Invited Papers: The Significance of EvolutionAuthor(s): Philip KitcherSource: Noûs, Vol. 19, No. 1, 1985 A. P. A. Western Division Meetings (Mar., 1985), pp. 65-66Published by: WileyStable URL: http://www.jstor.org/stable/2215118 .

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INVITED PAPERS

The Sign ficance of Evolution PHILIP KITCHER

UNIVERSITY OF MINNESOTA

In recent years, many biologists have argued that the theory of evolu- tion by natural selection, the contemporary version of the theory originally advanced by Darwin, has great philosophical significance. I shall argue that they are half right.

Evolutionary theory is viewed as important both because it challenges prevailing philosophical conceptions of the structure of scientific theories and of the ways in which such theories are tested and confirmed. It is also taken to have important implications for our views about human behavior, human social institutions, human freedom, and human values. Hence, there is a thesis of methodological significance and a thesis of substantive significance. I claim that the former is correct and the latter faulty. Moreover, I suggest that providing a convincing philosophical account of the structure of evolutionary theory enables us to see clearly what is wrong with the controver- sial claims about human nature that are allegedly grounded in evolu- tionary theory.

On the approach I favor, Darwin's principal achievement con- sisted not in his discovery of any novel, general principles, but in his recognition of the significance of generalizations that had long been appreciated. Darwin proposed a general strategy for the ex- planation of a variety of biological phenomena, including the phenomena of apparent adaptations. His successors have not only applied this strategy to numerous examples. They have also refined the theoretical techniques for making such applications, first with the development of modern theoretical population genetics, more recently with the articulation of the concepts of inclusive fitness (Hamilton), evolutionary stable strategy (Maynard Smith), and of evolutionary optimization (numerous people).

Several of the novel ideas enable contemporary evolutionary theorists to explain the possibility of maintaining under selection behavioral characteristics whose evolutionary origin and persistence had previously appeared puzzling. As a result, various sociobiological programs have emerged, some of which are dedicated to the idea of reconstructing the evolutionary history of behavioral traits in

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groups that include Homo sapiens and drawing conclusions about human nature. It should not be concluded that these programs have achieved any new general evolutionary principles, that there is some new general theory of animal social behaivor which only the senti- mental fail to "apply" to our own species. Contemporary evolu- tionary theory retains the character of earlier versions of the subject: there is a set of approved techniques for constructing evolutionary explanations, and a collection of actual accounts; the latter must be judged on their individual merits.

The crucial first question to ask about the substantive thesis is whether the evolutionary explanations that underwrite the controver- sial claims about human nature satisfy the canons of confirmation that are applied in the rest of evolutionary theory. (This is only the first question, because linking evolutionary explanations to claims about human nature involves assumptions that deserve careful scrutiny). I claim that they do not. The best studies of the social behavior of groups of nonhuman animals are marked by attention to observational detail and consideration of theoretical alternatives that are quite absent in the discussions of groups that include humans.

I illustrate the point by considering two examples. The first is the well-known sociobiological thesis that men are, by nature, hasty and fickle, while women are faithful and coy. The second is Richard Alexander's attempt to explain the persistence of social systems in which men provide for the children of a sister. I shall attempt to show how both examples fall short of the standards that evolutionary biologists rightly set for themselves.

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