Pattern and Progress on the Geological Stage 479
into the disabling paradox analyzed in Chapter 2: palpable phenomena are
unimportant; while important phenomena remain intractable. Lamarck
distinguished a lateral process of local adaptation from a linear force of progress.
Adaptation, as a local event of potentially rapid occurrence, could be observed, but
this diversionary change provided no insight into the orthogonal and more
important vector of progress through substantial time.
Darwin wanders on the fringes of the same dilemma. He identifies natural
selection as a force of local adaptation. He wishes to escape the Lamarckian
paradox of orthogonal causes by arguing for strict uniformity and extrapolation.
The palpable and local force of adaptation therefore becomes, by smooth
extension, the source of all evolutionary change at all levels. But how then could
Darwin render progress—an idea that we might dismiss today as a cultural bias
(Gould, 1996a), but that Darwin, as an eminent Victorian, did not wish to abandon
(see Richards, 1992; Ruse, 1996)? Natural selection cannot provide the answer all
by itself and without auxiliary principles, for this force must work in Lyell`s world
of non-directional uniformity. Natural selection, at the "bare bones" of its
mechanism, only builds adaptation to changing local environments; the principle
includes no statement about inherent directionality of any kind, not to mention
progress.
Darwin resolved this tug of war between the logic of his theory and the needs
of his century by invoking a particular ecological context as the normal stage for
natural selection. If most ecosystems are chock full of life, and if selection usually
operates in a regime of biotic competition, then the constant removal of inferior by
superior forms will impart a progressive direction to evolutionary change in the
long run. In opposition to most of his evolutionary predecessors (Lamarck in
particular), who postulated a higher (and impalpable) realm of causality to
encompass progress, Darwin stuck with his single level of immediate and testable
natural selection—and ensured progress by adding a boundary condition about the
state of ecology, rather than by devising an additional and untestable causal
apparatus. By this ingenious strategy, Darwin managed to have his cake of unified
theory at a single, accessible level, and also to satisfy his culture's hunger for
rationalizing progress.
Uniformity on the Geological Stage
Lyell's Victory in Fact and Rhetoric
I spoke in Chapter 2 of a "Goldilocks problem" in Darwin's views on the nature of
environment and geological change. Since Darwin uses "trial and error" (with the
organism proposing and environment disposing) as the chief metaphor in his
predominantly externalist theory of change, the outer environment (biotic and
abiotic) assumes a more important role in the theory of natural selection than in
most other evolutionary accounts of the 19th century. For Darwin, environmental
change must be neither too little, lest the external prod fail, nor too great, lest the
prod become a determinant in itself, thus demoting the role of the organism. In
practice, too little change only