268 THE STRUCTURE OF EVOLUTIONARY THEORY
and rejects this last challenge with three arguments that, taken together, develop
his strongest case for adaptationism (the first two remain in prominent use today):
- Formalists do not deny the evident utility of most organic structures. The
focus of their argument, rather, rests upon a claim for temporal and causal primacy
(homology based upon historical order for evolutionists, or similarity based upon
repeated themes in manufacture for creationists). Adaptationists hold that
structures must evolve or be fashioned for utility: functional needs come first, and
form follows. Formalists argue, on the other hand, that morphology may arise for
reasons other than use, with later "uptake" of function as subsidiary: that is, form
comes first, and organisms may then discover usages. In a remarkable passage,
showing his grasp of this fundamental alternative (now being reasserted as the
basis for revival of interest in constraint among modern evolutionists), Paley
admits that the formalist argument must be acknowledged as "intelligible": "To the
marks of contrivance discoverable in animal bodies, and to the argument deduced
from them, in proof of design, and of a designing Creator, this turn is sometimes
attempted to be given, viz. that the parts were not intended for the use, but that the
use arose out of the parts. This distinction is intelligible. A cabinet-maker rubs his
mahogany with fish-skin; yet it would be too much to assert that the skin of the
dogfish was made rough and granulated on purpose for the polishing of wood, and
the use of cabinet makers" (p. 72).
Paley's refutation invokes the classic response: the formalist argument will
work for simple structures like fish-skin, but not for complex organs, composed of
multiple parts, all apparently adjusted for current function. "Is it possible to believe
that the eye was formed without any regard to vision; that it was the animal itself
which found out, that, though formed with no such intention, it would serve to see
with; and that the use of the eye, as an organ of sight, resulted from this discovery,
and the animal's application of it?" (p. 73). - The first argument epitomizes a conceptual mainstay of formalism, but the
empirical foundation of structuralist morphology has always depended more
strongly upon correlation among parts of an organism, buttressed by the inference
that structural relations, rather than utility, establish the linkage. Again Paley
provides the classic functionalist refutation, still prominently in use. The
correlations, he argues, do not arise by formal necessity, or "laws of growth," but
as coordinated adaptations, each separately useful and required for good design.
Swans have long necks and webbed feet for reasons of common function, not
"necessary connection": "The long neck, without the web foot, would have been an
incumbrance to the bird; yet there is no necessary connection between a long neck
and a webfoot. In fact they do not usually go together. How happens it, therefore,
that they meet, only when a particular design demands the aid of both?" (p. 293).
Paley then discusses a favorite example of British adaptationists since John
Ray, and a pest in British gardens from time immemorial: the mole. "From soils of
all kinds the little pioneer comes forth bright and clean. Inhabiting