s question
before the appearance of "The Origin of Species". For the individual, he
said, there is an a priori, original, basis (or Anlage) for all mental
life; but in the species all powers have developed in reciprocity with
external conditions. Knowledge is here considered from the practical
point of view, as a weapon in the struggle for life, as an "organon"
which has been continuously in use for generations. In recent years the
economic or pragmatic epistemology, as developed by Avenarius and Mach
in Germany, and by James in America, points in the same direction.
Science, it is said, only maintains those principles and presuppositions
which are necessary to the simplest and clearest orientation in
the world of experience. All assumptions which cannot be applied to
experience and to practical work, will successively be eliminated.

In these views a striking and important application is made of the idea
of struggle for life to the development of human thought. Thought must,
as all other things in the world, struggle for life. But this whole
consideration belongs to psychology, not to the theory of knowledge
(epistemology), which is concerned only with the validity of knowledge,
not with its historical origin. Every hypothesis to explain the
origin of knowledge must submit to cross-examination by the theory of
knowledge, because it works with the fundamental forms and principles
of human thought. We cannot go further back than these forms and
principles, which it is the aim of epistemology to ascertain and for
which no further reason can be given. (The present writer, many years
ago, in his "Psychology" (Copenhagen, 1882; English translation London,
1891), criticised the evolutionistic treatment of the problem of
knowledge from the Kantian point of view.)

But there is another side of the problem which is, perhaps, of more
importance and which epistemology generally overlooks. If new variations
can arise, not only in organic but perhaps also in inorganic nature, new
tasks are placed before the human mind. The question is, then, if it has
forms in which there is room for the new matter? We are here touching
a possibility which the great master of epistemology did not bring to
light. Kant supposed confidently that no other matter of knowledge could
stream forth from the dark source which he called "the thing-in-itself,"
than such as could be synthesised in our existing forms of knowledge.
He mentions the possibility of