 Advocates of representationalist approaches to immune cognition accept the subject-object dichotomy that portrays the immune system as a “knower”, an agent, who can represent the state of its inner and other environments (Tauber 2013). This has become a well-entrenched orientation inasmuch as the ontological understanding of key concepts in immunology—self, individuality, and organism—revolves around the status of agency in immune theorizing. As already mentioned, from the very inception of the discipline, immunologists have either assumed an implicit identity that grounds the distinction between self and foreign, or that identity is explicitly described as an agent at the heart of immune defense. Traditionally associated with the capacity of an intentional, conscious being to act (see the entry on  agency),  agency has been redefined in philosophy of immunology to refer to the source of immune activity.