384 THE STRUCTURE OF EVOLUTIONARY THEORY
potentially valid challenge to Darwinism. The first and most important volume of
Whitman's monograph bears the title: "Orthogenetic Evolution in Pigeons."
Whitman provides our best example for disproving the false equation of
orthogenesis with some form of theistic teleology—the main source for current
derision, and for our failure to grasp the strengths and serious recommendations of
this approach. The link to teleology can be dismissed as not only wrong, but
entirely backwards. No case could be clearer than Whitman's, for he spent a
maximally distinguished career as one of the great mechanists of American
experimental embryology. He did not conceive orthogenetic trends as mystical
impulses from outside, but as mechanistic drives from within, based upon
admittedly unknown laws of genetics and embryology. Consider the last words of
his 1919 monograph (p. 194):
If we are to draw the line sharply between science and all transcendental
and telistic mysticism, we must regard the germ-organism as wholly
mundane in origin and nature. If the germ is a thing of evolution from
purely physical foundations—and any contrary assumption is a denial of
the evolution principle, then we may say that it is a self-building within the
limits of physical conditions, and just as truly autonomic in its form and
behavior as is the crystal. In the formation of a crystal self-determination is
ever present, and so it must be in the case of the organism.Orthogenesis therefore emerges as a favored a priori prediction of
deterministic science. Whitman's opening words strike the same theme with a
note of triumphal optimism:
Progress in science is better indicated by the viewpoints we attain than by
massive accumulation of facts. Darwin's perspective made him a prodigy in
the assimilation of facts and an easy victor in the greatest conflict science
has thus far had to meet. His triumph has won for us a common height from
which we see the whole world of living beings as well as all inorganic
nature; phenomena of every order we now regard as expressions of natural
causes. The supernatural has no longer a standing in science; it has
vanished like a dream, and the halls consecrated to its thraldom of the
intellect are becoming radiant with a more cheerful faith (1919, p. 3).Moreover, the particular character and personal history of Whitman's
mechanistic outlook suggested the specific form of his orthogenetic argument. His
work on cell lineages had mapped the fate of the earliest blastomeres, and had
indicated that the source of eventual organs could be specified even in minute and
formless clumps of initial cells. If embryos grew so predictably, why should
evolutionary change be devoid of similar order? Ontogeny, in other words, should
serve both as a model and a source for evolution—a joint vision of directional
change from within. Whitman, in fact, argued that ontogeny and phylogeny
represent the same essential process: "Development is the one word that seems to
me to best circumscribe the