I’ve generally been dubious about trolley problems and similar thought experiments in ethics. However, it’s just occurred to me that an idea I’ve tried to express in the economistic terms of opportunity cost, without convincing anybody, might be more persuasive as a trolley problem. So, let’s start with the standard problem where the train is about to kill ten people, but can be diverted onto a side track where it will kill only one.
In my version, however, there is a second train, loaded with vital medical supplies, which is about to crash. The loss of the supplies will lead to hundreds of deaths. You can prevent the crash, and save the supplies, by diverting the train to an alternative route (not killing anybody), but you don’t have time to deal with both trains. Do you divert the first train, the second train, or neither?
Hopefully, most respondents will choose the second train.
Now suppose that the first train has been hijacked by an evil gangster and his henchmen, who will be killed if you divert it, but will otherwise get away with the crime. As well as the gangsters, the single innocent person will die, but the ten people the gangster was going to kill will live.
The impending crash of the second train isn’t caused by anybody in particular. The region it serves is poor and no one paid for track maintenance. If the train doesn’t get through, hundreds of sick people will die, as sick poor people always have, and nobody much will notice.
Does that change your decision?
As I hope at least some readers will have realised, this version of the trolley problem is a metaphor for humanitarian military intervention. The moral intuition supporting such intervention is the same one that would lead to choose stopping the gangster over saving lives of people who would otherwise die as a result of poverty and disease.
As I’ll argue at length if needed, the numbers in the example are stacked in favor of humanitarian intervention. Many such interventions kill more people than they save. Even where they are successful in their own terms, the cost is massively more than that of civilian aid, for a fraction of the benefit.
One final point is that, in reality, the ‘henchmen’ are often conscripted, by force or economic necessity, from the same population as the people whose lives are supposed to be saved by intervention. On any reasonable account, their deaths ought to be weighed in the ledger against any lives saved.