Species

270 Species

a basic term for such kinds. However, it is worth noting that in order to accommo-
date the rising number of discovered species during the age of exploration (or rather
the age of colonial expansion), they permitted Aristotle’s notion of new species by
hybridization to have greater play, along with spontaneous generation for species
without lungs such as insects and worms.
With Bacon, we move from an immediate generalization of the universals from
observed instances, and a subsequent top-down division of things, to the inductive
construction of increasingly broader generalizations. He too allows for deviations
and variations in species and other taxa, and Locke proposes that not only is there
biological variation, but that species (sorts) themselves are conventional names we
use to communicate easily. Nevertheless, he did allow for a real essence, but it is one
that cannot be dened or even discovered. Leibniz was more optimistic; Kant even
more pessimistic.
Kant rejects Leibniz’s view of the law of completion (principle of plenitude) and
argues that nature is discretely divided, and he too uses a generative conception of
species. Although the traditional logic survives until the institution of set theory in
the nineteenth century, even Mill is able to twist it to serve biological realities. Both
the logical tradition before Darwin and after, in his own country, allow for a differ-
ence between essentialist logical species and typological biological ones.
There is everywhere a remarkable lack of the sort of essentialism that Mayr and
others believe permeated this period and its philosophy. While we see typology,
when it comes to dealing with biological organisms, most of the time there is no
insistence upon essences, and sometimes there is an explicit exemption for biological
species of any knowable essence.
The major break with the classical notions of species from the tradition of
“universal taxonomy,” as I have called it, came with the Baconian insistence that
instead of beginning classication with the universals, species of living things are
found by a process of ascending abstraction and generalization. Species have been
understood to be propagative forms, which I have here termed the generative concep-
tion, and in various degrees and emphasis this remained the basic conception until
the modern era. For this reason, the focus has been on seed, the fructative apparatus,
and the reproductive behaviors, according to then-current views on generation.^1 The
reason for a focus on species as units of biology derived from the medieval tradition
and the neo-Platonic revival of the seventeenth century, but this was richer than the
Received View supposes.
Many conceptions of species depended on, or were confounded by, the Great
Chain. In one respect, a species was whatever was lowest in generality, but in another,
species were conventions, or articial divisions, since not all variant forms are to be
found in a locality. Plenitudinous views expected that intermediate forms would be
found, and, right into the nineteenth century with Macleay and Swainson, some held
that while species might be discrete, there would be a continuity of form itself. There
was often a species regarded as most like the vanilla generic characters, the type

(^1) Hull 1967, 312 did quote Aristotle (De Anima 415a26) on the generation of like forms. He notes that
Aristotle and Theophrastus did deal with cases where breeding true did not result in like forms,
though. This was not emphasized in Hull’s later work.