572 THE STRUCTURE OF EVOLUTIONARY THEORY
fireplace at night, to cite an androphilic metaphor of past and privileged
generations). Evolutionary theory is now essentially complete; we know how the
process works and now only need to supply some details. G. G. Simpson had
written in a 1950 essay (reprinted in Simpson, 1964, p. 14): "This general theory is
now supported by an imposing array of paleontologists, geneticists, and other
biological specialists. Differences of opinion on relatively minor points naturally
persist and many details remain to be filled in, but the essentials of the explanation
of the history of life have probably now been achieved."
The Chicago symposiasts continually asserted their agreement with this
confident consensus. Tinbergen spoke of "the all-pervading power of selection"
(1960, p. 609). Huxley (in Tax and Callender, 1960, volume 3, p. 45) defined the
future task of evolutionary biology as filling in the blanks: "We are no longer
having to bother about establishing the fact of evolution, and we know that natural
selection is the major factor causing evolutionary change. Our problems now
concern working out in detail how natural selection operates, defining what we
mean by 'increase of organization,' tracing the general trends that appear in the
course of evolution, and so on." He then described the range of phenomena that
selection can fashion—in short, everything that might happen in evolution! "It
produces branching; it produces increasing adaptation, improvement, progress, or
whatever you like to call it; and it produces horizontal persistence of branches, or
stabilization" (in Tax and Callender, 1960, volume 3, p. 139).
I argued in the last section that "hardening" of the Synthesis gains clearest
expression in an increasing faith that adaptation must be both the impetus and
result of nearly any evolutionary change. The 1959 symposia continually stress this
theme. Panadaptationism became a premise for Chicago's major panel discussion
on "the evolution of life," not an issue to be adjudicated by participants. Panelists
received a list of assumptions, including the statement that "transformation always
leads to adaptive or, better, teleonomic results" (in Tax and Callender, 1960,
volume 3, p. 109).
Confidence in adaptation grew so great that many symposiasts presented their
arguments in a "can't fail" manner, by delimiting a set of supposedly inclusive
outcomes, each validating adaptation for any conceivable result. * Mayr, for
example, argued that the general ecological rules of Bergmann and others enjoy
good adaptive explanations, but that the numerous exceptions also affirm
adaptation because local (and opposite) factors can override the
*But what scientific good can derive from a theory that includes no possibility of
refutation from within? (A Mormon friend once told me that archaeologists of his church
would either one day find direct evidence that the people of Mormon and Moroni had
migrated from the Near East and lived in the New World until the 4th century AD, which
would support the testimony of the Book of Mormon, or they would not find such
evidence, which would also support the doctrines of his church by illustrating God's
challenge to his people to keep faith in the absence of empirical support.) In such cases,
one can only suggest alternative theories from without, and try to persuade people of
good will that these alternatives provide better explanations for the purely empirical
evidence.