Abstract of “Biological Species Are Natural Kinds”
This paper argues that typical biological species are natural kinds, on a familiar realist understanding of
natural kinds—pluralities of individuals across which certain properties cluster together, in virtue of the
causal workings of the world. But the clustering is far from exceptionless. Virtually no properties, or
property-combinations, characterize every last member of a typical species—unless they can also appear
outside the species. This motivates some to hold that what ties together the members of a species is
ability to interbreed, others that it is common descent. Yet others hold that species are scattered
individuals, of which organisms are parts rather than members. But not one of these views absolves us of
the need to posit a typical phenotypic profile. Vagueness is here to stay. Some seek to explain the
vagueness by saying species are united by “homeostatic property clusters”; but this view collapses into
the more familiar realist picture.