A runaway streetcar is hurtling down a track and will kill a group of five unsuspecting people in its path. If you could pull a lever and divert the trolley onto a track where only one person will die, would you do that?
Or would you do nothing?
Alternatively, if your only other option was to push a very large man off a bridge into the path of the trolley, knowing that he would die but the trolley would stop, would you do that in order to save five people?
Most people say they’d pull the lever but not push the man off the bridge. But is that the right decision?
And what if the five people were children and the large man very old: would that make a difference?
The ‘Trolley Problem’ is a philosophical problem originally devised in 1967 by Oxford philosopher Philippa Foot and developed further by Judith Thomson at MIT. Among many questions it raises, it asks whether, if moral decisions are about outcomes, we need worry about the manner in which we achieve them; whether a passive decision is less culpable than one requiring action; and whether we take certain decisions because they are ‘right’ or only because then we feel better about ourselves.
The Trolley Problem is an excellent exercise for a crime writer, and expresses the kind of dilemma that DI Grace Fisher has to resolve in my new novel Shot Through The Heart.