Paul Bloom and Matthew Jordan in the New York Times:
There is a dial in front of you, and if you turn it, a stranger who is in mild pain from being shocked will experience a tiny increase in the amount of the shock, so slight that he doesn’t even notice it. You turn it and leave. And then hundreds of people go up to the dial and each also turns it, so that eventually the victim is screaming in agony.
Did you do anything wrong? Derek Parfit, the influential British philosopher who died in January 2017, called this the case of the Harmless Torturer. Parfit first considered a simpler scenario in which a thousand torturers each turn the dial a thousand times on their own victim. This is plainly terrible. But then he explores a contrasting case where each of the torturers turns a dial a thousand times — each turn shocking a different one of the thousand victims. The end result is the same; a thousand people in agony. And yet morally it feels different, since nobody, individually, caused any real harm to any single individual.
This seems like the sort of clever technical example that philosophers love — among other things, it’s a challenge to a utilitarian view in which the wrongness of an act is reduced to its consequences — but one with no actual real-world relevance. But the world has changed since Parfit published his scenario in 1986.