or one moment in our choice.
But, of course, if the evidence is supposed _not_ to be equal and
parallel--_i.e._, if it is supposed that the theory of natural relation
is not so competent a theory to explain the facts of adaptation as is
that of intelligent design--then the objection is no longer the one that
we are considering. It is quite another objection, and one which is not
_prima facie_ absurd; it requires to be met by examining how far the
theory of natural selection _is_ able to explain the facts. Let us state
the problem clearly.

Innumerable cases of adaptation of organisms to their environment are
the observed facts for which an explanation is required. To supply this
explanation two, and only two, hypotheses are in the field. Of these
two hypotheses one is, intelligent design manifested in creation; and
the other is, natural selection manifested during the countless ages of
the past. Now it would be proof positive of intelligent design if it
could be shown that all species of plants and animals were
_created_--that is _suddenly_ introduced into the complex conditions of
their life; for it is quite inconceivable that any cause other than
intelligence could be competent to adapt an organism to its environment
_suddenly_. On the other hand, it would be proof presumptive of natural
selection if it could be shown that one species becomes slowly
transmuted into another--_i.e._, that one set of adaptations may be
gradually transformed into another set of adaptations according as
changing circumstances require. This would be proof presumptive of
natural selection, because it would then become amply probable that
natural selection might have brought about many, or most, of the cases
of adaptations which we see; and if so, the law of parsimony excludes
the rival hypothesis of intelligent design. Thus the whole question as
between natural selection and supernatural design resolves itself into
this--Were all the species of plants and animals separately created, or
were they slowly evolved? For if they were specially created, the
evidence of supernatural design remains unrefuted and irrefutable;
whereas if they were slowly evolved, that evidence has been utterly and
for ever destroyed. The doctrine of natural selection therefore depends
for its validity on the doctrine of organic evolution; for if once the
fact of organic evolution were established, no one would dispute that
much of the adaptation was probably effected b