There's a well-known thought experiment in ethics called the "trolley problem," which goes something like this: A madman ties five innocent people to a trolley track. A runaway trolley is heading toward them, and moments later it's about to run them over. But you can pull a lever to get the trolley to go on another track. The problem, though, is that the lunatic tied someone up on another trolley track. Faced with this situation, will you pull the lever? The trolley problem was firs...