Abstract

What are species? In asking that question, one could be asking one of at least three distinct questions: What groups of organisms constitute species? What logical framework should one use in formulating and analyzing claims about species, specifically, claims about the evolutionary behavior of particular species? What conceptual framework should one use in formulating and analyzing claims about species, specifically, the claim that species have the capacity to evolve, that they are units of evolution? ;In response to question , I adopt an approach suggested by Mishler and Donoghue and Mishler and Brandon , namely, a pluralistic approach to the species category. In response to question , I argue that one can conceive of species as sets, that is, that one can adopt the logical framework of set theory to formulate claims about the evolution of particular species. Lastly, in response to question , I articulate a conception of species as groups of lineages and show how that conception is helpful in addressing several issues concerning the role of species in evolutionary biology