Life in a Physical World : The Place of the Life Sciences

Abstract

Debate about the place of the life sciences within the empirical sciences has often centered around the issues of physicalism and reductionism.1 Given that some form of physicalism is correct, why is biological science not physical science? Why do biological theories appear to be autonomous and irreducible to physical theories? And what is the nature of biological laws or regularities, assuming that the fundamental interactions that govern the physical world also are at work in living organisms? These are some of the oldest and most extensively discussed questions concerning the biological sciences. While philosophers of science of a Logical Empiricist bent first tried to defend the view that biological theories such as those of classical Mendelian genetics are in principle reducible to physical- chemical theories,2 an anti-reductionist consensus emerged during the 1970s.3 This consensus was mainly based on the argument that genetic concepts such as dominance or the gene concept itself cannot be redefined in an extensionally equivalent way in terms of molecular concepts. The reason for this is thought to lie in the functional character of biological concepts. This means that certain theoretically significant properties in biology are individuated by their causal role, not some intrinsic structural property. But the molecular realizers of these causal roles are highly heterogeneous at the molecular level; in others words, the realizers don’t have a theoretically significant molecular property in common that could be used to eliminate the higher-level terms. Therefore, higher-level concepts in biology remain explanatorily indispensable; they have autonomous explanatory value that cannot be reproduced by molecular theories alone.