A train is racing toward five men, tied to the track. Unless the train is stopped, it will inevitably kill all five men. If a fat man is pushed onto the line, although he will die, his body will stop the train, saving five lives. Would you kill the fat man?

As David Edmonds shows, answering the question is far more complex, and important, than it first appears. In fact, how we answer it tells us a great deal about right and wrong.

‘This is a highly engaging book. David Edmonds’ reflections are full of insight’ ROGER CRISP, University of Oxford