Daniel Innerarity’s Ethics of Hospitality highlights a tension in both communities and individuals between embracing difference and protecting identity, while recognizing that difference is constitutive of identity (the fear that dominates contemporary society is above all a fear of difference, of contamination). This dynamical relation between difference and identity can be seen in the workings of the human immune system, as explained by Chilean biologist and philosopher Francisco Varela: the immune system is a process of perpetual construction of bodily identity through self-referential cognition and distinction between self and non-self. This similarity allows for interesting analogies: for example, a society torn apart by xenophobia and chauvinism can be seen as analogous to a body ravaged by an autoimmune disease such as lupus. With the working hypothesis that the similarities respond to what Stafford Beer calls “systemic invariance”, this paper explores the similarities between the activity of the immune system and the relation between identity and difference in the work of Innerarity.