166 THE STRUCTURE OF EVOLUTIONARY THEORY
has become taboo in our profession. I will then use this characterization as a
foundation for classifying various challenges and controversies—just as Kellogg
did—according to their stance towards the essential concepts of Darwinism. The
most interesting and far-reaching challenges directly engage these essential
concepts, either as alternatives to refute them in part, or as auxiliaries to expand
and reinterpret them in fundamental ways. This book presents, as its primary
thesis, the notion that (i) Darwinism may be viewed as a platform with a tripod of
essential support; (ii) each leg of the tripod now faces a serious reforming critique
acting more as an auxiliary than an alternative formulation; and (Hi) the three
critiques hold strong elements in common, and may lead to a fundamentally
revised evolutionary theory with a retained Darwinian core.
We must rank challenges by their degree of engagement with the Darwinian
core; we cannot follow a strategy of mindless "raw empiricism" towards the Origin
and simply compile a list of Darwin's mistakes. All great works are bursting with
error; how else could true creativity be achieved? Could anyone possibly
reformulate a universe of thought and get every detail right the first time? We
should not simply count Darwin's errors, but rather assess their importance relative
to his essential postulates. (Consider, for example, the standard rhetorical, and
deeply anti-intellectual, ploy of politically motivated and destructive critics,
American creationists in particular. They just list the mistakes, envelop each in a
cloud of verbal mockery, and pretend that the whole system has drowned in this
tiny puddle of inconsequential error.)
I suggest that we use the list of minimal commitments to gauge the status of
Darwin's errors. Very few faults of simple fact can, as individual items, be of much
consequence unless they confute a core commitment. Darwin argued, for example,
that swimbladders evolved into lungs (see p. 107) though exactly the opposite
occurred—but no premise of the general theory suffers any injury by this mistake,
however embarrassing. What about more important theoretical claims like
Darwin's hypothesis of "pangenesis" as a mechanism of heredity (Darwin, 1868)?
Again, Darwin's view of life would have been easier to vindicate if the theory had
been affirmed, but none of his three essential postulates about the nature of
variation fell with the disproof of pangenesis, and the core commitments remained
intact, if unproven. What about the impact of major claims that turn out to be
basically true, Mendelism for example? We must make our judgment by assessing
their engagement with the core commitments. In the first decade of the 20th
century, most evolutionists invoked Mendelism as a saltational theory of
macromutation against the Darwinian core commitment to small-scale variation
(see Chapter 5). Later, largely through R. A. Fisher's analysis and the resolution of
the Mendelian vs. biometrician debate, macromutations were rejected, "ordinary"
small-scale variation granted a Mendelian basis, and Mendelism comfortably
reinterpreted as support for the same core commitment. Again, challenges and new
proposals must be judged and ranked by their engagement with the essence of a
reigning theory. Darwinism embodies a definable set of minimal commitments; all
great theories do and must.