Abstract

Most discussion of the unity of science has concerned what might be called vertical relations between theories: the reducibility of biology to chemistry, or chemistry to physics, and so on. In this paper I shall be concerned rather with horizontal relations, that is to say, with theories of different kinds that deal with objects at the same structural level. Whereas the former, vertical, conception of unity through reduction has come under a good deal of criticism recently (see, e.g., Dupré 1993), horizontal unity has generally been conceded to be an important goal. The most pressing questions about horizontal unification arise in the study of human behavior. Numerous sciences including psychology, economics, anthropology, sociology, and parts of biology, attempt to provide explanations of human behavior. It is possible that some of these sciences may be able to coexist peacefully or even cooperatively. However things do not always go so smoothly, and at least two approaches to human behavior, those deriving from economics and evolutionary biology, often involve clearly imperialist tendencies. Devotees of these approaches are inclined to claim that they are in possession not just of one useful perspective on human behavior, but of the key that will open doors to the understanding of ever wider areas of human behavior. In this paper I shall consider some areas in which economic and evolutionary imperialists are currently staking claims. It is of particular interest to look at situations where two the two imperialist programs are staking the same claim, but limitations of space force me to focus here mainly on economics, and my remarks on evolutionary imperialism will be cursory. As well as some specific insights into the particular strategies of these scientific programs, I hope that my discussion will throw some more general light on the limits of such general theoretical strategies and, thereby, I shall suggest some motivations for adhering to a horizontal pluralism of science that matches the vertical pluralism advocated by anti-reductionists.