The Structure of Evolutionary Theory

(Michael S) #1

Internalism and Laws of Form 325


begins his treatise with an incisive argument, cutting to the heart of Paley's error in
ignoring relationships among organisms and speaking only of particular designs
and their individual excellences. Using Paley's own device of analogy to machines,
Owen undermines functionalism from within. Manufactured structures may be
individually optimized for their utility; therefore, such contrivances of human
technology will not be strongly constrained by homological elements of common
design. If organisms had been similarly built on mechanical principles of
optimality in adaptation, they would show more structural variation, and not be
morphologically clustered as varied manifestations of archetypes. The archetypes
themselves, therefore, cannot represent principles of merely functional design:


To break its ocean-bounds, the islander fabricates his craft, and glides over
the water by means of the oar, the sail, or the paddle wheel. To quit the dull
earth man inflates the balloon, and soars aloft, and, perhaps, endeavors to
steer or guide his course by the action of broad expanded sheets, like wings.
With the arched shield and the spade or pick he bores the tunnel: and his
modes of accelerating his speed in moving over the surface of the ground
are many and various. But by whatever means or instruments man aids, or
supersedes, his natural locomotive organs, such instruments are adapted
expressly and immediately to the end proposed. He does not fetter himself
by the trammels of any common type of locomotive instrument, and
increase his pains by having to adjust the parts and compensate their
proportions, so as best to perform the end required without deviating from
the pattern previously laid down for all.... Nor should we anticipate, if
animated in our researches by the quest of final causes in the belief that
they were the sole governing principle of organization, a much greater
amount of conformity in the construction of the natural instruments by
means of which these different elements are traversed by different animals.
The teleologist would rather expect to find the same direct and purposive
adaptation of the limb to its office as in the machine (1849, pp. 9-10).

Moreover, to stress the key methodological point, immediate utility does not
imply design for a current end. Complex shapes and anatomies, developed under
formalist rules of structural transformation, may find utility after arising for
nonadaptive reasons. The delayed fusion of mammalian skull bones may now
serve as a prerequisite for parturition through a small birth canal, but birds and
reptiles show a similar delay, and this "adaptive" feature did not arise "for" its
current and indispensable use in mammals:


I think it will be obvious that the principle of final adaptation fails to satisfy
all the conditions of the problem. That every segment in almost every bone
which is present in the human hand and arm should exist in the fin of the
whale, solely because it is assumed that they were required in such number
and collocation for the support and movements of that undivided and
inflexible paddle, squares as little with our idea of the simplest
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