Reductionism in Biology 359Biology is unavoidably terrestrial. Its explanatory resources are spatiotempo-
rally restricted in their meanings. Thus, the debate between reductionism and
antireductionism will have to be one about the explanation of particular historical
facts, some obtaining for longer than others, but all of them ultimately the contin-
gent results of general laws of natural selection operating on boundary conditions.
Reductionism needs to claim that the most complete, correct, and adequate ex-
planations of historical facts uncovered in functional biology is by appeal to other
historical facts uncovered in molecular biology, plus some laws that operate at the
level of molecular biology. Antireductionism must claim that there are at least
some explanations in functional biology which cannot be completed, corrected, or
otherwise improved by adducing wholly nonfunctional considerations from molec-
ular biology. One way to do this would be show that there are some functional
biological phenomena that cannot in principle be decomposed or analyzed into
component molecular processes. But such a demonstration would threaten the
antireductionist’s commitment to physicalism. A more powerful argument for
antireductionism would be one which shows that even in macromolecular explana-
tions, there is an unavoidable commitment to ultimate explanation by (implicit)
appeal irreducible functional — i.e. evolutionary laws, such as the PNS.
Reductionists can provide a strong argument for their view and rebut antireduc-
tionist counterargument effectively. But to do so they need to show that ultimate
explanations in functional biology are unavoidably inadequate, and inadequate in
ways that can only be improved by proximate explanations from molecular biology.
This would indeed refute antireductionism. Or it would do so if the reductionist
can show that these proximate explanations are not just disguised ultimate expla-
nations themselves. It is the literal truth of Dobzhanky’s dictum that of course
will make one suspicious that this cannot be done. What the reductionist must
ultimately argue is that the laws of natural selection to which even their most
macromolecular explanations implicitly advert, are reducible to laws of physical
science. This second challenge is the gravest one reductionism faces. For if at the
basement level of molecular biology there is to be found a general law not reducible
to laws of physics and chemistry, then antireductionism will be vindicated at the
very core of the reductionist’s favored subdiscipline.
Let us consider the first challenge, that of showing what makes ultimate ex-
planations in functional biology inadequate in ways only proximate molecular ex-
planations can correct. Recall Mayr’s [1981] distinction between proximate and
ultimate explanation. Consider the question of why butterflies have eye-spots on
their wings. This question may express a request for an adaptationist explanation
that accords a function, in camouflage for instance, to the eye-spot on butter-
fly wings, or it may be the request for an explanation of why at a certain point
in development eye-spots appear on individual butterfly wings and remain there
throughout their individual lives. Reductionism in biology turns out to be the
radical thesis that ultimate explanations must give way to proximate ones and
that these latter will be molecular explanations.
To expound this thesis about explanations, reductionism adduces another dis-