The problem lies not so much even with the use of a reductionist methodology in medical science as with the ideology that holds that reductionism is the only legitimate scientific methodology. That leave no room for methodologies based on an emergent holism or upon dialectics. To some extent differences in opinion on this issue among scientists within biology in part seem related to the particular subdiscipline of the scientist. Thus many of the leading molecular biologists (i.e. James Watson) are very ardent reductionists (and indeed it is indisputable that reductionism has enjoyed some spectacular triumphs in moelcular biology, however, it does not follow that it it the only legitimate scientific methodology or even the one most appropriate for all areas of research). On the other hand the paleontologist, Stephen Jay Gould is an advocate of an emergent holism. Lewontin stands out from his fellow geneticists by being a critic of reductionist ideology and an advocate of a dialectical approach to biology.
Which makes an excellent case for an irreducible methodological pluralism. The dialectical approach works best at the organism/environment interface; reductionism works best at the molecular scale and anarchic pluralism works on the ecosystem scale. Emergent holism would seem to be more an ontological narrative than anything else [see Emergence: Non-Deducibility or Downwards Causation? by Jurgen Schroeder; The Philosophical Quarterly 48:193, 10/98]
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