29 January 2011

Ethics: The [Off His] Trolley Problem

One of the contributors to my esteemed blog's comments section sent me the following ethics problem. I will allow him to de-cloak if he feels willing to do so, but I absolutely refuse to let such a practical everyday ethical issue go unaddressed on this blog. Because these issues are important. If we are in the proposed scenario (and, let's face it, who is likely to avoid this?), we need to think carefully about how we will act. Take it away, Mystery Man! (oops - I revealed the sex there... that narrows it down...)

A brain in a vat is at the wheel of a runaway trolley. There are only two options that the brain can take: the right side of the fork in the track or the left side of the fork. There is no way in sight of derailing or stopping the trolley and the brain is aware of this, for the brain knows trolleys. The only living beings saved on railway tracks are saved in one, and only one, of two ways. (i)They can save themselves. (ii)They are saved by a brain-in-a-vat changing the direction of a runaway trolley.

On the right side of the track there is a single railroad worker, Jones, who will definitely be killed if the brain steers the trolley to the right. If the railman on the right lives, he will go on to kill five men for the sake of killing them, but in doing so will inadvertently save the lives of thirty orphans (one of the five men he will kill is planning to destroy a bridge that the orphan's bus will be crossing later that night). One of the orphans that will be killed would have grown up to become a tyrant who would make good utilitarian men do bad things. Another of the orphans would grow up to become a used car salesman, while a third would invent Pringles. The rest will consume carbon fuels and fatty foods at unreasonable rates.

If the brain in the vat chooses the left side of the track, the trolley will definitely hit and kill a railman on the left side of the track, "Leftie", and will hit and destroy ten rabbits on the track that could (and would) have been used to feed starving children. If the railman on the left side of the track lives, he too will kill five men, in fact the same five that the railman on the right would kill. However, "Leftie" will kill the five as an unintended consequence of saving ten men: he will inadvertently kill the five men rushing the ten rabbits to the local poor shelter. A further result of "Leftie's" act would be that the busload of orphans will be spared. Among the group of men killed by "Leftie" is both the man who wrote the theme tune to “Friends” and Michael Barrymore. If the ten rabbits and "Leftie" are killed by the trolley, the ten starving children will die and their kidneys will be used to save the lives of twenty kidney-transplant patients, one of whom will grow up to cure cancer by illegal experiments on death row inmates in Iraq, and one of whom will grow up to be the next Dr Who. The kidney patients will be operated on without their informed consent.

Assume that the brain's choice, whatever it turns out to be, will serve as an example to other brains-in-vats and so the effects of his decision will be amplified. Also assume that if the brain chooses the right side of the fork, an unjust war free of war crimes will ensue, while if the brain chooses the left fork, a just war fraught with war crimes will result. Finally, the brain in the vat knows that there is a bomb on the trolley, and unless it pulls the lever on the trolley the bomb will explode and kill it.

Question: The brain has no arms and can’t control the direction of the trolley. But what should it want to do?


  1. It is a really interesting subject but I think the “answer”, if there is one!, is less to do with robotic programmed logic or even moral absolutes and more to do with emotional responses driven by our genetic survival instincts. ie we are programmed to take most care, first of ourselves, then of our family, then of our friends, then of acquaintances, then of our local group, then of our national group and so on till we get to total strangers. Cruel though it seems, that is the way we are made and by and large, in reality, that descending order will guide "our brain in the vat" in most decisions about pulling the switch, regardless of the numbers game or any contingent effects down the line. Fact is, it appears that from the Western perspective, 6 deaths in Tuscon get more attention than 6,000 deaths in Africa. I guess the reverse perspective also applies.

  2. I own up...I'm responsible for this version of the problem.

    I'm trying to track down the original culprit...it may have been David Chalmers...


  3. By the way...there is an answer for this version of the problem...

    a cookie for the correct answer!

  4. It must assume that the Great Vat is in control, and pray unto it to give it guidance. Which would help.

    But, in reality, all brains in vats should steer the trolley towards the fat guy, regardless of other considerations.

  5. You guys are way too smart for me!

  6. Graham

    First you tell me there is an answer... fine.

    Then you tell me that there is a correct answer.


    What can you possibly mean by correct?

    And what possible good would giving me (assuming I could give the correct answer) a cookie do? What if I became addicted to cookies? Whose responsibility would that be?

    However, much to my surprise, I could be with Shane on this one; praying for guidance seems like a good thing to do, and Shane is right, it would help, but I'm not sure how, and that would mean I'd have to pray for guidance about the guidance...

    Anyway, what if the brain let the trolley decide?

    BTW, what kind of cookie?

  7. Peter, it's a cookie in a vat.

    The consequences of our actions are subject to chaos dynamics, like the weather, and no matter how big the brain or the vat, long term downstreamers like Graham describes are simply not reliably predictable - all we can do is assign probabilities, in the knowledge that the more distal they are, the lower they become. Furthermore, Graham has not (of course) enumerated ALL the consequences, e.g. Michael Barrymore may well end up destroyed, but on the downside we might lose Cheryl Cole, and Graham hasn't even made a nod to her! None of this information is available to our brain in a vat, so it is pointless.

    Graham has asked what our brain would *want*, and the answer to that is probably to be in a different vat.

    But if the options are limited to Jones or Leftie, the fat guy gets it every time. p=1.

  8. Shane

    You got all that just by praying for guidance?

    Master Vat: As quickly as you can, snatch the pebble from my hand. When you can take the pebble from my hand, you will know the answer.

    Caine in a vat: And how do you think I'm going to do that while I'm on this trolley?

    Having said all that, I'm not sure that wanting to be in a different vat would be helpful. What if the other vat was worse?

  9. "The only living beings saved on railway tracks are saved in one, and only one, of two ways...."

  10. And the vat can't change the direction of the trolley...

  11. And the brain can't save himself...

  12. (And please don't make your version of the correct answer religious. If you do Alvin Plantinga might get wind of it and turn it into a proof for the existence of God; or Tim Keller might turn it into an illustration in a sermon!)

  13. (Actually...if I had given the brain a voice there definitely would be a solution!)

  14. You do realise, Graham, that if you're heading towards a theodicical point here, it will turn out to be the silliest one in the history of post-Augustinian theobabble, and that will be quite an achievement.

    However, carry on - Peter needs his cookie :-)

  15. "And please don't make your version of the correct answer religious."

    So the brain can't ask Jesus into his vat?

    Jones: Leftie, run like blazes - there's a brain in a vat on a runaway trolley heading straight for you. I know, I know, it makes no sense, but now is not the time for questions.

    Is Leftie a Marxist?

  16. No theoretical point. It was meant to be a simple case of misdirection.

    (Actually, I think I missed a trick. I should have altered the scenario a little more...

    Instead of The brain has no arms and can’t control the direction of the trolley. But what should it want to do?

    I should have written
    Suppose brain-in-the-vat can pull the lever and can also call to Leftie and Jones...what should he do?)


  17. Well - I say meant...

    But really "it occurred to me afterwards"; and I think that it could be tightened up a little more.

  18. To be honest, Graham, I think you are paying too much attention to the Chancellor's vat increase.

  19. If the brain in a vat (and I'm beginning to feel some attachment towards it) were able to increase the speed of the trolley to 88 miles per hour, and was in possession of a flux capacitor able to generate 1.21 gigawatts of electricity...

    And with that I'm nipping out to church - perhaps I will have an answer by the time I get home.

  20. i couldn't quite be bothered to think this one through - but was simply left thankful that I am not omniscient, because it seems omniscience brings with it pretty big burdens.