114 Maarten Franssen
in the philosophy of science as to the explanatory value of such statements. For starters,
how do we know that a particular Hopi rain dance does not contribute to social cohesion?
Because there is a confl ict? There can be lots of reasons why rain dances can fail to give
rise to social cohesion, just as there are many reasons why an electric drill can fail to drill
a hole in the wall even though the drill itself is not malfunctioning.
Normative statements seem thus to be applied much more reticently than the functions
that they are supposed to be associated with are. In their turn, biological functions are
attributed much more reticently than the theories that are supposed to ground them would
allow. On the PF theory, for example, it is just as much a proper function of foxes to feed
on rabbits as it is the proper function of the stomachs of foxes to help digest bits of rabbit.
Individual foxes are the members of the higher-order reproductively established family of
all present and past foxes, which are produced by the members of the fi rst-order repro-
ductively established family of complete fox genomes, the proper function of which is to
produce fox phenotypes. And it is in terms of their habit of eating rabbits that the existence
of proliferation of foxes in nature is Normally (Millikan’s (1984) capitalization) explained.
If we are hesitant in applying the concept in this way, it is, I suggest, because we shrink
from the consequences with respect to our employment of normative language. If it is the
proper function of foxes to feast on rabbits, then a fox that has a distaste for rabbits is a
malfunctioning fox, which ought to eat rabbits, and one fox may be a poor fox compared
to another one. One may try to oppose this by saying that it is the proper function of foxes
to feed on whatever is available, rather than rabbits in particular. Still, the rabbit-eating
habit of foxes satisfi es the defi nition, or if not the rabbit-eating habit then surely the rodent-
eating habit or the smaller-mammal-and-bird-eating habit, to be somewhat more accurate.
What is more, there are enough examples where the feeding habits of a species are so
fi xed that on the PF theory the corresponding functions must be attributed to organisms,
and by an obvious extension to species.
The SE theory is explicitly phrased to attribute functions to the parts of organisms, at
least in Neander’s articulation. There is no good reason, however, why this should be read
as applying only to proper parts; that is why one cannot treat the organism itself as being
a limiting case of a part of it, just as any set is a member of the set of its subsets. But even
if the defi nition would be restricted—arbitrarily—to proper parts, then it seems possible
to extend the meaning of organism such that an organism in the ordinary sense is indeed
a proper part of an organism as technically defi ned. Flowers of the plant species Yucca
glauca feed moths of the species Tegeticula yuccasella (or rather their larvae), and they
do so because previous generations of yucca plants did, since the moths are essential to
fertilizing the yucca fl owers. The life of yucca and moth are so intertwined, in mutual
exclusiveness, that a single yucca can be considered as a proper part of a yucca-moth pair,
such that the feeding of previous moth larvae by previous yucca fl owers contributed to
the inclusive fi tness of the ancestors (other yucca-moth pairs) of this yucca-moth pair and
caused (in the sense of causally contributed to) the genome of such pairs (themselves