460 Robin O. Andreasen
poses a problem for typological definitions in systematic biology; the problem is
that, with the development of population biology, evolutionary theory no longer
uses the natural state model to explain variation within and continuity among
taxa [Sober, 1980]. To see why this is so, let us think about the model from the
perspective of contemporary genetics. It is the idea that all of the members of
a taxon (racial, specific, generic, etc.) share a common genetic essence that, in
conjunction with its natural environment, results in the natural phenotype for
that taxon. All other phenotypes are regarded as the result of interfering forces
and all other environments are regarded as perturbations of the system. The
problem is that the ideas of type and of deviation from type do not feature in
contemporary evolutionary theory. Contemporary evolutionary theory does not
distinguish between the natural phenotype for a given genotype and those that
are the result of interference — nor does it identify a natural environment for
a given genotype. Moreover, no particular genotype is privileged and viewed as
essential for a taxon. Instead all genotypes and environments are treated as being
on a par, and the phenotype of a given genotype is always described relative to an
environment.
A further problem with typological definitions in systematic biology has been
articulated by Michael Ghiselin [1974] and David Hull [1976; 1978]. Their argu-
ments were originally advanced against the typological species concept, but can
be generalized to show why typological definitions are problematic at any level in
the taxonomic hierarchy. According to Ghiselin and Hull, natural kinds defined
according to essentialist criteria are supposed to be spatiotemporally unrestricted
classes. They are defined by appeal to purely qualitative properties possessed by
all and only the members of a kind. As such, kind membership does not depend
on spatiotemporal or causal relations among the members of a kind. Systematic
categories, on the other hand, are best understood as spatiotemporally localized
historical entities. Most systematic biologists, for example, define taxa (at least in
part) in terms of the genealogical relations among organisms. Since genealogical
relations are not purely qualitative, Ghiselin and Hull maintain that essentialism
is the wrong view to take about biological classification.
It is important to stress that although essentialism was historically influential,
not all conceptions of race (common sense or scientific) are essentialist in nature.
With the development of contemporary evolutionary theory and the rise of popu-
lation genetics, the typological race concept was replaced by a population concept
of race. It is to this concept that I now turn.
3 THE GEOGRAPHICAL RACE CONCEPTAfter the downfall of the typological race concept, biologists began defining ‘race’
geographically. According to thegeographical race concept, a race is a geographi-
cally localized subdivision of a species that differs phenotypically and genetically
from other conspecific populations [Mayr, 1942]. Several features of this defini-
tion are worth noting. First, a single geographical race typically comprises several