Species

260 Species

taxonomy” in virtue of the use of computers for the first time in systematics, basically

involves a cluster analysis of continuously varying characters in a Cartesian space of

n-dimensions (one dimension for each character or principle component) in the belief

that species will fall out as clusters that agglomerate in different ways. While Sokal

and Sneath generally give priority to the biological species concept, they note

In the absence of data on breeding and in apomictic groups. ..., the species are based

on the phenetic similarity between the individuals and on phenotypic gaps. These are

assumed to be good indices of the genetic position, although they need not be. ... In

this book it [the term “species”] will be used in the sense of phenetic rank....^35

Species are not unique in the phenetic approach; they are operational taxo-
nomic units (OTUs) just as above-species and within-species ranks are.^36 The phe-
netic view, though, is that species are not monotypic, and Sokal and Sneath define
a term, based on Beckner’s discussion,^37 monothetic, and its antonym polythetic,^38
to describe groups based on a single uniform set of characters versus those which
vary or have alternative characters; Wittgenstein’s family resemblance predicate is
explicitly adduced.^39

Species Deniers: Pure “Nominalism,” or Eliminativism

It is unfortunate that the alternative to the reality of species has been called “nomi-
nalism” by Mayr and others, because nominalism is a philosophical doctrine that
asserts that universals are not real, and species are not held by many to be uni-
versal terms. Strictly speaking, the individuals that “species nominalism” considers
real in opposition to species are individual organisms. However, in traditional logic
and metaphysics, a universal is not comprised of individuals so much as individu-
als instantiate the class.^40 Species are comprised of individuals under evolutionary
accounts, and so they are real to the extent that their components are (except under
ideal morphological views). It would be wrong to call these “nominalistic views”
simply because they are founded upon acts of naming. A species nominalism must
be directed to the category or rank of species, and must claim that there is no sense
in which that categorical term has any application. I therefore prefer to refer to spe-
cies deniers rather than to species nominalists.
Species deniers include Vrana and (Ward) Wheeler,^41 Pleijel,^42 a nd Hey.^43 I argued
above that Darwin was not a species denier, and that Buffon was only inconsistently
one. There are two varieties: conventionalism, and “replacementism,” the latter

(^35) Sokal and Sneath 1963, 30f; but see Sokal and Crovello 1970.
(^36) Op. cit., 121f.
(^37) Beck ner 1959.
(^38) Op. cit., 13–15.
(^39) Ibid., 14.
(^40) See Aaron 1952.
(^41) Vrana and Wheeler 1992.
(^42) Pleijel 1999, Pleijel and Rouse 2000.
(^43) Hey 2001b, 2001a.