  In particular, natural history explanations fit a conception of diseases as syndromes unfolding over time that is enshrined in both DSM-IV-TR and the minimal construal of the medical model. It does not deny that there are causal processes, but sees mental illnesses as collections of signs and symptoms with characteristic histories. They doubtless depend on physical processes but are not defined or classified in physical terms. This picture of disease naturally goes along with the employment of natural history explanations, since they too invoke natural kinds without worrying about the mechanisms that explain the behaviour of members of the kind. It’s enough to be able to identify kind membership, thereby giving us a degree of explanatory and predictive control.