The Relational Nature of Species Concepts :: Species Positivism Essays

The Relational Nature of Species Concepts ABSTRACT: Édouard Le Roy as early as 1901 observed the existence of an intellectual movement seeking to break from traditional positivism and set for himself the task of drawing up the program of this new positivism. Noting that this program precedes the Vienna Circle, I endeavor to determine its nature and to evaluate its impact on logical positivism. Viewed in this light, the discussions between Le Roy, Poincarà © and Duhem appear more prolonged and substantial than is usually thought. What we have here is perhaps not a homogeneous doctrine but a vigorous intellectual movement, from which logical positivists were able to borrow specific theses in their attempts to mitigate Mach's strict positivism; more important still, they had before them an example of neopositivism. History is not the only concern: among the issues debated, one encounters the claim that facts are theory-laden. This claim still stirs controversy today. An inquiry into the origins of the claim is one way of c larifying the arguments involved. The definition of the concept of a species has been a recurrent issue in evolutionary biology at least since the publication of The origin of species (Darwin, 1859). Despite numerous treatments (e.g., Ghiselin, 1974, 1987; Hull, 1976a, 1976b, 1978; Kitcher, 1984; Kitts, 1984; Kitts & Kitts, 1979; Mayr, 1957, 1963, 1976a, 1976b, 1987; Meglitsch, 1954; Mishler & Brandon, 1987; Mishler & Donoghue, 1982; Sober, 1984; Sokal, 1973; Sokal & Crovello, 1970; Wiley, 1978), the species problem still represents a conceptual issue. In the present paper, I submit that all species concepts are relational in nature. In its most general expression, this idea is not new. Indeed, according to Mayr (1976a), "the species concept is a relational concept" (p. 480). However, the interpretation and further elaboration I propose is different from Mayr's. The crucial difference is that I adopt the set-theoretic notion of a relation. A consequence of this adoption is that, in contrast to Mayr, who restricts his idea to the relation of reproductive isolation (which defines his own species concept), I argue that the set-theoretic notion of a relation allows us to define any species concept in terms of some kind of relation. A second consequence has to do with the rejection expressed by Mayr and others towards viewing species as sets. I shall have something to say about this issue at the end of the paper. The notion of a relation is central to scientific concepts in general, and the species concept is no exception.