History of Western Philosophy - Bertrand Russell [413]
The romantic form of revolt is very different from the rationalist form, though both are derived from the French Revolution and the philosophers who immediately preceded it. The romantic form is to be seen in Byron in an unphilosophical dress, but in Schopenhauer and Nietzsche it has learnt the language of philosophy. It tends to emphasize the will at the expense of the intellect, to be impatient of 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 each generation. Thus from age to age deer run more swiftly, cats stalk their prey more silently, and giraffes' necks become longer. Given enough time, this mechanism, so Darwin contended, could account for the whole long development from the protozoa to homo sapiens.
This part of Darwin's theory has been much disputed, and is regarded by most biologists as subject to many important qualifications. That, however, is not what most concerns the historian of nineteenth-century ideas. From the historical point of view, what is interesting is Darwin's extension to the whole of life of the economics that characterized the philosophical radicals. The motive force of evolution, according to him, is a kind of biological economics in a world of free competition. It was Malthus's doctrine of population, extended to the world of animals and plants, that suggested to Darwin the struggle