ABSTRACT During the past thirty years, immunological metaphors, motifs, and models have come to shape much social theory and philosophy. Immunology, so it seems, often has served to naturalize claims about self, identity, and sovereignty—perhaps most prominently in Jacques Derrida's later studies. Yet the immunological science that functions as “nature” in these social and philosophical arguments is derived from interwar and Cold War social theory and philosophy. Theoretical immunologists and social theorists knowingly participated in a common culture. Thus the “naturalistic (...) fallacy” in this case might be reframed as an error of categorization: its conditions of possibility would require ceaseless effort to purify and separate out the categories of nature and culture. The problem—inasmuch as there is a problem—therefore is not so much the making of an appeal to nature as assuming privileged access to an independent, sovereign category called “nature.”. (shrink)