The Trolley Problem


  • Thomson, J.J. 2008. Turning the trolley. Philosophy and Public Affairs 36: 359–74.

In a nutshell

The problem was first posed by Phillipa Foot (1967) "Abortion and the Doctrine of Double Effect". Discussed further and expanded by Judith Jarvis Thomson.

  1. The bystander (two options) case -
  2. The fat guy case -

The moral question

The moral question - What should we do in these two situations?

  • Standard answer - You may flip the switch in the bystander case, but you may not push the fat guy. Why?
    • One answer: In the first case the death of the bystander is an unintended consequence, but in the second case the death is part of the plan.
  • A utilitarian might disagree - You should flip the switch and you should push the fat guy.
  • Thomson (2008)'s new position - You should not in both cases. (on the basis of the bystander three options case)

Psychological and other issues

  • What do people think in general? Are the intuitions widespread?
  • Why do people think that way? What cognitive mechanisms underlie our moral judgments?
  • The connection question - Do findings in psychology and neuroscience have any bearing on the moral question?

Greene's dual-process theory

  • Moral judgment is a product of two systems: a more rational and impersonal abstract reasoning system applied to morality, and an emotional system that is less rational.

@personal moral dilemmas, as compared with impersonal and non-moral dilemmas, produced increased activity in areas associated with social/emotional processing: medial frontal gyrus, posterior cingulate gyrus, and bilateral STS (originally labeled ‘angular gyrus’). By contrast, impersonal and non-moral dilemmas as compared with personal dilemmas produced increased activity in areas associated with working memory: dorsolateral prefrontal and parietal areas. They found comparatively little difference between the impersonal-moral and non-moral conditions, suggesting that impersonal moral judgment has less in common with personal moral judgment than with certain kinds of non-moral practical judgment.@

  • Use fMRI to check brain activity when dealing with the trolley problems.
  • In the fat guy case,
    • areas associated with emotions are more active - medial frontal gyrus, posterior cingulate gyrus, angular gyrus.
    • areas associated with working memory less active - right middle frontal gyrus, bilateral parietal lobe.
  • People who are willing to push the fat guy over took significantly longer to respond - they have to override their emotional response.
  • The two systems can come into conflict, as in the crying baby case.

Category.Philosophy Category.Mind