148 THE STRUCTURE OF EVOLUTIONARY THEORY
comes vitally important because selective quotation represents the most common
error made by evolutionists in interpreting his work and theory. The Origin, as a
volume of single authorship, maintains a stronger plot line and features fewer
inconsistencies than the Bible; but Darwin and the Good Lord do share the
common trait of saying something about nearly everything. Wrenched from
context and divorced from a crucial assessment by relative frequency, a Darwinian
statement can be found to support almost any position, even the most un-
Darwinian.
Since Darwin prevails as the patron saint of our profession, and since
everyone wants such a preeminent authority on his side, a lamentable tradition has
arisen for appropriating single Darwinian statements as defenses for particular
views that either bear no relation to Darwin's own concerns, or that even confute
the general tenor of his work. Thus, for example, Darwin wrote extensively about
variational constraint, and he maintained great interest in this topic (see Chapter 4).
But the logic of his work entails adaptive control of evolutionary change and
isotropy of variation as generally prevalent—and Darwin ultimately comes down
(as he must) on the side of these necessary underpinnings for natural selection.
Proper textual analysis requires that general tenor, not selective statement, be
presented. Two basic procedural modes, each with distinctive criteria, set the
framework for such textual analysis. The empirical mode makes its judgments of
importance by relative frequency and interconnectedness of statements.
Meanwhile, and simultaneously, the logical mode employs theoretical consistency
as an arbiter for judging the validity and power of the structure of argument. We
revere Darwin because he unfailingly manifested the two key traits of brilliance
and honesty. He knew where his arguments led, and he followed them relentlessly,
however unpleasant the consequences. We do him the greatest possible disservice
when we approach his work as a superficial grazer, searching for some particular
item of personal sustenance, while ignoring the beauty and power of general tenor
and logical entailment.
I raise this point here because abuse of selective quotation has been
particularly notable in discussions of Darwin's views on gradualism. Of course
Darwin acknowledged great variation in rates of change, and even episodes of
rapidity that might be labelled catastrophic (at least on a local scale); for how could
such an excellent naturalist deny nature's multifariousness on such a key issue as
the character of change itself? But these occasional statements do not make Darwin
the godfather of punctuated equilibrium, or a cryptic supporter of saltation (as de
Vries actually claimed, thus earning a unique and official rebuke from the
organizers of the Darwinian centenary celebration at Cambridge—see p. 416).
Gradualism may represent the most central conviction residing both within
and behind all Darwin's thought. Gradualism far antedates natural selection among
his guiding concerns, and casts a far wider net over his choice of subjects for study.
Gradualism sets the explanatory framework for his first substantive book on coral
reefs (1842) and for his last on the formation of topography and topsoil by
earthworms (1881)—two works largely devoid of