224 Species
dissolves.^85 But if there were no possibility of immersing it in water, would it remain
a soluble substance? We want to say so, but if we examine our intuitions, this is
because we know of other lumps of sugar that they have dissolved, and by analogy
with this lump, which has the same composition, and no reason to think otherwise,
so it too will dissolve. Propensities may also be interpreted as the average behavior
of a reference class in certain conditions,^86 but in this case it makes no sense to talk
about the propensity of an individual case (that is, of me and a fifteenth-century
woman in England). Either way, Mayr has a problem with potentials or propensities.
Mayr’s conception of species is, in the end, one of dispositions to behave in vari-
ous ways. Henry IV and I are of the same species because we are of the same “subs-
tance,” and were we in the same population, our genes could freely spread through
it. But this is what Mayr wants to object to; this smacks of essentialism, although,
as I have argued, it isn’t. In the meantime, let us note that Mayr tries to avoid coun-
terfactual claims of “would have interbred, if in the same (natural) population” with
his insistence on sympatry for full species-hood. It is a problem he makes largely for
himself, based on his conflation, I believe, of the epistemic and ontological aspects
of being a species. In this, he is not alone.
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(^85) Cf. Sober 1984, 76–78.
(^86) Hájek 2003.