269

11

Historical Summary

and Conclusions

It is time to sum up the major historical claims of this book. We have considered
several historical and several philosophical claims, each in the light of one another.
The biological conclusions are not mine to draw, but I can opine, and do in Section III.
From Aristotle through to the end of the Middle Ages and the Renaissance, the
notion of species has not remained static; Aristotle’s conventions and notions have
been modied. Mostly, they were modied by the neo-Platonists and especially
by Porphyry, who made Aristotle’s top-down classication scheme dichotomous
after the manner of Plato. Aristotle had opposed “privative” classication, classify-
ing in terms of what things are not, although the grander schemes of later writers
up to Lamarck had little problem with this, and happily classied groups such as
Invertebrata.
In the medieval scheme, the notion of genus and species did not involve xed
ranks; a species might in turn be a genus on its own. The only “absolute” ranks were
the summum genera, which represented in the Aristotelian tradition the universal
categories (topics, or topoi) from which all things were to be divided, and individu-
als. The nominalist issue whether these general terms were merely aspects of mental
categories or were real was alive and active well into the scientic period.
We nd in the Epicureans a generative conception of species as early as the fourth
century , and this recurs throughout the remaining discussions until the biologi-
cal tradition begins in the seventeenth century, and beyond. Essences, on the whole,
were not themselves thought of as necessary and sufcient criteria for membership
in species, and almost all writers admitted that there were deviations from the type.
The classical scheme was, however, almost always based on a top-down classica-
tion with a large admission of apriorism, until the collapse of the Universal Language
Project, and the rise of corpuscular philosophy, which rendered species secondary
qualities, or unknowable.
The Great Chain of Being meant that, depending on what emphasis was given
to the principle of plentitude and the principle of continuity, species were arbitrary
divisions in a plenum—sometimes logical, sometimes substantial and actual. The
specic nature of a member of a species was thought by Cusa to be a contraction
of the essence in that individual, but the ultimate reality, according to Cusa, is the
individual. A continuing battle between nominalists and realists (idealists in modern
terms) meant that there was a eld of alternate opinions. Variation is recognized to
be a fact within taxa from the fteenth century onward. Some, such as Ficino, held
that there was a species that was most representative of a genus, since other species
within the genus could play on variations of the generic theme, as it were.
The role of the Noachic story of the Ark effectively set up the problem of a low-
est kind in zoology, and as a result the term species (or genus) became anchored as