chains of reasoning, and to glorify violence of certain kinds. In practical politics it is important as
an ally of nationalism. In tendency, if not always in fact, it is definitely hostile to what is
commonly called reason, and tends to be anti-scientific. Some of its most extreme forms are to be
found among Russian anarchists, but in Russia it was the rationalist form of revolt that finally
prevailed. It was Germany, always more susceptible to romanticism than any other country, that
provided a governmental outlet for the anti-rational philosophy of naked will.
So far, the philosophies that we have been considering have had an inspiration which was
traditional, literary, or political. But there were two other sources of philosophical opinion,
namely science and machine production. The second of these began its theoretical influence with
Marx, and has grown gradually more important ever since. The first has been important since the
seventeenth century, but took new forms during the nineteenth century.
What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth.
Darwin's theory had two parts. On the one hand, there was the doctrine of evolution, which
maintained that the different forms of life had developed gradually from a common ancestry. This
doctrine, which is now generally accepted, was not new. It had been maintained by Lamarck and
by Darwin's grandfather Erasmus, not to mention Anaximander. Darwin supplied an immense
mass of evidence for the doctrine, and in the second part of his theory believed himself to have
discovered the cause of evolution. He thus gave to the doctrine a popularity and a scientific force
which it had not previously possessed, but he by no means originated it.
The second part of Darwin's theory was the struggle for existence and the survival of the fittest.
All animals and plants multiply faster than nature can provide for them; therefore in each
generation many perish before the age for reproducing themselves. What determines which will
survive? To some extent, no doubt, sheer luck, but there is another cause of more importance.
Animals and plants are, as a rule, not exactly like their parents, but differ slightly by excess or
defect in every measurable characteristic. In a given environment, members of the same species
compete for survival, and those best adapted to the environment have the best chance. Therefore
among chance variations those that are favourable will preponderate among adults in