A short historical overview of the debate on reductionism in biology

Zdenka Brzovic

University of Rijeka

This paper examines the development of the debate on the possibility of epistemic reductionism in biology and its relation to the question about the status of biology as an autonomous science. The debate on reductionism in biology started with the discussion of Ernest Nagel's (1961) model of reduction in the 1970s which assumes that to reduce a theory means to derive it from the reducing theory. Kenneth Schaffner (1967) adopted Nagel's account of theory reduction and introduced it to biology where the central issue of the debate was whether classical genetics can be reduced to molecular genetics. Schaffner's model of theory reduction motivated a large debate concerning the possibility of reduction in biology that ended up in the so-called ''anti-reductionist consensus'' since it seemed that theories in biology are not suitable for reduction into a theory about more basic phenomena. An important objection was that theory reduction assumes that theories in biology are sets of statements in formal language, which include observation statements, bridging principles and statements about general laws. However, biology does not contain laws in the strict sense so it follows that theoretical reduction is not possible. This problem and some other objections to the possibility of theoretical reduction in biology gave rise to the idea of explanatory reduction where reduction does not necessarily need to be a relation between theories; it can include fragments of a theory, generalizations, mechanisms etc. It is interesting to approach the debate on reductionism from the perspective of the views held on the status of biology as an autonomous science. On the one hand many authors perceived the failure of reduction of classical genetics to molecular biology as evidence that biology is an autonomous science that cannot be reduced to chemical or physical principles. However, on the other hand, one of the reasons why reduction was not accomplished was the fact that biology does not contain any strict laws; which was one of the arguments that, according to some, showed that biology is not a real scientific discipline after all. In this paper I examine how these 'external' factors (views on the status of biology as a science) affected the debate on reductionism. My aim is to show that connecting the two debates (the debate on reductionism and the debate on the status of biology as a science) was not always very productive since it distracted the authors from arguments on reductionsim by bringing to the foreground the issue of establishing biology as a proper, autonomous science. The present debate on the explanatory reductionism seems more productive since there seems to be a consensus that even if reductionism is true and we can in principle reduce all explanations in biology to explanations in molecular biology, this does not threat the status of biology as autonomous science since it is still pragmatically useful to keep higher level explanations.