Species

284 Species

(15) Occupancy of a perhaps broad and flexible niche (in the sense of a perhaps

arbitrarily bounded part, or even disjoint parts, of the [biotic and abiotic]

environmental hyperspace) different from that of any sympatric species.

(16) Ultimate regulation of population or metapopulation density being causally

different from that of any sympatric species.

All of these properties are of species taxa, not of the species category, which is

merely the set of all species .... The list is very heterogeneous, as it should be, but all

the attributes are ontic rather than epistemic.^2

In recent years, microbiology and virology have added various issues to the
explananda of the species problem, such as lateral genetic transfer, endosymbiosis,
community formation, and so forth. These, then, are the key issues that the problem
of species must address. As science has observational data that it seeks to explain,
philosophy has criteria that it needs to explain under unified concepts, or to dissolve
the concepts as being non-unifiable.
Van Valen goes on to argue that Beckner’s notion of a polytypic set^3 provides the
best resources for addressing the problem, but this is getting ahead of ourselves. For
now, let us note that polytypy, recast by Sneath and Sokal as a polythetic set, is a
philosophical notion. Philosophy is unavoidable even by scientists.
In fact, Beckner’s book began what is now understood as the modern discipline
of the philosophy of biology. Hull was influenced by him, as was Ruse. Nevertheless,
philosophical treatments of biology are of a long lineage,^4 including Dobzhansky’s
1935 paper “A critique of the species concept in biology,” published in Philosophy
of Science.^5 That noted, though, the modern discipline begins in the 1960s, and the
keystone paper that began it is Hull’s 1965 paper, written a mere five years after
Beckner’s book was published, “The effect of essentialism on taxonomy—two thou-
sand years of stasis,” and the key issue was species.
As we have seen, the essentialism story was instigated by Hull taking Popper’s
view of Aristotle, together with Cain’s 1958 paper, as being history. This found its
way into orthodoxy for the next fifty years through the advocacy of, among oth-
ers, Ernst Mayr. And once introduced in that fashion, philosophy became crucial to
the species problem, as essentialism was a long-standing topic in metaphysics and
epistemology.
It is now consensus among philosophers of biology, and many biologists, that
essentialism is contrary to biological reality. In large part, this is because of Mayr’s
authority and his notion of population thinking.^6 Divorced from the essentialism
story, however, the arguments in favor of populations as the “units” of Darwinian

(^2) Van Valen 1988, 51.
(^3) Beckner 1959, 23–25. Beckner was directly influenced by Wittgenstein’s “family resemblance” notion
in the Philosophical Investigations [Wittgenstein 1968, §67], but also the notion of a polytypic species
in biology [Van Valen 1988, 53].
(^4) For example, Smellie 1790, Whewell 1840, Oken 1847, Goodsir 1868, Papillon 1875, Spencer 1884,
Bailey 1896, Johnstone 1914.
(^5) Dobzhansky 1935.
(^6) For an excellent treatment of the notion of populations in a Darwinian context, see Godfrey-Smith

2009. See also Queller 2011.