Species

288 Species

Individual, Cohesive, or Concrete

There is a major equivocation on the term “individual” that causes some confusion
in the literature. There are three kinds of individual that one finds in the discussions,
and they are not always disambiguated by the authors.
Metaphysical or logical individuals (“Particulars”): These are entities that are
not classes; that is, which are particulars. A class is defined (in my preferred meta-
physics^22 ) as the denotation of a non-restricted predicate. The metaphysical aspect of
“individual” sensu Ghiselin/Hull is that a taxon (in particular a species) is a concrete
object, not an abstract one. Concrete objects are spatiotemporally restricted, or, to
put it another way, have an index space−time coordinate or range of coordinates.
Abstract objects do not have such an index.
Functional or cohesive individuals (“Systems”): These are objects which happen
to have some common systematic set of interactions (either temporal or formal). This
is the sense of “individual” that applies to a Mayrian biospecies—his notion of gene
flow as a homeostatic mechanism suggests that he thought of species as functional
units.
Phenomenal individuals (“Appearances”): These are objects which can be
observed in their entirety as entities. This is very often scale-dependent (a colony
can look unified at one scale and appear as a multiplicity of objects at a finer scale).
Now, this gives us a field of eight options: a putative taxonomic entity can be
one of those seen in Table 13.1. Shading in the table indicates the possible kinds
of classes (top) and individuals (bottom), with names for each option in italic. The
question is then what sort of entity/individual a species is (this can be different for
different species). Leaving out the metaphysically abstract species (A), which is what
Ghiselin and Hull do (but Ruse does not), working from Strawson’s Individuals^23 for
obvious reasons (as no individual organism would ever be a member of its species,
only a “realization” of it), and the appearance-based kinds (B–D) and we are left
with four options: a species is a historical entity without causal cohesion or phenom-
enality (E); a species is a historical entity with causal cohesion but no phenomenality
(F); a species is a historical individual with no causal cohesion but phenomenality
(G), and a species is all three (H). Option E fits any spatiotemporally delimited group
of organisms (including any lineage or clade); Option F and G fit Mayrian species
(the second being cryptic species), and Option E represents any “taxonomic” species
that lacks a mechanism as such for keeping it distinct.
Consequently, I can’t agree with the premise that to be a metaphysical individ-
ual requires causal cohesion or functional integration, as is sometimes expressed.^24
Paradigmatic individuals (i.e., organisms) do have this cohesiveness and are usually
phenomenally distinct, but this is not an argument that all metaphysical individuals
must be. A hive is functionally cohesive but sometimes not phenomenally distinct,
for example (of course, as phenomenal distinctiveness is scale-relative, a hive might

(^22) Zalta 1988.
(^23) Strawson 1964, Chapter 8.
(^24) For instance, by Ghiselin 1997. Gould 2002, 602–603, for example, offers four conditions for select-
able individuals: change, discreteness and cohesion, continuity, and functionality or organization.
He needs these for species to be subjected to species selection.