The Essence of Darwinism and the Basis of Modern Orthodoxy 147
The premises of Darwin's theory (the branches and sub-branches of the coral
model) are organically connected. One might be able to excise a single branch
without killing the others, but some pain and readjustment will certainly be felt
throughout the entire structure. The three sub-branches of the "creativity" limb, for
example, are strongly conjoined in this manner. If variation forms an isotropic
sphere (the expectation of sub-branch one), then change by natural selection can
only occur a short step at a time (as predicted by the gradualism of sub-branch
two). And if variation imposes no constraint upon the direction of change (an
inference from isotropy), then natural selection works freely and adaptation
prevails (as required by sub-branch three).
Finally, as so often emphasized throughout this book, we must recognize and
embrace natural history as a science of relative frequencies. None of these basic
Darwinian premises operates without exception throughout nature. Darwin
insisted—explicitly and vociferously—that natural selection only enjoyed a
predominant relative frequency, not exclusivity: "the main but not exclusive means
of modification," as he writes at the close of the introduction (p. 6). Darwin then
extended his claim for a predominant relative frequency, but not for exclusivity, to
all other sub-branches of his essential argument as well. Failure of raw material
might occasionally explain a puzzling absence of evolutionary modification—but
lack of selective pressure for change surely represents the more likely explanation
for stasis by far. Substantial change might occur as a very rare event, but most
alteration must be insensible, even on geological scales: "We see nothing of these
slow changes in progress, until the hand of time has marked the long lapse of ages"
(p. 84).
Understanding Darwin's mode of justification by relative frequency be-
Charles Darwin surely ranks as the most genial of history's geniuses—possessing none of
those bristling quirks and arrogances that usually mark the type. Yet, one subject invariably
aroused his closest approach to fury—the straw-man claim, so often advanced by his adversaries,
that he regarded natural selection as an exclusive mode of change in evolution. Darwin, who
understood so well that natural history works by relative frequency, explicitly denied exclusivity
and argued only for dominance. So frustrated did he become at the almost willful
misunderstanding of a point so clearly made, that he added this rueful line to the 6th edition of
the Origin (1872b, p. 395): "As my conclusions have lately been much misrepresented, and it has
been stated that I attribute the modification of species exclusively to natural selection, I may be
permitted to remark that in the first edition of this work, and subsequently, I placed in a most
conspicuous position—namely at the close of the Introduction—the following words: 'I am
convinced that natural selection has been the main, but not the exclusive means of modification.'
This has been of no avail. Great is the power of steady misinterpretation."
Darwin's good friend G. J. Romanes, author of a famous essay on Darwin's pluralism vs.
the panselectionism of Wallace and Weismann, wrote of this statement (1900, p. 5): "In the
whole range of Darwin's writings there cannot be found a passage so strongly worded as this: it
presents the only note of bitterness in all the thousands of pages which he has published." But
Darwin wrote other bristling statements on the same sensitive subject. In 1880, for example, he
castigated Sir Wyville Thomson for caricaturing him as a panselectionist: "This is a standard of
criticism not uncommonly reached by theologians and metaphysicians when they write on
scientific subjects, but is something new as coming from a naturalist ... Can Sir Wyville
Thomson name any one who has said that the evolution of species depends only on natural
selection?" (1880b, p. 32).