Species

14 Species

cause of those faculties,^54 that for which things are generated. This forms the founda-
tion for the later Great Chain of Being tradition, and for the initial classications and
explanations of Cesalpino and Bauhin.^55
Aristotle has thus developed what we might think of as “science by denition.” If
one can dene the proper attributes of a thing, and what divides it from other univer-
sals, then one has understood and explained it. All those who attempt this method of
science prior to the seventeenth century are in effect practicing Aristotle’s method.
As a result, the terms genos (genus) and eidos (species) come to have several senses
based on the notion of differentiating out the special classes from the general. This
has given some historians of biology, particularly those writing from a modern sci-
entic perspective, considerable trouble.
Two issues arise. One is whether Aristotle thought that species were immutable,
and the other is whether Aristotle was an essentialist with respect to species. Lennox
holds that Aristotle did not depend on species being eternal in the biological sense,
that they were not xed.^56 They could come into being and pass away. But the kinds
(genē) do not come into being and pass away.^57 They are formed in virtue of having
the differentia that distinguish them from their superordinate genus. To this extent,
then, he is an essentialist and a xist of kinds. But I do not think it is correct to
saddle him with being a species (biological species) xist. In a telling passage in
Generation of Animals II.1, he notes that while individuals cannot be eternal, as they
are subject to generation and corruption, he admits that if anything can be eternal on
earth, it is the eidos of men and animals.

These are the causes on account of which generation of animals takes place, because

since the nature of a class [genous] of this sort is unable to be eternal, that which comes

into being is eternal in the manner that is open to it. Now it is impossible for it to be so

numerically, since the “being” of things is to be found in the particular, and if it really

were so, then it would be eternal; it is, however, open to it to be so specifically.^58

Note that he admits only the possibility rather than the necessity. Later, we will

consider the rise of the “Aristotelian essentialism” story, but a key aspect of the

ascription of taxic (that is, biological) essentialism to him rests on his distinction

between the proper and accidental properties of things.

THE TRADITION OF THE TOPICS

In his Categories, sometimes called the Topics, Aristotle reduced the number of

things that might be said of any thing to ten “topics” (τόποι, topoi, “places”):^59

(^54) 415 b9 –27.
(^55) Sachs 1890.
(^56) Lennox 1987, 2001.
(^57) Lennox 2001, 154.
(^58) Aristotle 1942, 731b730–733@131. Note that the term translated as specifically is ginomenon (as
produced, or as born), which is related to genos, not eidei (see footnote b of that page).
(^59) 1b25–2a4.