The Structure of Evolutionary Theory

At the same time, and fortuitously, my 10th and last volume of monthly essays in
Natural History Magazine, written without a single break from January 1974 to
January 2001, will also appear in print. In an eerie coincidence (with no meaning
that I can discern), my first technical book, Ontogeny and Phylogeny, appeared
exactly 25 years before, in 1977, also at the same time as my first book of Natural
History essays, Ever Since Darwin. This odd and twofold simultaneous
appearance, 25 years apart, of my best youthful efforts in the contrasting (but not
really conceptually different) realms of technical and popular science, and then of
my best shots from years of greater maturity in the same two realms, has forced me
to think long and hard about the meaning of continuity, commitment and personal
perspective.
My popular volumes fall into the explicit and well recognized category of
essays, a literary genre defined, ever since Montaigne's initiating 16th century
efforts, as the presentation of general material from an explicitly personal and
opinionated point of view—although the best essays (literally meaning "attempts,"
after all) tend to be forthright in their expression of opinions, generous (or at least
fair) to other views, and honest in their effort to specify the basis of authorial
preferences. On the other hand, technical treatises in science do not generally
receive such a license for explicitly personal expression. I believe that this
convention in technical writing has been both harmful and more than a bit
deceptive. Science, done perforce by ordinary human beings, expressing ordinary
motives and foibles of the species, cannot be grasped as an enterprise without some
acknowledgment of personal dimensions in preferences and decisions—for,
although a final product may display logical coherence, other decisions, leading to
other formulations of equally tight structure, could have been followed, and we do
need to know why an author proceeded as he did if we wish to achieve our best
understanding of his accomplishments, including the general worth of his
conclusions.
Logical coherence may remain formally separate from ontogenetic con-
struction, or psychological origin, but a full understanding of form does require
some insight into intention and working procedure. Perhaps some presentations of
broad theories in the history of science—Newton's Principia comes immediately to
mind—remain virtually free of personal statement (sometimes making them, as in
this case, virtually unreadable thereby). But most comprehensive works, in all
fields of science, from Galileo's Dialogo to Darwin's Origin, gain stylistic strength
and logical power by their suffusion with honorable statements about authorial
intents, purposes, prejudices, and preferences. I cannot think of a single major
book in natural history— from Buffon's Histoire naturelle and Cuvier's Ossemens
fossiles to Simpson's Tempo and Mode, and Mayr's Animal Species—that does not
include such extensive personal information, either in explicit sections, or inserted
by-the-by throughout. (Even so abstract a presentation as R. A. Fisher's Genetical
Theory of Natural Selection gains greatly in comprehension through its long and
final, if in retrospect regrettable, section on the author's idiosyncratic eugenical
views about human improvement.) I have included personal discussion throughout
this text, but let me also devote a few explicit pages to the
Defining and Revising the Structure of Evolutionary Theory 35