It is difficult to draw a sharp line between philosophy and natural
science. The naturalist who introduces a new principle, or demonstrates
a fact which throws a new light on existence, not only renders an
important service to philosophy but is himself a philosopher in the
broader sense of the word. The aim of philosophy in the stricter sense
is to attain points of view from which the fundamental phenomena and
the principles of the special sciences can be seen in their relative
importance and connection. But philosophy in this stricter sense
has always been influenced by philosophy in the broader sense. Greek
philosophy came under the influence of logic and mathematics, modern
philosophy under the influence of natural science. The name of Charles
Darwin stands with those of Galileo, Newton, and Robert Mayer--names
which denote new problems and great alterations in our conception of the
universe.
First of all we must lay stress on Darwin's own personality. His deep
love of truth, his indefatigable inquiry, his wide horizon, and his
steady self-criticism make him a scientific model, even if his results
and theories should eventually come to possess mainly an historical
interest. In the intellectual domain the primary object is to reach
high summits from which wide surveys are possible, to reach them toiling
honestly upwards by way of experience, and then not to turn dizzy when
a summit is gained. Darwinians have sometimes turned dizzy, but Darwin
never. He saw from the first the great importance of his hypothesis, not
only because of its solution of the old problem as to the value of the
concept of species, not only because of the grand picture of natural
evolution which it unrolls, but also because of the life and inspiration
its method would impart to the study of comparative anatomy, of instinct
and of heredity, and finally because of the influence it would exert on
the whole conception of existence. He wrote in his note-book in the
year 1837: "My theory would give zest to recent and fossil comparative
anatomy; it would lead to the study of instinct, heredity, and
mind-heredity, whole (of) metaphysics." ("Life and Letters of Charles
Darwin", Vol. I. page 8.)
We can distinguish four main points in which Darwin's investigations
possess philosophical importance.
The evolution hypothesis is much older than Darwin; it is, indeed, one
of the oldest guessings of human thought. In the eighteenth century it
was put forward by Diderot and Lamettrie and suggested by Kant (1786).
As we shall see later, it was held also by several philosophers in the
first half of the nineteenth century. In his preface to "The Origin of
Species", Darwin mentions the naturalists who were his forerunners.
But he has set forth the hypothesis of evolution in so energetic
and thorough a manner that it perforce attracts the attention of
all thoughtful men in a much higher degree than it did before the
publication of the "Origin".
And further, the importance of his teaching rests on the fact that he,
much more than his predecessors, even than Lamarck, sought a foundation
for his hypothesis in definite facts. Modern science began by
demanding--with Kepler and Newton--evidence of verae causae; this
demand Darwin industriously set himself to satisfy--hence the wealth of
material which he collected by his observations and his experiments.
He not only revived an old hypothesis, but he saw the necessity of
verifying it by facts. Whether the special cause on which he founded the
explanation of the origin of species--Natural Selection--is sufficient,
is now a subject of discussion. He himself had some doubt in regard
to this question, and the criticisms which are directed against his
hypothesis hit Darwinism rather than Darwin. In his indefatigable search
for empirical evidence he is a model even for his antagonists: he has
compelled them to approach the problems of life along other lines than
those which were formerly followed.
Whether the special cause to which Darwin appealed is sufficient or not,
at least to it is probably due the greater part of the influence which
he has exerted on the general trend of thought. "Struggle for existence"
and "natural selection" are principles which have been applied, more or
less, in every department of thought. Recent research, it is true, has
discovered greater empirical discontinuity--leaps, "mutations"--whereas
Darwin believed in the importance of small variations slowly
accumulated. It has also been shown by the experimental method, which
in recent biological work has succeeded Darwin's more historical method,
that types once constituted possess great permanence, the fluctuations
being restricted within clearly defined boundaries. The problem has
become more precise, both as to variation and as to heredity. The inner
conditions of life have in both respects shown a greater independence
than Darwin had supposed in his theory, though he always admitted that
the cause of variation was to him a great enigma, "a most perplexing
problem," and that the struggle for life could only occur where
variation existed. But, at any rate, it was of the greatest importance
that Darwin gave a living impression of the struggle for life which is
everywhere going on, and to which even the highest forms of existence
must be amenable. The philosophical importance of these ideas does not
stand or fall with the answer to the question, whether natural selection
is a sufficient explanation of the origin of species or not: it has
an independent, positive value for everyone who will observe life and
reality with an unbiassed mind.
In accentuating the struggle for life Darwin stands as a
characteristically English thinker: he continues a train of ideas which
Hobbes and Malthus had already begun. Moreover in his critical views as
to the conception of species he had English forerunners; in the middle
ages Occam and Duns Scotus, in the eighteenth century Berkeley and Hume.
In his moral philosophy, as we shall see later, he is an adherent of the
school which is represented by Hutcheson, Hume and Adam Smith. Because
he is no philosopher in the stricter sense of the term, it is of great
interest to see that his attitude of mind is that of the great thinkers
of his nation.
In considering Darwin's influence on philosophy we will begin with an
examination of the attitude of philosophy to the conception of evolution
at the time when "The Origin of Species" appeared. We will then examine
the effects which the theory of evolution, and especially the idea
of the struggle for life, has had, and naturally must have, on the
discussion of philosophical problems.