970 THE STRUCTURE OF EVOLUTIONARY THEORY
populations without essences (and even without abstractions, like mean values, to
act as preferred or defining states) might break through a powerful and
constraining prejudice, ultimately rooted in Platonic essentialism, that leads us to
search for chimaerical idealizations as ultimate standards of comparison in the
definition and evaluation of artistic "style." Kuhn writes, now viewing styles as
paradigms and paradigms as higher level individuals like biological species (pp.
208 - 209): "Conceivably the notion of a paradigm as a concrete achievement, an
exemplar, is a second contribution [of my book]. I suspect, for example, that some
of the notorious difficulties surrounding the notion of style in the arts may vanish if
paintings can be seen to be modeled on one another rather than produced in
conformity to some abstracted canons of style."
Punctuated equilibrium represents just one localized contribution, from one
level of one discipline, to a much broader punctuational paradigm about the nature
of change—a worldview that may, among scholars of the new millennium, be
judged as a distinctive and important movement within the intellectual history of
the later 20th century. I am pleased that our particular formulation did gain a
hearing and did, for that reason, encourage other scholars over a wide range of
scientific and nonscientific disciplines (as illustrated in this chapter) to consider the
larger implications of the more general punctuational model for change. I am
especially gratified that many of these scholars did not just borrow punctuated
equilibrium as a vague metaphor, however useful, but also understood, and found
fruitful, some of the more specific "conjoints" distinctive to the level and
phenomenon of punctuated equilibrium, but also applicable elsewhere. For the
punctuational paradigm encompasses much more than a loose and purely
descriptive claim about phenotypes of pulsed change, but also embodies a set of
convictions about how the structures and processes of nature must be organized
across all scales and causes to yield this commonality of observed results. Only in
this sense— punctuated equilibrium as a distinctive contribution to a much larger
and ongoing effort—can I understand Ruse's gracious reappraisal of his initial
negativity toward punctuated equilibrium: "Grant then that there is indeed
something going on that looks like a paradigm (or paradigm difference) in action.
People (like my former self) who dismissed the idea were wrong—and missing
something rather interesting to boot" (Ruse, 1992, p. 162).
From the more restricted perspective of the aims of this particular book, I can
at least assert that punctuated equilibrium unites the three definitive themes of this
volume—the three legs of my tripod of support for an expansion of Darwinian
theory, thereby leading me to conclude that an empirically legitimate and logically
sound structure does encompass and unite these three arguments into a coherent
and general reformulation and extension of the Darwinian paradigm: the
hierarchical theory of selection on leg one, the structuralist critique of Darwinian
functionalism and adaptationism on leg two, and the paleontologist's conviction
(leg three) that general macroevolutionary processes and mechanisms cannot be
fully elucidated by uniformitarian