 Furthermore, the concept of disease that is currently employed in most areas of medicine has undergone a process of development. For much of the modern era there has been a dialectic between two concepts of disease. On the one hand, there has been the idea that a disease is just an observable suite of symptoms with a predictable course unfolding. This notion dates back to Sydenham in the late seventeenth century. Kraepelin applied it to psychiatry as the basis for differential diagnosis, for example between subtypes of what was later called schizophrenia (1899, 173–175). The approach was supplanted as medicine matured by the concept of diseases as destructive processes in bodily organs which “divert part of the substance of the individual from the actions which are natural to the species to another kind of action” (Snow 1853, 155; for discussion see Whitbeck 1977, Carter 2003, Broome 2006). This is perhaps still the core medical conception of disease. It seeks explanations that cite pathological processes in bodily systems. More recent medicine has tended to weaken this slightly by adopting what Green (2007, ch, 2) calls an ‘actuarial’ model of disease. This model takes the presence of elevated risk, for example as indicated by high blood pressure, to be a disease even in the absence of overt symptoms or a clearly destructive pathological process (see also Plutynski 2018, ch. 2).