180 THE STRUCTURE OF EVOLUTIONARY THEORY
(This issue arose for many environmental determinists in both creationist and
evolutionist camps. Buckland, and most of his catastrophist colleagues, maintained
their allegiance to life's increasing perfection by positing a directional history of
environmental change—increasing inclemency, for example, requiring
improvement in organic design to meet the growing challenge. This option was not
open to Lamarck, who espoused a steady state, non-directionalist geology.)
Yet Lamarck firmly advocated a taxonomic ordering of organisms by the
conventional scheme of increasing perfection in organization. This subject greeted
him on a daily basis, for he held the post of curator for invertebrates at the Museum
in Paris, and his yearly courses featured this organizing theme of linear order. (As
a pedagogic device, Lamarck usually started with humans, as the "highest"
creature, and then discussed the rest of nature as degradation from maximal
complexity. He defended this procedure, even in his evolutionary writings, as a
method for teaching, even though historical order had actually moved from simple
to complex—for he argued that one must understand the full and final possibilities
before grasping the imperfect and incipient beginnings.)
Lamarck argued that a second set of forces, distinct from the causal flow of
environment to organism, produced nature's other primary pattern of advancing
complexity. But this claim for an efficient and universal cause of progress
engendered another dilemma: why, on our present and ancient earth, do some
organisms still maintain the simplest anatomies? Why were these forms not pushed
up the ladder of complexity ages ago? Lamarck resolved this problem with the last
major argument of his full system—continuous spontaneous generation. New life
continues to arise from chemical constituents; these simple forms begin their
march up the ladder, while replacements at their lowly status continue to form
anew. (Thus, in a curious sense, as Simpson and others have noted, Lamarck's
evolutionary system operates as a grand steady state, even as any particular bit of
protoplasm moves on a historical path up the sequence. The ladder of life really
operates as a continuous escalator, with all steps occupied at all moments. The
simplest forms continue to arise by spontaneous generation from chemical
constituents formed by the breakdown of higher creatures upon their individual
deaths.)
Lamarck argued that his unconventional chemistry, emphasizing the role of
fire and the motions of subtle fluids, engendered these two central phenomena—
spontaneous generation and progress up the ladder—as consequences of deeper
physical principles. Lavoisier had destroyed the old quadripartite taxonomy of air,
water, earth, and fire in developing his theory of chemical elements. Lamarck
opposed the "new chemistry" by asserting the old taxonomy, and his own
distinctive claim for the primacy of fire. Much of Cuvier's disdain focused not on
Lamarck's biology, but on his allegiance to this antiquated chemistry.
Lamarck, who excelled in crisp assertion but not in clear exposition, never
fully specified why chemicals should aggregate to life, or what subtle motions