developmental saltationist who accepted the selectionist basis of adaptive change
but felt that, at a sufficient relative frequency to be counted as important, the initial
steps of such changes may be larger than the pure continuationism of Darwinian
selection can admit. And an S3 cut might accept the full validity of
microevolutionary extrapolationism, but deny the subsidiary defense of progress
that Darwin grafted onto this apparatus (see Chapter 6) with ecological arguments
about plenitude and the priority of biotic over abiotic competition.
As a paleontologist and part-time historian of science by profession, my
reading of these important R-cuts arose from a macroevolutionary perspective
framed largely in terms of longstanding difficulties faced by Darwinism in
extending its successes for explaining small changes in palpable time into equally
adequate causal accounts for broader patterns and processes in geological history. I
have, in this effort, also benefited from my personal study of Darwin's life and
times, and especially the late 19th century debates on mechanisms of evolution (as
promulgated largely by professionals who could neither fully understand nor
accept the radical philosophical commitments underlying Darwin's view). This
historical study allowed me to grasp the continuity in basic themes from Darwin's
own formulation, through these foundational debates, right down to the major
theoretical struggles of our own time. An appreciation of this continuity allowed
me to discern and define the distinctively Darwinian view of life.
But I recognize only too well that every strength comes paired with
weaknesses. In my case, a paleontological focus leads me into relative ignorance
for an equally important locus of reform in the structure of Darwinism—increasing
knowledge of the nature of genomes and the mechanics of development. (I try to
cover the outlines of important theoretical critiques from this "opposite" realm of
the smallest, but the relative weightings in my text reflect my own varying
competencies far more than the merits of the cases. For example, although I do
discuss, and perhaps even adequately outline, the importance of Kimura and King's
neutralist theory in questioning previous assumptions of adaptationist hegemony, I
surely do not give an appropriate volume of attention to this enormously important
subject.)
Nonetheless, I hope that I have managed to present an adequate account of the
coordinating themes that grant such interest and coherence to modern
reformulations of the structure of evolutionary theory. Such thematic consistency
in revision becomes possible largely because Darwin himself, in his
characteristically brilliant way, tied the diverse threads of his initiating argument
into an overall view with a similarly tight structure—thus granting clear definition
to his own commitments, and also permitting their revision in the form of an
equally coherent "package." I would argue, moreover, and without wishing to
become extravagantly hagiographical (for I wrote this book, after all, primarily to
discuss a critique and revision of strict Darwinism), that our modern sense of
limitations in the canonical version arises from decisions that Darwin made for
tough and correct reasons in the context of his initiating times—reasons that made
his account the first operational theory of evo-
Defining and Revising the Structure of Evolutionary Theory 23