An article in The Boston Globe on the recent research about how we make moral judgements.
"MORAL PHILOSOPHERS and academics interested in studying how humans choose between right and wrong often use thought experiments to tease out the principles that inform our decisions. One particular hypothetical scenario has become quite the rage in some top psychological journals. It involves a runaway trolley, five helpless people on the track, and a large-framed man looking on from a footbridge. He may or may not be about to tumble to his bloody demise: You get to make the call.
That's because in this scenario, you are standing on the footbridge, too. 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.
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?"