Leiter and Weisberg: Nagel opposes two main components of the “materialist” view inspired by Darwin’s theory of evolution by natural selection. The first is what we will call theoretical reductionism, the view that there is an order of priority among the sciences, with all theories ultimately derivable from physics and all phenomena ultimately explicable in physical terms. We believe, along with most philosophers, that Nagel is right to reject theoretical reductionism, because the sciences have not progressed in a way consistent with it. We have not witnessed the reduction of psychology to biology, biology to chemistry, and chemistry to physics, but rather the proliferation of fields like neuroscience and evolutionary biology that explain psychological and biological phenomena in terms unrecognizable by physics. As the philosopher of biology Philip Kitcher pointed out some thirty years ago, even classical genetics has not been fully reduced to molecular genetics, and that reduction would have been wholly within one field. We simply do not see any serious attempts to reduce all the “higher” sciences to the laws of physics.
Coyne: Here all three academics (Weisberg is a philosopher; Leiter a professor of law) make a mistake: the view that all sciences are in principle reducible to the laws of physics, which is materialism, is not identical to an attempt to reduce all sciences to physics. The former must be true unless you’re religious, while the latter is a tactical problem that will be solved to some degree as we understand more about physics and biology, but is unlikely in our lifetime to give a complete explanation for higher-level phenomena. Remember, though, that “emergent phenomena” must be consistent with the laws of physics, even those laws may not be useful for explaining things like natural selection.
VR: Thanks, Jerry, for attacking nonreductive materialism, which is the strongest form of materialism.