Internalism and Laws of Form 253
in national styles. As a young man, Darwin adored Paley's Natural Theology (see
p. 116); later, in a courageous act of intellectual parricide, he constructed a theory
that subverted Paley's mode of explanation. But Darwin never abandoned Paley's
conviction that adaptation must be designated as the primary phenomenon of
natural history. Darwin remained true to an English tradition stretching at least as
far back as Robert Boyle and John Ray in the late 17th century of Newton's
founding generation for modern science, running through Paley, the Bridgewater
Treatises, Wallace, and Poulton in Darwin's own time, on to R. A. Fisher and
finally to E. B. Ford, A. J. Cain, and R. Dawkins in the later 20th century.
When we properly place Darwin in this lineage, a genealogy unfractured by
evolutionary theory, we can make sense of his fateful decision for resolving Unity
of Type vs. Conditions of Existence at the end of Chapter 6—a choice faithful to
Paley and the English tradition in reaffirming the primacy of adaptation. Darwin
writes, in words that define the causal basis of his theory (and continuing from the
previous quotation on p. 25):
On my theory, unity of type is explained by unity of descent. The
expression of conditions of existence, so often insisted on by the illustrious
Cuvier, is fully embraced by the principle of natural selection. For natural
selection acts by either now adapting the varying parts of each being to its
organic and inorganic conditions of life; or by having adapted them during
long-past periods of time: the adaptations being aided in some cases by use
and disuse, being slightly affected by the direct action of the external
conditions of life, and being in all cases subjected to the several laws of
growth. Hence, in fact, the law of the Conditions of Existence is the higher
law; as it includes, through the inheritance of former adaptations, that of
Unity of Type (1859, p. 206).Darwin's brilliant intellectual move clearly expresses the revolutionary impact
of evolutionary explanations against the previous range of creationist paradigms.
Creationist biology saw Unity of Type and Conditions of Existence, homology and
adaptation, as opposite, but equally contemporary (or timeless), poles in a
dichotomy of originating forces. Darwin literally added a new dimension to the
debate—the axis of history. (And no intellectual expansion can be more profound
than the introduction of a new dimension, orthogonal to previous modes of
explanation.)
Thus, in this passage, Darwin makes a stunningly simple suggestion to break
the impasse between Unity of Type and Conditions of Existence. (And yet, to be
able to see anything at all in this clear and simple light, one must first grasp the
revolutionary implications of evolution itself—the truly difficult intellectual
transition out of Paley's world!) To be sure, the homologies of Unity of Type do
not embody, and seem actively to oppose, current functions. Must Unity of Type
therefore represent a principle of order dichotomously contrary to adaptation? In a
world without history, where all features of organisms express their initially
created state, the answer must be "yes." But the addition of history, by a theory of
genealogical connection, permits