534 Tim Lewens
around the building site, and then cataloguing how various Newtonian forces act
on them so that they fall into their final resting places. However, this does not
explain in a satisfactory way why, when the bricks and window frames could have
come together into a useless pile, they did in fact form such an elegant dwelling.
Here we point to a rational plan that explains this ordering, and Kant is unable to
see how a mechanistic explanation of development could escape a similar charge of
contingency unless supplemented with appeal to some type of rational plan, too.
Darwin’s great breakthrough is to show, through natural selection, why organisms
come to be well ordered. Selection explanations show us how the fact that a trait
of a particular formwouldaugment an organism’s reproductive fitness, can bring
about the existence of a trait with just such a form. The creativity of natural
selection is an important factor in undermining Kant’s worry that mechanical
explanations will always leave contingent the adaptedness of organic form.
4 PROBLEMS WITH THE SELECTED EFFECTS ACCOUNTThe SE account has generated a very large literature in recent years, and there is no
sense in trying to survey every objection that has been raised here ([Buller, 1999b]
and [Allenet al., 1998] are comprehensive collections of important recent articles).
Most objections turn on two features of the theory, both of which yield somewhat
quirky results. First, the SE account is backward-looking. Traits have functions
in virtue of their selection history, and for this reason the SE account is sometimes
called anetiologicalaccount. Second, the account is highly theory-laden. Biolog-
ical functions are analysed in the technical terms of modern evolutionary theory.
The first feature commits the SE account to the following two pronouncements:
A: A new mutation — let’s say a pair of fully functional eyes, which
enhances fitness greatly — arises in a population. Organisms with eyes
increase in frequency in the population. Consider the first generation
after the original eyes arise. It is, strictly speaking, a mistake to say
that there are lots of organisms with eyes in this generation because
earlier eyes had the function of assisting in vision. The earlier eyes had
no functions at all, for they had no history of selection.
B: An atom-for-atom replica of a lion, which coalesces one day from a
chance coming-together of molecules, has no organ for pumping blood
even though it has an organ that does all the same things as a normal
lion’s heart. With no evolutionary history, no parts of this lottery lion
have any functions.The second feature commits the SE theorist instead to a third type of claim:C: It appears that Harvey correctly identified the function of the heart
as that of pumping blood. But Harvey cannot, in fact, have known the
correct biological function of the heart, for Harvey (pre-dating Darwin