A medical term which has gained currency in contemporary critical theory, especially in the work of Derrida, Jacques and Roberto Esposito, that refers to the paradoxical fact that human and non-human bodies are capable of perceiving a part of themselves as an âenemyâ requiring an immunity response. A body suffering from an autoimmune disease---such as multiple sclerosis---literally attacks itself: one part of the body (i.e. the so-called immune system) tries to kill another part of the body, as though it somehow did not belong there or was some kind of foreign invader. Autoimmunity is in this sense a form of self-defence that has gone wrong. Writing in response to the events of September 11, 2001, Derrida used this concept to expose one of the central paradoxes of the modern state, namely its capacity---we might also say willingness---to destroy one part of itself in order to save itself. To do so, it represents that which is inside the state as being something that really is from the outside, or at least ought to be relocated there. An obvious instance of this would be the treatment of refugees and asylum seekers, who, no matter whose border they cross, are always treated as outsiders. The fear generated in response to the presence of refugees and asylum seekers is, as Esposito argues, precisely an immune response. But a better analogy would be to think of the way elected government officials (parliamentarians, senators, and so on) speak of government (by which they mean government bureaucracy) as being the key problem they have to deal with. In this situation government treats itself as an âotherâ and attacks itself in order to preserve itself. Derridaâs point is that we cannot fully understand the self if we do not take into account its constitutive capacity for self-harm. But more importantly it means we cannot fully understand the state, including the democratic state, if we do not take into account its willingness to sacrifice a part of itself for the good of the whole. See also bare life; part who have no part. Further Reading: G Borradori (ed) Philosophy in a Time of Terror: Dialogues with JĂŒrgen Habermas and Jacques Derrida (2003).