does not.
Secondly, is the principle of form self-explanatory? Here,
again, we must answer negatively. Most of what was said
of Plato under this head applies equally to Aristotle. Plato
asserted that the Absolute is reason, and it was therefore
incumbent on him to show that his account of reason was
truly rational. He failed to do so. Aristotle asserts the
same thing, for form is only {336} another word for rea-
son. Hence he must show us that this form is a rational
principle, and this means that he must show us that it is
necessary. But he fails to do so. How is form a necessary
and self-determining principle? Why should there be such
a principle as form? We cannot see any necessity. It is
a mere fact. It is nothing but an ultimate mystery. It is
so, and that is an end of it. But why it should be so, we
cannot see. Nor can we see why there should be any of the
particular kinds of form that there are. To explain this,
Aristotle ought to have shown that the forms constitute a
systematic unity, that they can be deduced one from an-
other, just as we saw that Plato ought to have deduced all
the Ideas from one another. Thus Aristotle asserts that the
form of plants is nutrition, of animals sensation, and that
the one passes into the other. But even if this assertion be
true, it is a mere fact. He ought not merely to have as-
serted this, but to have deduced sensation from nutrition.
Instead of being content to allege that, as a fact, nutrition
passes into sensation, he ought to have shown that it must
pass into sensation, that the passage from one to the other
is a logical necessity. Otherwise, we cannot see the reason
why this change occurs. That is to say, the change is not
explained.Consider the effects of this omission upon the theory of evo-
lution. We are told that the world-process moves towards
an end, and that this end is the self-realization of reason,
and that it is proximately attained in man, because man
is a reasoning being. So far this is quite intelligible. But
this implies that each step in evolution is higher than the
last because it approaches nearer to {337} the end of the
world-process. And as that end is the realization of rea-
son, this is equivalent to saying that each step is higher
than the last because it is more rational. But how is sen-
sation more rational than nutrition? Why should it not
be the other way about? Nutrition passes through sensa-
tion into human reason. But why should not sensation pass
through nutrition into human reason? Why should not the
order be reversed? We cannot explain. And such an ad-
mission is absolutely fatal to any philosophy of evolution.
The whole object of such a philosophy is to make it clear
to us why the higher form is higher, and why the lower is
lower: why, for example, nutrition must, as lower, come
first, and sensation second, and notvice versa. If we can
see no reason why the order should not be reversed, this
simply means that our philosophy of evolution has failed
in its main point. It means that we cannot see any real
difference between lower and higher, and that therefore we
have merely change without development, since it is indif-
ferent whether A passes into B, or B into A. The only way
in which Aristotle could have surmounted these difficulties
would have been to prove that sensation is a development
of reason which goes beyond nutrition. And he could only