Many physicians find the task even harder when a very old person declines over a few weeks or months and then dies. The steps of that process often include muscular weakness that leads to inactivity and increased susceptibility to infection, or poor intake of food and fluid that leads to dehydration and electrolyte imbalances in the blood and a final fatal heart rhythm. The "underlying cause" is hard to find even with an autopsy.There can be proximate causes, contributory causes, and interacting causes; sometimes one thing causes a chain of other things, but sometimes each of two (or more) causes are necessary for a death, and neither would have lead to the death by itself. I was thinking about this this past weekend, when several Bronx residents died of not wearing their seat belts. There were other causes as well, of course, but this seems to have been a necessary one.
This is a big issue in economics as well. Much of the housing boom involved people borrowing money that they could pay back, barely, if they got regular raises and never had a kid get sick or a car break down. Blaming a default in a situation like that on the car breaking down seems to be missing the cause that was more significant, or at least more reasonably susceptible to different behavior. And the same, naturally, applies to management plans that require that nothing go wrong.