Internalism and Laws of Form 257
as the old Unity of Type theorists held, but partnership with adaptation remains a
reasonable and minimal demand.
We may epitomize Darwin's brilliant reconstruction of causation in natural
history, the new dimension that he added, and the one that we need to reinsert, in
diagrammatic form. Pre-evolutionary theorists, entirely lacking the concept of
historical change, attributed created form to a dichotomous distinction of causes:
immediate and functional vs. deeper and architectural (Fig. 4-1). Darwin literally
added the dimension of history, but removed a previous axis of explanation by
redefining constraints of Unity of Type as consequences of past adaptation (ancient
Conditions of Existence)—Figure 4-2. Yet Darwin understood that he had not
abolished the concept of constraint in undermining the primary example—
homologies of Unity of Type—by real-location to the opposite camp. He therefore,
in the same passage, established a different domain for constraint, as a category
subservient to adaptation by the two standard arguments of relative frequency: the
spatial claim of limited room (nooks and crannies) and the temporal claim of
secondary status (sequelae to adaptation)—see Figure 4-3.
4 - 1. The standard pre-evolutionary and dichotomous conception of the causes of form as
working either by adaptation to immediate conditions of existence, or by manifestation of laws
of form that reflect unity of type.4 - 2. Darwin literally adds a third dimension of history for the explanation of form. But he greatly
devalues the domain previously ascribed to unity of type, admitting constraints of laws of form
only by redefining such similarities as homologies based on the inheritance of past adaptations,
and therefore adaptational in their origin and primarily due to the other (and now predominant)
domain of conditions of existence.