The Fruitful Facets of Gabon's Polyhedron 343
century thought (lest this section become a multivolumed book in itself). I will,
instead, commit the primary historical "sin" of self-serving retrospection, and focus
on those critiques of creativity that stressed formalist or structuralist themes now
relevant in modern reformulations of evolutionary theory. Thus, I ignore several of
the most important currents in late 19th century debate, particularly the strong
Lamarckism of many thinkers, and the various threads of theistic and other forms
of finalistic directionality.
Since Darwin's essential trio of assumptions about variability—copious,
small, and undirected (see pp. 141-146)—does permit natural selection to act as the
creative force of change, non-Darwinian alternatives, by logical necessity, deny
one or more of these assertions. The diverse formalist theories of this chapter gain
conceptual unity in granting directional power to internal factors, and not only to
the interaction of environment with isotropic raw material. Darwinian claims for
the small size and nondirectional character of variations become the obvious
candidates for confutation—for formalist alternatives to these Darwinian bastions
grant directional power to internal causes (whereas a denial of the third claim of
copiousness only places limits upon natural selection without supplying any
substitute as a cause of change). Thus, in this late 19th century heyday of
alternatives to Darwinism, formalist and structuralist thought centered upon claims
for the evolutionary importance of saltational and directional variation.
The most striking model and epitome for this formalist opposition derives
from a source that will strike many evolutionists as anomalous or paradoxical—
Darwin's brilliant and eccentric cousin Francis Galton. (The two men shared
Erasmus Darwin as a grandfather, surely the most eminent member of the family
before Charles himself.) Galton did study continuous variation extensively, and he
therefore gained a reputation as guiding spirit for the leading biometricians,
Pearson and Weldon. Moreover, his long-term trumpeting of eugenic improvement
also promoted the assumption that he favored insensibly gradual and continuous
change in evolution.
But Galton, a pluralist in his views on evolutionary causality, viewed
discontinuous variation as even more efficacious. Echoing Huxley's frequent plea
to Darwin for a larger permissible size in useful variants (advice that Darwin
explicitly rejected because he understood so well that the creativity of natural
selection would be seriously compromised thereby), Galton wrote (1889, p. 32)
that evolutionary theory "might dispense with a restriction for which it is difficult
to see either the need or the justification, namely, that the course of evolution
always proceeds by steps that are severally minute, and that become effective only
through accumulation. That the steps may be small and that they must be small are
very different views; it is only to the latter that I object."
We all recognize Galton's main contribution to the study of continuous
variation in his recognition and elucidation of the crucial concept of regression
toward the mean. But Galton did not interpret regression in a modern genetic light.
For him, regression guaranteed that continuous variation could not yield
progressive evolutionary change, because all favorable extremes