Reconstituted Chicken

Philip Kitcher

  • This is Biology by Ernst Mayr
    Harvard, 340 pp, £19.95, April 1997, ISBN 0 674 88468 X

Ernst Mayr is one of the century’s pre-eminent Darwinian evolutionists, who, in the past two decades, has published a magisterial history of biology and many seminal philosophical essays. From the title of this new book, one might expect a tour of the current state of the life sciences, made accessible to non-specialists. His selection of topics, and his way of writing about them, suggest, however, that he is less interested in communicating substantive pieces of biology than in cultivating a particular way of seeing the subject – an attitude that would appear to derive from a pre-occupation with the ideas and controversies of the past. Specifically, Mayr wants to oppose the view that biology is a science inferior to physics, to campaign for philosophical and historical approaches to the sciences that do not see all science in the image of physics, to advertise the vitality of particular branches of biology, and to defend the view that the sciences can be understood in terms of reason and progress.

On all these points, Mayr seems substantially correct. But in some chapters, he expends much effort to quash attitudes that are no longer popular; in others, he writes as if a view needs only to be stated for his readers to be convinced of its rightness. The book thus has an air of exorcising old ghosts and, in waging his campaign against them, Mayr neglects some of the most exciting aspects of today’s biology.

A central theme of the early chapters is that ‘biology is, like physics and chemistry, a science. But biology is not a science like physics and chemistry; it is rather an autonomous science on a par with the equally autonomous physical sciences.’ Since biology has been the glamour science of the last decades, few people are likely to quarrel with the first part of this, but, as Mayr is well aware, the difficulty has to do with biology’s autonomy. The enormous successes of molecular biology invite the thought that we have transcended the old idea of biology as glorified tadpole-gathering precisely because biologists have begun to deploy the concepts, principles and techniques of physics and chemistry: because, properly understood, biology is reducible to physics and chemistry.

Nobody who wants to resist reductionism believes that, besides vast numbers of molecules, living things contain some special stuff: vitalism is dead. Yet many biologists, Mayr included, have reservations about the strategy of approaching all biological questions by first asking what the ultimate molecular constituents are and how they are fitted together. Ardent champions of molecular biology, inspired by its indisputable triumphs, often see this as a residual fuzzy-mindedness that expresses itself in nostalgia for ‘whole organism’ biology. The challenge for their antireductionist adversaries is to explain how it is possible to accede to the commonplace that organisms are physico-chemical systems while rejecting the idea that biological explanation is a matter of grinding out the chemical details.

Mayr attempts to meet this challenge by defending a view he calls ‘organicism’. He introduces this by contrasting it with the reductionism he rejects: ‘The basis of organicism is the fact that living beings have organisation. They are not just piles of characters or molecules, because their function depends entirely on their organisation, their mutual interrelations, interactions, and interdependencies’. Who would disagree? Every molecular chauvinist admits that the ways in which the constituent molecules of a living system are organised are crucial. One can’t refute reductionism by the macabre argument (which I once heard offered by a professor of biology) that if a chicken is puréed in a blender you have all the same molecules but no chicken. Nor can one pick out a distinctive position by Mayr’s more tasteful celebration of organisation.

Organicism holds that some of the properties of the living system are ‘emergent’, i.e. in Mayr’s phrase, they ‘could not have been predicted from a knowledge of the lower-level components’. Everything turns here on what we take the ‘knowledge of the lower-level components’ to consist in. If we just mean ‘knowledge of the constituent molecules but not of their organisation’, then certainly living things have emergent properties, but this is irrelevant to the reductionist programme, for real-life reductionists are clear from the start that the organisation of the constituents matters. If, on the other hand, we suppose that the ‘knowledge’ includes a complete understanding of the relations among the constituents, then the claim that living systems have emergent properties needs explanation and defence.

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