THE PLURALISTIC TENOR OF THE TIMES

As I noted at the outset of Part Four, the return of the group has focused the attention of philosophers and biologists on the relationships between various putative levels at which natural selection operates, particularly on those between group, organismal, and genic selection. Both unbridled enthusiasts and more circumspect critics of the form of group selection that has received most attention – that of David Sloan Wilson and Elliott Sober – have endorsed pluralism about the agents of selection. In fact, one or another form of pluralism about the agents of selection constitutes the current orthodoxy in the philosophy of biology. The two goals of this final chapter are to critically examine this pluralistic consensus, and to introduce an alternative to it, one that questions the adequacy of the underlying conception of natural selection as operating at distinct “levels.”

I begin in the next section by distinguishing several forms that such pluralism has taken, turning in sections 3 and 4 to elaborate on and then critique the most widely endorsed form of pluralism and the central argument given for it. Pluralism is motivated by the intuition that there may not be a determinate answer to the question of just which level is “the” level at which selection occurs in any particular case. In section 5, I shall spell out this intuition in a way that breaks from the pluralist consensus by developing the notion of entwined levels of selection that I introduced briefly at the end of the previous chapter.