Species

Historical Summary and Conclusions 273

of the origination of new species. After this, there was a “species problem,” in which
various attempts were made to identify the genetic substructure of species. I date the
changeover to Poulton’s essay in 1903.
There never was a morphological species tradition as such, apart from the use of
morphology to identify species, and this continues today. Moreover, Idealism and
Morphology are distinct programs—not all morphologists are idealists (and hence
not all who rely on morphology are Platonists).
Species have always been understood to involve deviation from the type, from
Aristotle through to the modern era.
Type and essence are distinct ideas in biological history. Types can have varia-
tion, while essences cannot. Systematics has always used the type concept and a
“method of exemplars,” but rarely has it used essences as anything but a useful set
of diagnostic keys or as an aid to identication. Essence can be understood as a
formal notion—one used in description, denition, or identication—or it can be
understood to be a material notion—in which the essence causes the thing to be
what it is. Many biologists followed Locke in supposing that the Nominal (formal)
Essence was not the Real (material) Essence. There is no substantial material essen-
tialism in natural history or biology until after Darwin, if then. What there is, is
probably a reaction to Haeckel and the “evolutionists” who followed Schopenhauer
and Nietzsche, and largely relies upon the revival of Thomism after Vatican I. There
is a minor tradition, scientically speaking, of Neo-Thomist-inspired scientic mate-
rial essentialism from around 1870 to the end of the 1960s.
The Synthetic Darwinians generated and promoted a history of species before
Darwin as essences based upon a misreading of the (mostly logical and metaphysi-
cal) sources and applying them incorrectly to biological cases. Scientists often use
history as part of a program to promote their current scientic views, either by
demonizing their opponents in proxy or by demonstrating that they are the culmina-
tion of a progressive historical process of discovery. This is not restricted to either
side of any debate. Whiggism is rife in textbook histories.
The overall problem of species derives from its neo-Platonic history as a top-
down category of the logic of classication.^2 Modern taxonomy works in the oppos-
ing direction, beginning with the organisms, the individuals in the medieval system,
and thence to lineages, populations, and then species. Species in biology are the
result of inductively generalizing from individuals, rather than dividing general con-
ceptions into subaltern genera to reach the inmae species. We still desire to treat
species as a natural kind term, and hence to nd essential features that dene all and
only those taxa. Between-species synapomorphies are not like this; all they have in
common is that they keep lineages distinct (either causally or cognitively, the onto-
logical and the epistemic sides of this issue). They necessitate a bottom-up classica-
tion logic, or perhaps better, an in media res logic.^3 The reason I have made such play
with cladistic conceptions of classication in this work is that cladistic classication
is, depending how you interpret the matter, either a prolegomenon to induction, or
an act of induction in itself. Bottom-up classication involves projectable inductive

(^2) Boodin 1943.
(^3) Ghiselin 1997, 182ff.