In his "Discussion" (1984), Elliott Sober offers some criticisms of the view about species--pluralistic realism--advocated in my 1984. Sober's comments divide into three parts. He attempts to show that species are not sets; he responds to my critique of David Hull's thesis that species are individuals; and he offers some arguments for the claim that species are "chunks of the genealogical nexus." I consider each of these objections in turn, arguing that each of them fails. I attempt to use Sober's (...) insightful critique to explain and defend pluralistic realism more fully. (shrink)

One possible interpretation of the species concept is that specifies are natural kinds. Another species concept is that species are individuals whose parts are organisms. Philip Kitcher takes seriously both these ideas; he sees a role for the genealogical/historical conception and also for the one that is “purely qualitative”. I criticize his ideas here. I see the genealogical conception at work in biological discussion of species and it is presupposed by an active and inventive research program, but the natural kind (...) concept is not. I also criticize Kitcher’s criticisms against Hull’s position that species are individuals, including Kitcher’s idea that species are sets of organisms, his explanations of why “all swans are white” isn’t law-like, his discussion of the example of multiple origination. Finally, I argue that given the current evolutionary developments, pluralism is the "null hypothesis" that we should attempt to refute. (shrink)

Although it is possible to regard a species as a set with a special internal structure, it is preferable to regard a species as an individual precisely to emphasize this internal structure. It is necessary to recognize, moreover, that two organisms that are part of a single entity with respect to one process need not be part of a single entity with respect to another process. Furthermore, choosing to regard two entities (with respect to one process) as conspecific is not (...) to deny that there are two entities within this species. Thus, the systematist need not propose formal names for every entity he discovers, but the names he proposes ought to be as faithful to the relationship among the entities as is possible. (shrink)