How Biological, Cultural, and Intended Functions Combine 59
A functional assertion, however, indicates more than just the existence of a causal rela-
tion; it gives us information about its nature. It tells us not only that fact number 1 (the
easy digestibility of CFR corn) is the cause of fact number 2 (the large presence of CFR
corn in cultivated land) but also that this causal connection is neither a fortuitous one nor
simply a consequence of basic physical facts, that is an effect that could be drawn from
the laws of physics. It tells us also that this causal relation is a stable relation that results
from a persistent structure or mechanism. Thus by being told that the function of X is F,
we are told that the lasting presence (or the large diffusion) of X-bearers depends system-
atically, because of some general mechanism, on the fact that some or most X-bearers
have effect F, and that without such a mechanism the situation would in all likelihood be
quite different since physical laws and conditions cannot account for the lasting presence
(or the large diffusion) of X-bearers. However, the issue as to whether the stability of this
causal connection is due to something biological, cultural, or intentional remains out of
the picture. The nature of mechanism which may explain this causal connection is not
specifi ed. So, the pieces of information that a functional assertion delivers are substantial
but of a very abstract nature.
In the case of cultivated or domesticated species, the causal stability underlying bioar-
tifactual functions is in fact the result of very complex series of phenomena and mecha-
nisms acting at different levels: how human preferences and human knowledge transform
natural selection in artifi cial selection, how cultural mechanisms of various types diffuse
and speed up artifi cial selection, how plants and animals exploit the new environmental
conditions created by humans, and so forth. It seems to me that the whole thing could be
seen as a complex mechanism involving both biological and cultural parts. How such a
complex mechanism produces its output (in the case of our example, the fact that most
cultivated wheat produce CFR corn) from its input (the easy digestibility of CFR corn plus
a series of cultural and biological conditions) can be understood only if one retains a certain
level of generality. No satisfactory causal explanation can be obtained if the data are not
made to fi t into the general frame of a mechanism. Moreover, a very limited amount of
information will often be suffi cient to determine the general structure of such a mechanism,
thus satisfying our quest for an explanation. More information will often just help to fi ll
in the structure.
Let us take again our invented CFR corn example. A single piece of information, such
as “humans have always found CFR corn more palatable” or “tribes eating CFR corn suf-
fered less from malnutrition than neighboring tribes” is suffi cient to fi gure in rough outline
the general mechanism that may explain the diffusion or maintenance of CFR corn in some
area. Depending on the theoretical background, the mechanism sketched may be somewhat
different. For example, those who see in food preferences unexplained data will certainly
imagine a mechanism more superfi cial and with a more limited scope than those who see
in food preferences the result of a mechanism designed by natural selection to make us
favor what is more nutritious for us. However, and this deserves to be noted, no serious