The trolley problem is a thought experiment based an ethical dilemma described in its modern format by Philippa Foot in 1967. The problem can be described as follows:
- Assume there is a runaway trolley moving down the tracks where five people have been tied down. You are standing at a switch that can be pulled which will divert the trolley away from the five people, but one person is tied to the other track. If you pull the switch, one person will be killed, if you do nothing, five people will be killed. Which is more ethical, to pull the switch or not?
According to surveys, about 90% of people would pull the switch and kill the one person to save the five. There are many variations on this problem which try to determine how people think about this internally.
Personally, I think it is unethical to take action in any of the variants where only five people are involved, and my upper limit is pretty high. I hold this opinion because I think it's wrong, without consent, to kill an innocent person in order to save the life of people who are going to die. I have come to this conclusion by putting myself in the position of the one being sacrificed. Would I purposely kill myself to prevent the death of five strangers? No, because my life is worth more to me than five strangers. I also think that most people, despite claims of heroism, feel the same way, which is why so few people can be bothered to give to charities.
The "fat man" variant has the usual five people tied to the track with a trolley coming to squish them, but, instead of a switch, you are on a bridge that goes over the track. Beside you is a fat man who, if pushed onto the tracks, has sufficient mass to slow the the trolley before it hits the five. The question is, is it ethical to push the man onto the tracks killing him, but sparing the five?
Most people who believe pulling the switch in the original experiment is ethical suddenly change their minds when it is presented this way. Although the outcome is the same (through their actions, they are responsible for killing someone in order to save five lives), the specifics of the situation alter how people view it. In the original experiment, all six people tied to the tracks are victims, even if one of them would be safe without your intervention. However, in this variant, you have to sacrifice an innocent bystander. Also, in this case, you must directly cause someone's death rather than indirectly in the original.
The "loop" variant is a combination between the original switch problem and the fat man. Five people are tied to the tracks and the trolley is coming, you are at a switch, but, in this case, the switch leads to a track loop which returns to the main track before it hits the five people. However, a fat person has fainted on the tracks, and his bulk will slow the trolley before it hits the other five. Is it ethical to pull the switch and kill the person to prevent the death of the other five? This variant mixes the sacrifice of an innocent bystander with the indirect killing of the original.
Man In the Yard
In this variant, five people are tied to the tracks, with an empty trolley coming, and you're at a switch. If you pull the switch, the trolley will go down an unfinished track, derail, and slide down a hill. At the bottom of the hill is a person taking a nap, and they will certainly be crushed to death by the trolley. Is it ethical to pull the switch?
The idea here is that the sleeping person isn't just innocent, they're completely uninvolved with the entire affair. So, fewer people think that this is ethical to throw the switch compared to the original scenario.
For the people who wouldn't throw the switch in the original, you can change their mind by adjusting the number of people on the track. Even if they won't kill the one person to save the life of five, they might kill one person to save the life of fifty, or five thousand. You may have to change the structure of the problem when the numbers get really high, see the Alternate Situations section below. Pretty much everyone has a number where they will eventually change their mind.
There are a few variations where pretty much everyone agrees on the ethical solution. If there is a switch leading to tracks that bypass the five people tied to the rails and nobody dies, is it ethical to pull the switch? This isn't even a dilemma because nothing bad happens along one route, however, it can be useful for setting up the thought experiment.
Another variation is the "fat villain" variant. This is similar to the "fat man" variant, but, in this case, the fat man is the same person who tied the five people to the tracks and left them for dead. In this case, most people agree that it is ethical to kill the villain to save the people he was trying to kill.
A traditional criticism of the Trolley Problem is that it is so unlikely to happen in real life, it doesn't address a dilemma that ordinary people would face, and is therefore useless for learning about morality. However, with the increasing amount of self-driving cars on the road, this issue is becoming more real. In this case, the variation would be described as, a self driving car is driving down the road, when it suddenly senses five people on the pavement in front of it. It can't stop in time, and its only way to avoid them is to swerve onto the sidewalk where there is one person. Is it ethical to make the car swerve and hit the bystander, or let it hit the five people? Considering how many cars and people there are, this dilemma will almost certainly be encountered at some point and engineers have to worry about what to do. In fact, the possibility of this happening has led to a resurgence of the trolley problem.
This thought experiment can be placed in all sorts of different situations that alter how people answer the question. For example:
A man is in a hospital waiting room for a routine checkup, and unbeknownst to him, five people who were all involved in a terrible accident each need an organ transplant to survive. The surgeon discovers that by sheer luck, the man in the waiting room is a perfect match for all of them, but he will have to be killed to get all five organs. Is it ethical for the doctor to kill the man and harvest his organs without his permission in order to save the five patients? This is related to the survival lottery thought experiment.
However, my favorite alternate is this one: Several people have become infected with a virus that will cause them a horrible painful death. A doctor discovers someone who is immune to the disease, and can make a cure, but the person with immunity must be killed in the process. Is it ethical to kill them without permission to save the five? This one is a helpful because you can easily adjust the number of infected people. While it's easy to call it unethical to kill one person to save five sick people, suddenly things change when there are five billion lives at stake.
Combining the trolley problem with the Ship of Theseus problem.
Mixing in the teleportation is death problem.
- youtube.com/watch?v=bOpf6KcWYyw - BBC animated version.
- youtube.com/watch?v=1sl5KJ69qiA - Testing the trolley problem in real life.