Have the psychologists got it right?

Moral dilemmas are very fashionable in science. A number of the softer -ologies have over recent years produced some cunning thought experiments to test how we react, and why we react, to moral challenges.

One of the most famous of these is the trolley dilemma. (I believe this refers to what we'd call a tram in Europe, rather than the sort of things desserts used to be served on.) Test subjects are presented with a hypothetical choice. A runaway trolley is about to smash into five people and kill them. Would the subject press a button which switched the trolley onto another track where it would kill just one person? Pretty well unanimously they answer 'Yes,' even though they are going to be responsible for that individual's death.

Then the subjects are presented with an alternative. They are to imagine themselves on a bridge over the trolley track. A runaway trolley is about to shoot under the bridge and kill five people. The only way to stop it is to push a very heavy person, standing next to them, off the bridge. This will stop the trolley but kill the heavy person. (The subject is too light to stop the trolley.) What would they do?

How would you answer? Most say no, they couldn't take this action. This is used by the -ologists to show how emotional connection changes reasoning processes. In the first case we have a cold, dispassionate button push. In the second we are directly killing another human being with all the emotional baggage that carries.

I can see the thinking behind this, but I don't believe the experiment as stated proves the point. (It may be there are other controls that aren't mentioned in the way the experiment is usually described.) There is a not just an emotional difference between the two cases, but a cold logical difference too. In the first case I can pretty well guarantee the outcome will be as described. But in the second case there are two big flaws. First I have to be able to push an extremely heavy person off a bridge. Would I be strong enough? Okay, you can get round this by saying the big person happens to be perched on the parapet, standing on one leg for a photo pose.

More significantly, the heavy person's body has to stop the trolley. Simple physics tells me this is unlikely. Okay, there are circumstances where it might happen, but I certainly can't guarantee it. So the choice is not just between a low emotional connection and a high emotional connection, but between a certainty and a long shot. And that very much changes the decision parameters.

I have no doubt the experimenters would reassure test subjects that the heavy person would definitely stop the trolley - but such reassurance can't stop the part of the brain that weighs up the odds saying 'Nah, it's not going to work. I'm going to kill this guy, and the trolley will still plough into the others.' Test subjects would always have doubt about the second solution.

For me, that makes the whole experiment flawed.

Photo from Freefoto.com


  1. Reminds me a little of the role-playing exercise we had to do at college, for business studies of all things, we were split into teams of five, each team given the same scenario - you're all doctors, and six people are rushed into hospital, all needing a transplant/operation - can't remember what it was - but upshot was you only had facility for one of them to receive the treatment. Who to pick?

    I don't recall the various characters, but for example, you'd have something like:

    A young child prodigy, brlliant in maths/science I think, with the talent to, potentially, save X thousand of lives during his career;

    A popular, charismatic politician (I know, bear with me on this one...) who is about to broker a groundbreaking peace deal in an area torn apart by decades of fighting;

    A young mum, whose baby has survived a horrific car crash, but her husband and other children are all dead;

    And three other people, all with very good reasons for being kept alive.

    Nothing like the test you're talking about, Brian, but it was a fascinating project, and, although you'd been studying with your peers for a year, you got insights into the way they thought which made you see some of them in a completely different light.

    There was, of course, no correct 'answer'. But it sure was fun debating.


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