ptation were proved to be fully explicable by the theory of
descent, this would constitute no disproof of the theory of design: all
the cases of adaptation, it is argued, might still be due to design,
even though they admit of being hypothetically accounted for by the
theory of descent. I have heard an eminent Professor tell his class that
the many instances of mechanical adaptation discovered and described by
Darwin as occurring in orchids, seemed to him to furnish better proof of
supernatural contrivance than of natural causes; and another eminent
Professor has informed me that, although he had read the _Origin of
Species_ with care, he could see in it no evidence of natural selection
which might not equally well have been adduced in favour of intelligent
design. But here we meet with a radical misconception of the whole
logical attitude of science. For, be it observed, this exception _in
limine_ to the evidence which we are about to consider does not question
that natural selection _may_ be able to do all that Darwin ascribes to
it. The objection is urged against his interpretation of the facts
merely on the ground that these facts might _equally well_ be ascribed
to intelligent design. And so undoubtedly they might, if we were all
simple enough to adopt a supernatural explanation whenever a natural one
is found sufficient to account for the facts. Once admit the irrational
principle that we may assume the operation of higher causes where the
operation of lower ones is sufficient to explain the observed phenomena,
and all our science and all our philosophy are scattered to the winds.
For the law of logic which Sir William Hamilton called the law of
parsimony--or the law which forbids us to assume the operation of higher
causes when lower ones are found sufficient to explain the observed
effects--this law constitutes the only barrier between science and
superstition. It is always possible to give a hypothetical explanation
of any phenomenon whatsoever, by referring it immediately to the
intelligence of some supernatural agent; so that the only difference
between the logic of science and the logic of superstition consists in
science recognising a validity in the law of parsimony which
superstition disregards. Therefore one can have no hesitation in saying
that this way of looking at the evidence in favour of natural selection
is not a scientific or a reasonable way of looking at it, but a purely
superstitious way. Let us