"Teleofunctions and Oncomice"
The view that organisms deserve moral respect because they have their
own purposes is often grounded in a specification of the biological
functions that the organism has. One way to identify such functions
is to determine the etiology of some behavior based on the evolution
of the structures enabling it. This view suffers from some
unacceptable problems, including that some organisms with profound
defects will by definition have a welfare interest in their defects.
For example, the patented oncomice, intentionally engineered and bred
for a genetic defect that leads to extremely high incidence of cancer,
would have a welfare interest in the development of tumors. The
systems-based theory of biological functions, which refers not to the
evolution of structures but rather their role in the organism, escapes
these problems, and shows how a theory of an organism's welfare
interest in its purposes can be grounded in a sound naturalistic
approach. This approach also has some fruitful corollaries, including
an elegant theory of why species may require special moral regard.
Environmental Ethics, Summer Vol. 26: 171-188.