468 THE STRUCTURE OF EVOLUTIONARY THEORY
theory of natural selection provides no rationale for progress because the theory
speaks only of adaptation to changing local environments. (The morphological
degeneration of a parasite may enhance local adaptation as surely as any intricate
biomechanical improvement in a bird's wing.) Moreover, Darwin regarded the
banishment of inherent progress as perhaps his greatest conceptual advance over
previous evolutionary theories—and he said so, often and forcefully, as in this
epistolary comment, previously cited on page 373, to the American progressionist
paleontologist Alpheus Hyatt on December 4, 1872: "After long reflection I cannot
avoid the conviction that no innate tendency to progressive development exists" (in
F. Darwin, 1903, vol. 1, p. 344).
On the other hand, Darwin was not prepared to abandon his culture's central
concern with progress, if only to respect a central metaphor that appealed so
irresistibly to most of his contemporaries—that if the history of life embodied
predictable advance, then imperial expansion and industrial growth might be
validated, at least by analogy, as the inherent consummation of Victorian desire
and destiny, and not merely as an odd and ephemeral bump on the surface of
history. And so Darwin penned other statements with equal assurance, as in this
famous comment at the close of the Origin: "As natural selection works solely by
and for the good of each being, all corporeal and mental endowments will tend to
progress towards perfection" (1859, p. 489). Both opinions appear prominently and
often in Darwin's writing, and they do not jibe.
This ambivalence on the specific question of progress highlights a broader
issue at the center of Darwinism. Amidst the various meanings of Lyell's
"uniformitarianism," one concept has been judged as paramount by many scholars
(notably Rudwick, 1969): "non-progressionism" or uniformity of state—the
proposition that the earth remains in a dynamic steady-state of constant, pulsating,
cyclical change without direction: a strange kind of ahistoricism at the heart of
ceaseless motion. Darwin owed a profound intellectual debt to Lyell, including far
more than the expropriation of a geological stage to support the play of natural
selection (see both Chapter 2 and later sections of this chapter). By transfer and
analogy, Lyellian uniformity also provided a methodology for the general
formulation and application of natural selection itself. Lyell's view of change gave
Darwin a framework not only for the obvious features of gradualism,
incrementalism, and extrapolationism (as often noted), but also for the less
recognized ahistoricism of evolutionary mechanics. The bare bones of natural
selection supply no vector for the pathway of life: environments change in their
non-directional manner, and organisms respond in a continuous dance of local
adjustment.
But the history of life includes some manifestly directional properties—and
we have never been satisfied with evolutionary theories that do not take this feature
of life into account (see Gould, Gilinsky and German, 1988). (Indeed, the
stubbornly vectorial properties of paleontological change eventually led Lyell to
surrender this key aspect of uniformity in later editions of the Principles of
Geology—the most significant alteration of his intellectual ontogeny; see Gould,
1987b.) Darwin felt that natural selection could not be accepted