Annals of the History and Philosophy of Biology

Holism, Coherence and the Dispositional Concept of Functions
consists in a capacity's contribution to another capacity. The exemplary case is the heart's
contribution to the circulatory system's capacity to transport solutes and cells through
the body. It is obvious that this basic relation differs from the basic relation in coherence
theories of knowledge. There, the basic relation is usually thought to be an inferential relation,
including deductive and inductive inferences (such as inference to the best explanation).
But I see no reason why the contributory relation between capacities that is under
discussion here should not be able to generate a coherent system as well. For example, it
is no obstacle that the basic contributory relation is asymmetrical. Most inferential relations
are also asymmetrical, and in particular those that are thought to be involved in
generating knowledge.
Having specified the relevant basic relation for coherence, we can spell out whence
coherence consists in. Let us say that a system of capacities is coherent if it contains a
sufficiently complex net of such contributory relations between the various capacities,
such that many capacities contribute to other capacities that contribute themselves to
other capacities and so forth. By contrast, an incoherent system would be one where
most of its capacities do not stand in such a network. 2 As an example, we may consider a
heap of sand. Its parts – the sand grains – have various chemical and physical capacities,
but these do not contribute to other capacities that are instantiated within the sand heap,
which themselves contribute to other capacities, and so on. All they do is to exert some
repulsive and frictional forces that keep the sand heap stable. This is not a sufficiently
complex web of capacities; hence, a sand heap is not a functionally organized system. 3
By contrast, biological organisms contain an elaborate network of capacities that contribute
to other capacities. Here is just a small section through such a network: The function
of certain ion channels in nervous membranes is to regulate ion permeability because
this capacity is part of an account of the nervous membrane's capacity to fire action
potentials. But the nervous membrane's capacity to fire action potentials is part of
an account of the nervous system's capacity to process information. Therefore, it is a
function of nervous membranes to fire action potentials. Furthermore, the nervous system's
capacity to process information is part of an analytic account of the organism's
2 In epistemology, a coherent system also needs to be self-consistent in addition to containing a sufficient number
of inferential relations. There is no equivalent for this condition in the present use of the concept of
coherence (capacities are not the sorts of things that can contradict each other), but none is required. Coherence
in general is about how things hang together or dovetail with each other. Note also that consistency is a
much weaker relation than coherence; a system of beliefs can be fully consistent yet lack coherence because
there are no or not enough inferential relations.
3 This account raises the question of where the border is between functionally organized systems and systems
that are not so organized. However, there doesn’t have to be a sharp border. I do not shy from the
possibility of “functionally organized” being a vague predicate. After all, being alive could be a vague predicate
just like being bald. As for artificial systems with a functional organization such as a car or a TV set, its
functions are parasitic on the engineer's intentions. Therefore, human artifacts are an entirely different issue.
For something to have biological functions it must be a self-reproducing system, that is, it must be able to
continuously replace its parts and maintain a stable state under a variety of external conditions. I take it that
this condition means that, in order to have biological functions, a system needs a certain complexity. Of
course, nothing in principle prevents human artifacts from becoming self-reproducing some day, in which
case they would become candidates for function ascriptions in the same sense as in biology.
Annals of the History and Philosophy of Biology, Vol. 10 (2005)
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