Species

302 Species

INTRINSIC BIOLOGICAL ESSENTIALISM

The second new essentialism is Michael Devitt’s,^55 which he called Intrinsic Biological

Essentialism (IBE^56 ). Devitt defines essential properties thusly:

A property P is an essential property of being an F iff anything is an F partly in virtue

of having P. A property P is the essence of being an F iff anything is an F in virtue of

having P. The essence of being F is the sum of its essential properties.^57

This is one of a number of definitions of what makes an essential set of properties

given in the literature. More broadly, Brian Ellis defines it as

The real essence of any natural kind is a set of properties or structures in virtue of

which a thing is a thing of this kind, and displays the manifest properties it does.^58

The difference between intrinsic and origin essentialism is that the properties that

define IBE are, as the name indicates, intrinsic to the species. However, they need

not be intrinsic to each member of the species; that is, the essential properties need

not be microstructural essences. The essentialist argument is nicely summarized by

Wilson and co-authors:

... a kind’s essence is universally instantiated by members of the kind, is causally

responsible for that kind’s typical traits, and is explanatorily salient in accounts of

those traits. If biological kinds are intrinsically heterogeneous in the sense described

above, then there are no such universally instantiated traits, and so the causal and

explanatory roles played by putatively corresponding essences do not exist.^59

Devitt offers the argument that “being a member of a certain taxon is more than
informative, it is explanatory,” and “when biologists group organisms together under
some name on the basis of observed similarities, they do so partly on the assumption
that those similarities are to be explained by some intrinsic underlying nature of the
group.”^60 In other words, biological practice is essentialist both methodologically
and epistemologically.^61 Devitt distinguishes between the question of what it is for
F to be a species, and what it is for an organism to be a member of F. He rejects the
relational (origin) account of species that Griffiths presented, as it makes all mem-
bers of several species with a shared common ancestor members of a single species.
Devitt’s essentialism permits both gradual change and arbitrariness of delimita-
tion, so long as there are cases where species are clearly distinct in their underlying

(^55) Devitt 2008, 2011.
(^56) Not to be confused with Inference to the Best Explanation, Chapter 14, this book.
(^57) Devitt 2008, 345. See Dumsday 2012 for a discussion of these definitions.
(^58) Ellis 2001, 54. Ellis’ essentialism applies far more broadly than just biology; he intends it to apply to
physical, dynamic, kinds in general.
(^59) Wilson et al. 2 0 0 7, 193.
(^60) Devitt 2008, 352f.
(^61) This is similar to the views of Fitzhugh 2009.