It is perhaps easier to realize this in the case of a
science than of philosophy, since each of the sciences
is less wide in its scope, and consequently better
organized; but there is no real difference between
science and philosophy in this respect. We can doubt-
less observe what are no more than changing popular
fashions in philosophical opinions, as in science or
art, but such mere fashions do not concern us. Nor
are we much concerned with books of a philosophical
character which ignore previous philosophical de-
velopment, and are thus in reality out of date.

Philosophical ideas are essentially bound up with
ideas applied in all branches of knowledge. Progress
in philosophy implies progress in these branches, and
vice versa. This follows from the fact that the experi-
ence of which philosophy endeavours to give a co-
herent account is presented in special forms which
different branches of science confer upon it. These
different forms furnish philosophy with its material,
and the need for philosophy arises from the fact that
the presentations as they initially stand are found not
to be consistent with one another. Apart from the
sciences there would be no philosophy. The task of
philosophy is to bring the separate presentations into
consistency with one another, and this necessarily
influences them all, in at any rate some degree. Physi-
cal science, for instance, presents us with one form of
knowledge, whereas the study of human behaviour
in ordinary life and in history presents us with another
very different and apparently contradictory form.

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