The Modern Synthesis as a Limited Consensus 513
(p. x): "The deductions respecting Man are strictly inseparable from the more
general chapters."
I regard the conspiracy of silence about these chapters as both unscholarly and
overly fastidious. First of all, how can we justify silence about integral parts of an
important thinker's work because we now recoil at his beliefs? (Wagner's
antisemitism retains intimate linkage with his musical productions, but we cannot
ban such glorious operas.) Second, even if we wish to defend such posthumous
cleansing, Fisher's eugenics can only be judged as "garden variety" material for his
time, and not as especially benighted or vengeful. His visions of proper social
stratification may surely be judged elitist (scarcely a rare attitude for an Oxbridge
don in class-conscious Britain), but anachronistic exponents of modern political
correctness will appreciate other facets of his argument. (Fisher, for example,
cautiously advocates racial mixing for its role in increasing genetic variance,
thereby supplying more material at the right tail of the human distribution, even
though admixture with a "lower race"—Fisher did not espouse egalitarian beliefs!
—might depress the mean.)
But the central relevance of these final chapters lies in the consonance of
Fisher's eugenical argument with his commitment to a general and statistical
Darwinism. Fisher's eugenics provides our most interesting and incisive
affirmation of his evolutionary philosophy. Darwinian triumph must be measured
as differential reproductive success, statistically defined in large populations—not
as particularistic victory for nifty bits of morphology (or mentality) in Tennyson's
world of "nature red in tooth and claw." Moreover, Fisher maintains that our
current pattern of degeneration arises from differentials in birth rate, not from
selective superiority in resisting death—so Darwinian "success" can only be
viewed as statistical leverage in components of reproductive advantage, not as
improvement in any social or vernacular sense: "Even the highest death-rate in this
period, that in the first year of life, must be quite unimportant compared with slight
differences in reproduction; for the infantile-death rate has been reduced in our
country to about seven percent of the births, and even a doubling of this rate would
make only about a third as much difference to survival as an increase in the family
from three children to four" (1930, p. 194).
Finally, this eugenical example illuminates the central Darwinian claim for
the power of slight statistical advantage. A truly effective, and truly Darwinian,
eugenics, Fisher argues, will focus on apparently tiny reproductive differentials,
and not on the elimination of rare and overt "saltations"—sterilization of the
genetically diseased or mentally defective, as in the programs favored by most
eugenicists who did not grasp the Darwinian imperative. We might regard small
differences in birth rates as trifling, and unlikely to exert much effect upon the
rapid time scales of human history. But anything that can be measured at all over
the minimal span of a generation or two translates to an enormous effect in
evolutionary time. Thus, the social promotion of relative infertility, however
"invisible" in comparison to the devastation of war or the progress of technology,
will yield an evolutionary degeneration far