Philosophy of Biology

Reductionism in Biology 353

The unavoidable conclusion is that as far as the post-positivist or “layer-cake”
model of intertheoretical reduction is concerned, none of its characteristic pre-
conditions are to be found in theories of functional biology, theories of molecular
biology, or for that matter in any future correction of one or the other of these
theories.

2 INTERTHEORETICAL ANTIREDUCTIONISM

If antireductionism were merely the denial that post-positivist reduction obtains
among theories in biology, it would be obviously true. But recall, antireductionism
is not merely a negative claim. It is the thesis that

a) there are generalizations at the level of functional biology,

b) these generalizations are explanatory,

c) there are no further generalizations outside of functional biology which ex-

plain the generalizations of functional biology,

d) there are no further generalizations outside functional biology which explain

better, more completely, or more fully, what the generalizations of functional

biology explain.

All four components of antireductionism are daunted by at least some of the
same problems that vex reductionism: the lack of laws in functional biology and
the problems facing an account of explanation in terms of derivation from laws.
If there are no laws and/or explanation is not a matter of subsumption, then an-
tireductionism is false too. But besides the false presuppositions antireductionism
may share with reductionism, it has distinct problems of its own. Indeed, these
problems stem from the very core of the antireductionist’s argument, the appeal
to ultimate explanations under written by the theory of natural selection.
To see the distinctive problems that an appeal to the ultimate/proximate dis-
tinction raises for biology’s autonomy, consider a paradigm of putative irreducible
functional explanation advanced by antireductionists. Our example is due to one
of the most influential of antireductionist physicalists, Philip Kitcher. It is one
that has gone largely unchallenged in the almost two decades between the first
and the latest occasion in which it has been invoked in his rejection of reduc-
tionism. The example is the biologist’s explanation of independent assortment of
functional genes. The explanadum is:

(G) Genes on different chromosomes, or sufficiently far apart on the same
chromosome, assort independently.

According to Kitcher, the functional biologist proffers an explanans for (G),
which we shall call (PS):