The conceptual history of schizophrenia is marked by considerable dissent about its nosological status, and the question of whether it represents a distinct disease entity remains hotly debated. Another recurring feature in the conceptual history of schizophrenia is the reference to concepts of self and person. This paper brings in connection these two debates by interrogating the nosological function of “self” and “person” by means of a fictitious dialogue between Eugen Bleuler, the inventor of schizophrenia, and his contemporary Arthur Kronfeld. Introducing their respective accounts of schizophrenia with a special focus on how concepts of self and person figure therein, our analysis suggests that these concepts are primarily employed in an attempt to guarantee the nosological unity of schizophrenia: mediated by the concept of a core disturbance, alterations of the self or the person thus become the essential core of schizophrenia. Yet, rather than providing an easy solution to the nosological problem of the unity of schizophrenia, the concepts of self and person and their assumed disturbances are themselves fraught with debates about unity. We discuss these conceptual challenges in light of present-day nosological debates and the currently abounding research on the self.