One particular hypothetical scenario... involves a runaway trolley, five helpless people on the track, and a large-framed man looking on from a footbridge.
You know that if you push the large man off the bridge onto the tracks, his body will stop the trolley before it kills the five people on the tracks. Of course, he will die in the process. So the question is: Is it morally permissible to kill the man in order to save five others?
In surveys, most people (around 85 percent) say they would not push the man to his death.
[Princeton psychology post-doc Joshua D.] Greene and his colleagues described the finding as a partial victory for David Hume, the British philosopher who wrote that reason was a "slave to the emotions." But more precisely, they described moral decision-making as a process in which reason and emotion duke it out within the mind.
I am a David Hume fan, but I don't think Hume applies in this case. Would I kill a man in order to save five others? Yes. But would I push a man towards the path of an oncoming train in the distant hope that his body would slow the train enough that it would stop before hitting five people further down the track (but close enough for us to look on)? Are you kidding? With time to reflect, I might guage the odds of that gambit working at something in the ballpark of one in five, and probably less. The probable death count is at least as high if I push as if I don't. All things vaguely equal, it's perfectly reasonable to choose to not actively kill someone.
And that is exactly what happens:
Often, this scenario is paired with a similar one: Again, there are five helpless people on the track. But this time, you can pull a switch that will send the runaway trolley onto a side track, where only one person is standing. So again, you can reduce the number of deaths from five to one-but in this case most people say, yes, they would go ahead and pull the lever. Why do we react so differently to the two scenarios?The authors chalk the difference up to emotional contact--it is one thing to flip a switch, another to kill a man by pushing his body with yours. I disagree: I think you can't ignore the difference in the clarity of the choice.