  In effect we have a set of exception-prone generalizations about the pathways a disorder takes: people in this situation are likely to become depressed unless such and such intervenes. And when they are depressed they will probably have the following experiences, unless they have these other ones. Thagard’s idea of a narrative is helpful here; path models represent typical stories about characteristic ways of getting sick. But a narrative by itself might not explain anything; if it is explanatory, it is because earlier events mentioned in the narrative pick out the causes of later events.