506 THE STRUCTURE OF EVOLUTIONARY THEORY
1922: "faith has given place to agnosticism" (see p. 412 for the full quote). The
first rumblings of synthesis had already occurred. As the most obvious and
important example, Fisher's pivotal 1918 paper on "The Correlation Between
Relatives on the Supposition of Mendelian Inheritance" had demonstrated the
potential Mendelian (polygenic) basis for the small-scale, continuous variation that
Darwinians had always identified as the primary source of evolutionary change—
and that the early Mendelians had either ignored as supposedly non-particulate, or
denigrated as evolutionarily insignificant (see pp. 429-431 on de Vries's attitude).
Fisher's demonstration established a basis for resolving the increasingly fruitless
debate between "biometricians" (Darwinian supporters of continuous variation)
and "Mendelians" (upholders of saltational change, in the first evolutionary use of
principles that would later blend with Darwinism)—a seminal, if ultimately barren,
dichotomy in early 20th century biology. By using the principles of one side
(Mendelian particulate inheritance) to explain the supposedly contradictory
phenomena of the other (continuous and isotropic variation in phenotypes)—and
then by banning the opposite (saltational) phenomena originally attached to the
principles—Fisher staged a brilliant coup that surely deserves the label of
"synthesis."
If Bateson had fallen a bit behind the times by 1922, he did accurately record
the near anarchy that had prevailed in the study of evolutionary mechanisms just a
few years earlier. Using Kellogg's (1907) framework, as I have done throughout
this book (see pp. 163-169 for an account and rationale), we may classify attitudes
outside the central core of Darwinism either as helpful expansions or as
contradictory substitutions—auxiliaries and alternatives in Kellogg's terminology.
Kellogg identified three major alternatives to Darwinism—Lamarckism,
saltationism and orthogenesis. At the 1909 celebrations for Darwin's centennial, all
three alternatives enjoyed substantial support, probably equal in extent, and in the
reputation of leading supporters, to the popularity of Darwinism itself. As a
supreme and well known irony, the original impact of the Mendelian
rediscovery—the ultimate source of restriction and synthesis—had only increased
the range and intensity of evolutionary debate by revivifying the saltational
alternative and thus augmenting the roster of major challenges to Kellogg's triple
threat.
Clearly, the state of evolutionary theory required restriction for further
advance—either a settling upon one of the four contenders (Darwinism plus the
three challenges), or a new formulation. The first phase of the synthesis
accomplished this goal in three major moves: (1) by choosing the Darwinian
central core as a proper and fundamental theory; (2) by reading Mendelism in a
different way to validate, rather than to confute, this central core; and (3) by
utilizing this fusion to ban the three alternatives of Lamarckism, saltation, and
orthogenesis.
Darwinism is a functionalist theory with an operational core that must place
primary weight upon building adaptation by the mechanism of natural selection
(see Chapters 2 and 4). In logic and principle, therefore, the theory could be
confuted in either of two ways: by affirming an alternative mechanism