Pattern and Progress on the Geological Stage 481
describing an earth with a "just right," intermediate and dependable level of
geological change—have been extensively explored by scholars in the past thirty
years, and a general consensus has emerged (Hooykaas, 1963; Simpson, 1963;
Porter, 1976; and especially Rudwick, 1969; my own first publication developed
some of the same ideas independently and in the midst of some embarrassing
juvenilia—see Gould, 1965). Lyell presented a plethora of compelling and well-
presented evidence in his favor (gradualism does, after all, maintain at least a
respectable relative frequency among patterns of geological change); but he
triumphed as much by force of rhetoric, as by strength in documentation. Two
features of his rhetoric stand out for effectiveness.
- He invented a persuasive dichotomy, pitting uniformity and rectitude on
one side, against catastrophism and reaction on the other. Catastrophism, Lyell
argued, represented everything that had stifled the development of geology in a
dismal past—not only for the falsity of claims for worldwide paroxysmal change,
but also (and especially) for the sterility of a method that sought to explain the past
by causes that do not operate today on our slowly changing earth. In attacking his
cardboard version of catastrophism, Lyell penned some of the finest polemical
lines ever written by a scientist: "Never was there a dogma more calculated to
foster indolence, and to blunt the keen edge of curiosity, than this assumption of
the discordance between the former and existing causes of change." Catastrophist
geology became "a boundless field for speculation" that could "never rise to the
rank of an exact science." Lyell ended this volley with his most famous metaphor:
"We see the ancient spirit of speculation revived, and a desire manifested to cut,
rather than patiently to untie, the Gordian knot" (1833, volume 3, p. 6). - He took advantage of a "creative confusion" by extending the umbrella of
his single term "uniformity" over a variety of concepts with differing status—
thereby attempting to win assent for claims of dubious merit by giving them the
same name as other arguments that all scientists accept as valid. In particular, Lyell
stoutly defended—and defined as "uniformity"—a set of methodological
assumptions included within any full and proper definition of science (and
embraced with equal vigor by all serious catastrophists as well; see Gould, 1987b):
especially the spatiotemporal invariance of natural law and the actualistic principle
that hypothetical causes should not be postulated so long as observable modern
processes can generate the phenomenon in question, at least in principle. But Lyell
also extended the term "uniformity" to a set of empirical claims about the natural
world—testable statements that might be true or false, but emphatically cannot be
treated as methodological assumptions, necessarily embraced a priori as a license
to practice science at all. Two of these "substantive uniformities" influenced
Darwin greatly, and have echoed loudly through the 20th century as well:
gradualism, or uniformity of rate (especially the production of large-scale
phenomena by accumulation of ordinary, daily effects through immense stretches
of time); and non-directionalism, or uniformity of state (the empirical pattern of
ceaseless, often cycling modifications, without vectors of directional change).
Lyell eventually abandoned uniformity of state, when he finally became
convinced,