y valid in themselves, but also by
far the most formidable objections which the theory of natural selection
has encountered. From another point of view, however, I am equally
convinced that they all admit of absolute annihilation. This strong
antithesis arises, as I have said, from differences of standpoint, or
from differences in the view which we take of the theory of natural
selection itself. If we understand this theory to set forth natural
selection as the sole cause of organic evolution, then all the above
objections to the theory are not merely, as already stated, valid and
formidable, but as I will now add, logically insurmountable. On the
other hand, if we take theory to consist merely in setting forth natural
selection as a factor of organic evolution, even although we believe it
to have been the chief factor or principal cause, all the three
objections in question necessarily vanish. For in this case, even if it
be satisfactorily proved that the theory of natural selection is unable
to explain the three classes of facts above mentioned, the theory is not
thereby affected: facts of each and all of these classes may be
consistently left by the theory to be explained by causes other than
natural selection--whether these be so far capable or incapable of
hypothetical formulation. Thus it is evident that whether the three
objections above named are to be regarded as logically insurmountable by
the theory, or as logically non-existent in respect to it, depends
simply upon the manner in which the theory itself is stated.

In the next volume a great deal more will have to be said upon these
matters--especially with regard to the causes other than natural
selection which in my opinion are capable of explaining these so-called
"difficulties." In the present connexion, however, all I have attempted
to show is, that, whatever may be thought touching the supplementary
theories whereby I shall endeavour to explain the facts of inutility,
cross-sterility, and non-occurrence of free intercrossing, no one of
these facts is entitled to rank as an objection against the theory of
natural selection, unless we understand this theory to claim an
exclusive prerogative in the field of organic evolution. This, as we
have previously seen, is what Mr. Wallace does claim for it; while on
the other hand, Mr. Darwin expressly--and even vehemently--repudiates
the claim: from which it follows that all the three main objections
against the th