Terrence Tomkow in his own blog:
A runaway trolley is coming down the track. It is headed towards five people who cannot get out of its way. A Passerby realizes that he can save the five by throwing a switch and diverting the trolley down a siding, but he also realizes that if he does so, the trolley will kill a Lone Man standing on the siding.
Should you divert the trolley? Lots of folks say, “Yes!” Whether or not they are right is an interesting problem but it is not what philosophers call “The Trolley Problem“. That problem involves a different case:
A runaway trolley is coming down the track. It is headed towards five people who cannot get out of its way. A passerby realizes that if he pushes a nearby fat man onto the tracks his bulk will stop the trolley before it hits the five, though the fat man himself will be killed.
Most people, including those who think it is okay to turn in TROLLEY, think that it is not okay to push the FAT MAN. “The Trolley Problem” is how to reconcile these two answers. In both cases it seems you can do something that will save five people but only by killing one. How can anyone think it okay to turn in TROLLEY but wrong to push the FAT MAN? What difference is there between the two stories that can possibly make a moral difference?
In the almost forty years since Judith Jarvis Thomson first posed the problem in this form there have many attempts to solve it but none is generally accepted as successful. Indeed a general consensus seems to have developed that the “folk intuitions” (as philosophers call them) about the difference between these cases are simply irrational.