The Modern Synthesis as a Limited Consensus 589
causes of evolution that either deny natural selection entirely, or demote Darwin's
preferred cause to insignificance. These alternative forces are, in any case, opposed
to—clearly not synergistic with—Darwin's principle of natural selection at the
organismic level.
The explicit, often vociferous, invocation of these critiques against
Darwinism set the primary agenda for scientific debate from the very beginning of
modern evolutionary theory. On the first leg, the Lamarck-Chambers tradition of a
primary force of progress (effectively inaccessible to empirical study), opposed to
a palpable cause of immediate adaptation (eminently operational for research, but
decidedly secondary in significance), acted as a major spur to Darwin's
development of a fully operational theory with causes working at a single and
accessible level. On the second leg, internalist notions of orthogenesis and saltation
denied creativity to natural selection and defined the major versions of late 19th
century anti-Darwinism. On the third leg, classical catastrophism became Darwin's
personal bete noire, an obstacle that he surmounted by allegiance to Lyellian
uniformity. Later in Darwin's career, the appearance of a similar threat in a
different guise—the claim for an earth too young to render the results of evolution
by natural selection in a gradualistic mode—led Darwin to characterize Lord
Kelvin as an "odious specter."
I believe that the historical tradition for using these critiques as supposed
confutations of Darwinism has engendered a great deal of unnecessary and
unproductive wrangling in our own time, as markedly different versions of the
same critiques needlessly evoke old fears. I also believe that we can find the way
to a better (and healing) taxonomy by following the lead of Kellogg's fine
presentation (1907), already much praised in this book. Kellogg, as previously
discussed (pp. 163-169), divided critical commentary about Darwinism into
arguments "auxiliary to" and "alternative to" natural selection—enlargements and
confutations, if you will. In the past, critiques of the Darwinian tripod have usually
been advocated in Kellogg's alternative, or destructive, mode—and a tradition for
quick (often ill-considered) and defensive reaction by Darwinians has developed
whenever the critical buzz-words rise again: rapid change, group selection, mass
extinction, directed mutation, for example. But all these critiques can also generate
powerful versions in Kellogg's auxiliary, or helpful and expansive, mode—as
Kellogg himself recognized when he classified Weismann's theory of hierarchy as
one of the two most significant auxiliary propositions of his time.
The older, alternative mode of these critiques did lead to a series of dead ends,
rightly rejected by the resurgent Darwinism of the Modern Synthesis. Older
versions of hierarchy (the first leg) foundered in the mysticism of super-organisms
and harmonious ecologies; constraint and laws of form (the second leg) became
mired in invalid macromutationism or lingering orthogenesis; catastrophic geology
(representing the third leg) languished in the failure of all proposed mechanisms
for global paroxysm. The old versions, freighted by the cultural bias of progress,
and rooted in false arguments for the demise of Darwinism, richly deserved the
rejection they received.