THEORIES.
§ 1. Direct Predecessors.--Lamarck.
The first man who gave direct expression to the idea of a successive
generation of the species through transmutation, and who attempted to
follow it up in a scientific way, was the French naturalist and
philosopher, Jean Lamarck, born 1744. In the year 1801, and
subsequently, he published his views, first in smaller essays and
afterward more in detail in his "Philosophie Zoologique," which
appeared in 1809, and in the first volume of his "Histoire Naturelle des
Animaux sans Vertèbres," published in 1815. In these works Lamarck
upholds fully the descent and evolution theory, and maintains that the
simplest organisms are generated through a generatio spontanea, which
is still taking place; but that all the more developed organisms,
including man, are descended through a gradual change from other
species. With this theory, he put himself in direct and conscious
opposition to the old doctrine of the immutability of species and their
characteristics, which had been ably maintained by Linnæus, and also
made some attempts at explanation which approach very nearly the
selection theory. A change in the physical conditions of life, especially
the force of habit in the use or disuse of the organs, the inheritance of
physical and psychical {31} qualities thus