previous explanatory schemes, not as pure additions to a former state of
acknowledged ignorance. Lamarck's evolutionary theory, known to anglophonic
readers as a first full account through the fair but critical descriptions of Lyell (in
Volume 2, 1832, of the Principles of Geology), and from Chambers's promotion in
the Vestiges of 1844, provided a context for Darwin's refutation. Darwin's single-
level theory, based on the full efficacy of locally adaptive changes at the smallest
scale, countered the only available alternative of Lamarckism by relocating the
major phenomenon that generated change and required explanation (local
adaptation for Darwin, general progress for Lamarck), and (far more radically) by
reversing the conventional Paleyan explanation for the good design of organisms
and the harmony of ecosystems (direct divine construction at the highest level vs.
sequelae of natural selection working at the lowest level of organismal advantage).
- Lamarck, a dedicated materialist with a two-factor theory of evolution as a
contrast between linear progress up life's ladder and tangential deflections of
diversity through local adaptation, has been widely misunderstood (and reviled),
both in Darwin's time and today, as a vitalist and pure exponent of "soft" or
Lamarckian inheritance (which he accepted as the "folk wisdom" of his day, and
invoked primarily to explain the secondary process of lateral adaptation). - Darwin's theory of natural selection shared a functionalist basis with
Lamarck in joint emphasis upon adaptation to external environment as the
instigator of evolutionary change. But the two theories differ most radically in
Darwin's citation of a single locus and mechanism of change—with the full range
of evolutionary results proceeding by natural selection for local adaptation of
populations to changing immediate environments, and all higher-level
phenomenology emerging by sequential accumulation of such tiny increments
through the immensity of geological time. By contrast, Lamarck advocated a two-
factor theory, with local adaptation as a merely secondary and diverging process
(and, as we all know of course, arising by soft inheritance of acquired features
generated by adaptive effort during an organism's life, rather than by natural
selection of fortuitous variation), set against a primary process of progressive
complexification up the ladder of life. Thus, Darwin embraced Lamarck's
secondary force (instantiated by a different mechanism), denied the existence of
Lamarck's primary force, and argued that the secondary force of local adaptation
also produced the large-scale results attributed by Lamarck to the primary force.
Thus, this first major debate between evolutionary alternatives contrasted
Lamarck's hierarchical theory with Darwin's single-level account. Hierarchy has
been an important issue from the start (although, obviously, modern versions of
hierarchical selection theory, advocated as the centerpiece of this book, bear no
relationship, either genealogical or ideological, to this false, but fascinating,
Lamarckian original). - Darwin explicitly rejected Lamarck's two-factor theory, correctly
identifying the disabling paradox that rendered the theory nonoperational: "what is
important cannot be observed or manipulated (the higher-level force of progress),
and what can be observed and manipulated (the tangential force of local
adaptation) cannot explain the most important phenomenon (progress
Defining and Revising the Structure of Evolutionary Theory 63