Friday, April 17, 2015

Contra Reductionism in Biology



I just finished reading two excellent essays in Contemporary Debates in Philosophy of Biology.  The book, edited by Francisco J. Ayala and Robert Arp, consists of a series of duets: essays taking opposite positions on basic questions in that domain.  The first essay was by Evelyn Fox Keller, who I had the pleasure of meeting in the mid-nineties during a six week seminar at Dartmouth College, led by Roger Masters and Ron Perlman. 
Keller’s essay is entitled “It is Possible to Reduce Biological Explanations to Explanations in Chemistry and/or Physics”.  It is a very good introduction to the basic problem of reductionism in biology.  It is followed by an essay by John Dupré.  Dupré adds the word “not” to Keller’s title. 
It tells almost all that Keller begins by largely conceding the point.  She notes that in physics and chemistry, the fundamental principles are common denominators and they are coextensive, or equated, with the simple.  To provide my own example, the periodic table of the elements, so basic to chemistry, is literally a poster for simplicity.  By contrast, “whatever the meaning of fundamental in biology, it clearly cannot be equated with simple, nor is it at all obvious that it is common to all biological entities”.  Physical principles are simple and apply to everything in their domain.  Biological principles are rather few if any, and they are very complex.  The best of them admit to exceptions.  So how can we hope to reduce the one to the other? 
Keller goes on to do an admirable job of lubricating the track between the hard sciences of chemistry and physics and the flaccid science of biology by introducing a non-biological, simplified version of function.  In this view, if I understand it, a river functions as part of a system whereby water leaves the ocean for the sky, the sky for the mountains, and the mountains to get back to the sea.  The river is functional because “it contributes to the self-regulation of some entity of which it is a part.”  I note that she was quoting William Wimsatt here, who I also met in Dartmouth.  Pardon my name dropping, but this is taking me down memory lane. 
That simple version of function is fully compatible with physics.  However, while the river functions to get water down it doesn’t function to maintain some internal state of equilibrium (or more accurately, specified disequilibrium).  It doesn’t function to maintain a certain level of water or to keep the water within a specified range of temperatures.  That kind of function seems unique to living organisms, the organization of which functions precisely to keep the internal state within certain parameters by resisting and exploiting external conditions.  It occurs to me at this moment that this description of function neatly explains the difference between a virus, for example, which functions in the first sense, and its bacterial prey which functions in the second. 
As I suggested, the gap between the two kinds of function largely concedes the resolved point.  Chemistry and physics can explain the one kind of function but not the other. 
John Dupré makes the case against reductionism by arguing in favor of “strong emergence”.  He makes the distinction between the whole (a lynx, for example) and the parts (organs, cells, subcellular machinery, etc.).  He denies that “the behavior of the whole is fully determined by the behavior of, and interactions between, the parts.”  My own version of his argument goes like this: precisely because the organism works to maintain its own internal states from succumbing to equilibrium with its surroundings and does so by resisting and exploiting the conditions it finds itself in, its behavior is determined in part by those external conditions.  Those external conditions are determined not only by the physical nature of the molecular components but by a very wide range of accidents.  The same air can be bitterly cold or blisteringly hot.  At the very least, biology has to consider those accidents and among them is the accidental arrangement of molecules into living organisms. 
The unavoidable conclusion is that biology cannot be reduced to chemistry and physics.  Keller is at least open to the possibility that the one might be reduced to the other and suggests some avenues by which that possibility might be explored.  I do not think she succeeds in making it look likely. 
Since I am of the tribe of Plato and Aristotle, I am allergic to reductionism in all its forms.  So I am pretty happy with this outcome.  One thing that both authors profess to believe in, however, is materialism.  I am not a materialist.  Moreover, I don’t think that Keller or Dupré are either.  I intend to demonstrate that in the next post. 

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