Thought experiment: trolley problems.

Today’s thought experiment will in fact be 3 thought experiments. As these thought experiments are put forward, I recommend considering your answer and make a decision as you read each thought experiment. This is because the 2nd and 3rd thought experiment may influence your decision on the 1st.

The first thought experiment comes from Phillipa Foot. Imagine there is a runaway trolley about to drive into 5 people. You have no means of saving the 5 people other than a lever you have access to that will divert the trolley onto another track. However, there is 1 person on the other track, which will be hit by the trolley if you pull the lever.

The queston Foot asks us is: Would you pull the lever and have 1 person die or would you not pull the lever and have 5 people die?

After making your decision, consider this thought experiment made by J. Thomson: There is a runaway trolley about to drive into 5 people. You have no means of saving the 5 people other than pushing a fat man off a bridge who will fall in line with the trolley and will be large enough to stop the trolley (the assumption is that the fat man is able to stop the trolley but you are not, ruling out the possibility of self-sacrifice).

The question Thomson asks us is: Would you push the fat man off the bridge and have 1 person die or not push the fat man off the bridge and have 5 people die?

After thinking about this thought experiment, the last is also by Thomson, which is: You are a doctor who has 5 patients that all need an organ donation to survive, each needing a different organ. And they need them in the next 24 hours in order or they will die. You have a patient come in who is compatible with all of the other patients who would be able to donate these organs, but of course would die in such a procedure.

The question Thomson asks us is: would you kill the patient in order to save the other 5, or would you not kill the other patients in order to save the other 5?

Were your answers consistent or inconsistent? Did some answers involve saving 5 people and others not involve saving 5 people? Do you think all 3 thought experiments are morally the same? Or do you think there are morally relevant differences? If yes or no, why or why not?

Published by

Andrew Tulloch

I have a Bachelor of Arts majoring in Philosophy and Sociology, with a Political Science minor. I also have an honours degree in Philosophy. I am currently studying for my PhD in Philosophy.

8 thoughts on “Thought experiment: trolley problems.”

    1. Thanks Jason, yes it’s a good ol’ classic. My Phd will be heavily focussed on thought experiments so at the moment I’m practicing how to express them to the public 😊. Loving the creative writing tips! They’re hping to be reslly useful when I start to attempt thought experiments of my own 😊

      Liked by 1 person

      1. Thought experiments coupled with creativity can certainly lead to out of the box perspectives! Hopefully you’ll enrich your classroom with creative writing prompts, esp in your intro to philosophy course. It’s a great way to get all the students involved; in particular the introverts, who have a tendency to avoid group discussion. By giving the students the option to address three different topic questions (creative writing prompts) written on the chalkboard, all relevant to the lesson of the day of course, then allowing them 5 to 10 minutes of QUITE TIME to write out their thoughts on paper, followed by having a handful of them read aloud their notes, the dialectical synergy of group discussion will naturally flow. That is – like most dry profs – you won’t get stuck trying to rip responses out of people. If anything, you’ll have to find more constructive ways to regulate classroom dialogue. Envision all your students leaving the classroom feeling enthused and eager to share their discovery with another human-being!

        Liked by 1 person

  1. As far as I am concerned, such thought experients are ridiculous to even ask. This untenable situation will never happen. One person tying 5 people to a track woukd be hard to accomplish, and then asking a fat man to stand on an overpass so that mhe might be used to stop the trolley from running over the 5 people tied to the track is just insane.
    Why not just lie on the tracks and see if your body will stop the trolley. Put your own life on the line, not that of someone else who doesn’t even exist. Now, what will happen to you? That is a much more pertinent answer!

    Liked by 1 person

    1. Thanks Rawgod,

      Your objection is one shared by many philosophers, which some call the ‘objection from modality’. This objection is that when thought experiments are modally bizarre and involve worlds distant from our own, the thought experiment is illegitimate.

      My response is that this objection applies depending on the question being asked, or the conclusion the thought experiment is trying to make. For instance, the original trolley problem was made to argue for Utilitarianism. Utilitarianism is the view that we should always do whatever creates the most utility (this may be happiness/pleasure/preferences/etc).

      So, does the degree of plausibility matter to the Utilitarian when answering the trolley problem. Although some philosophers would be on your side and say yes, I would say no. I say no because Utilitarianism as an ethical theory is meant to be universal. This means it should apply in all possible worlds. So, even though the circumstances may be wildly different to what we would expect in our current world, it should not stop the Utilitarian from saying “yes pull the lever!”.

      As you can see, the purpose of the fat man although also wildly bizarre (denies our current laws of physics for a start), this should not be the thing that drives our basic reaction that this would be morally wrong to do, even though it would (at least in this bizarre world) save more lives.

      That is not to say that bizarre worlds are always legitimate, only that we should think about what question we are trying to answer.

      Thanks again,



      1. I agree with thinking about something in advance. Then, should the situation ever arise, you have considered different actions. So, looking at the reality of the situation, you can look at it more realistically,and make a better decision on how you are going to act, or not act, in that moment.
        Actually, while I do not like implausible situations, it is really thought experiments I object to. As you say, things depend on what answer the experimenter is seeking to find. That causes a bias as to how the question is asked, and may result in the experimenter overlooking data that isnot amenable to his or her goals.
        No thought experiment should ever be designed to bring about a desired outcome, but rather should inspect the results to see what is actually being said.
        Utilitarianism is not a philosophy that spoke to me in university. First, like you said, it is not a species-wide condition. Second, it does not promote social well-being. Just the other day one of Trump’s henchmen said that since senior citizens .make up only 2.5% of the American population, AND they are no longer productive, they dhouldn’t be given medical help. That is Utilitarianism speaking. Kill the oldfolk. I guess I don’t count, being 70. But kill all the old folk, and kill all their wisdom with them.That would be the end of society. Not a good thing.

        Liked by 1 person

  2. hi Mr Tulloch, I do understand that this is a ethics/ morality thought experiment. and is ,thus ,taken in isolation. However, I feel that one must look out how one derives one’s morality and ethics;e.g. peers, parents, religious guidance, socio-economic environment etc. So if one is to make a decision that would involve free will, whatever decision you make will be correct based on your morals and ethics, yet if one has been instructed in ethics and morality then no free will decision has been made….. Determinism??? well if that is the case, again, whatever decision you make will be the correct one because the outcome has already been determined …. perspective and purpose become irrelevant.
    what do you think?
    thank you for your time and consideration

    Liked by 1 person

    1. Thanks Simon,
      Quite a bit to address there, so apologies if I miss some points. Regarding where we get our ethics from, yes it is an interesting question and I do not have a definiitive answer. I do happen to be a determinist, so I would say a great deal would come from some mixture of all those factors. Application of praise/blame can be tricky based on how you treat these in the face of determinism. Say you’re a consequentialist, you could say that praising and blaming others produces better consequences, even if they were determined to do what they did (I’m not in love with that approach but it is one way to tackle it). I highly recommend Bernard Williams’ essay “internal reasons and the obscurity of blame”


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