The Trolley Problem is a thought experiment in ethics that can easily start an argument. The original form goes something like this:
A mad philosopher has sent a trolley car racing down the track toward five people tied to the rails. The people will surely die if the trolley hits them. There is a switch that will send the trolley down a different track, where the philosopher has tied only one person. You are the only person able to throw the switch, saving the five but killing the one. Would you do it?
Think about it a bit before you answer. Purely from a numerical standpoint, throwing the switch makes sense: one for five. This is the utilitarian view. But there are many who refuse, often saying something like, “I don’t know the people. That one person could be a better person than the other five.” This reflects incommensurability.
There are many variants to the trolley problem. Some omit the mad philosopher, making the whole thing an accident. This can shade the scenario because there is no one to blame but you; in the first example, you can say that the death of the five people is the mad philosopher’s responsibility for setting up the problem in the first place.
Another variant is the so-called “fat man” scenario. In this one there is no switch, but you are standing on a bridge over the tracks next to a fat man, whose body could stop the trolley (yours won’t) so you have to decide whether to push the fat man over the railing onto the tracks.
You are Inconsistent
If you think you have a firm answer for the trolley problem, there are variations aplenty to give you cause to doubt yourself.
If you say you would never throw the switch, consider that every year some (small) number of people die in accidents caused by police and fire response teams answering 911 calls. So if there is a fire, you are changing your answer to the trolley problem if you dial the phone. Another example is driving an SUV — you and your passengers are safer, the people you have an accident with are less. There are other examples.
If you say you would throw the switch, consider the following scenario: a surgeon has five patients waiting for transplants, and their outcome doesn’t look good. The surgeon discovers that another of his patients is a perfect match for the other five. Hypothetical, yes, but from a utilitarian viewpoint equivalent to the fat man variant. So would you have the surgeon kill the one patient and give kidneys, liver, heart, etc. to the others?
Don’t feel bad. As far as I can tell, philosophers (who do this for a living, how cool is that?) don’t have a firm answer for the trolley problem.
The Trolley Problem is Everywhere
It isn’t cited all that often, but there are many scenarios that map back to the trolley problem. There’s the famous “If you had a time machine, would you kill Hitler?” question. As an aside, here’s a really funny short story on using time machines to kill historical mass-murderers. The 911 phone call question and SUVs are others. Any time you balance one person’s safety against another’s, you’re participating in a form of the Trolley Problem.
The question of torture is another form of the Trolley Problem. Suppose the mad philosopher has put five people in the way of the trolley but the alternate track has no one on it. However, the philosopher has put a padlock on the switch. Only the philosopher knows the combination to the lock, and you have only a minute to get the answer. What would you be willing to do to get it?
There are numerous complexities in trying to translate this to the real world, including the fact that coerced information is suspect at best, and potential torture victims are rarely so obliging as to place people in as obvious and timely a predicament as tying them to a trolley track. That said, it’s interesting to me that we often discuss this in terms of far more vague and unlikely scenarios (“a terrorist has set a dirty bomb to go off in Manhattan in one hour…”) when I think it would occur far more often in more mundane and practical scenarios: imagine a platoon of soldiers who capture one member of an enemy formation. Obviously the prisoner likely has time-sensitive information on the location, plans, and capabilities of the enemy formation that will have a high-probability impact on the survival of the platoon. In this very real situation the potential value of torture is clear, and yet we don’t authorize it.
Psychologically there’s a difference between the probabilities of a 911 call and the certainties of the Trolley Problem or of torture. People are willing to put some unknown others in slightly greater risk in order to achieve a near-certain benefit, and no one argues that. Something more concrete, like waterboarding a man, in hopes of achieving something more vague, like general information on far away enemies with indefinite plans, is a harder thing to justify. But it’s difficult to rule out as the (potential) situation moves closer to the trolley tracks. I don’t have a good answer for the surgeon variant, though.
Philosophy is hard, so it’s no surprise that this question provokes controversy.
Note: I’m keeping an informal list of people who have been waterboarded, and their reactions.