 Rachel Cooper (2007) presents a way of thinking about psychiatric explanation that fits well with the idea that a diagnosis lets us tell a story. We often find ourselves with narratives that tell us how someone gets sick, and it might be that a useful narrative is one which isolates the temporally prior variables and lets us see how later phenomena depend on them. One way to think about this is that a good narrative is one that talks about a natural kind. If we have a natural kind, with some causal structure underpinning it, the systematic dependence of later states on earlier ones is easy to grasp. Several theorists have defended a view of psychiatric disorders as natural kinds. Influential recent philosophical treatments have rejected the idea that mental disorders have essences, but have defended the idea that mental disorder are natural kinds in Boyd’s sense of homeostatic property clusters (Beebee and Sabbarton-Leary 2010; Kendler et al. 2010; Parnas et al. 2010; Samuels 2009, Zachar 2014, Pereira 2020), in which properties occur together often enough, and reliably enough, to support ampliative inferences, even if the mechanisms responsible for the kind do not make every member of it the same as every other member. When inductive reasoning works, thinks Boyd, it works because we have have latched onto these underlying causal mechanisms that bring about the clustering. Successful inductions track the observable manifestations of the causal mechanisms responsible for the characteristics of the kind. The mechanisms, we might say, leave an identifiable causal signature in the world.  The HPC account seems to suit mental disorders. They often vary across cases, with characteristic symptoms sometimes absent even when the patient presents a typical cluster of signs and symptoms. So it is understandable that theorists who are sympathetic to the medical model in psychiatry should be drawn to the homeostatic property cluster idea.  