<i>Spur.</i> You’re standing by the side of a track when you see a runaway train hurtling toward you: clearly the brakes have failed. Ahead are five people, tied to the track. If you do nothing, the five will be run over and killed. Luckily you are next to a signal switch: turning this switch will send the out-of-control train down a side track, a spur, just ahead of you. Alas, there’s a snag: on the spur you spot one person tied to the track. Changing direction will inevitably result in this person being killed. What should you do?
<i>Fat Man.</i> You’re on a footbridge overlooking the railway track. You see the trolley hurtling along the track and, ahead of it, five people tied to the rails. Can these five be saved? The moral philosopher has cunningly arranged matters so that they can be. There’s a very fat man leaning over the railing watching the trolley. If you were to push him over the footbridge, he would tumble down and smash on to the track below. He’s so obese that his bulk would bring the trolley to a shuddering halt. Sadly, the process would kill the fat man. But it would save the other five. Should you push the fat man?
<i>Lazy Susan.</i> In Lazy Susan you can save the five by twisting the revolving plate 180 degrees -- this will have the unfortunate consequence of placing one man directly in the path of the train. Should you rotate the Lazy Susan?
<i>Loop.</i> The trolley is heading toward five men who, as it happens, are all skinny. If the trolley were to collide into them they would die, but their combined bulk would stop the train. You could instead turn the trolley onto a loop. One fat man is tied onto the loop. His weight alone will stop the trolley, preventing it from continuing around the loop and killing the five. Should you turn the trolley down the loop?
<i>Six Behind One.</i> You are standing on the side of the track. A runaway trolley is hurtling toward you. Ahead are five people, tied to the track. If you do nothing, the five will be run over and killed. Luckily you are next to a signal switch: turning this switch will send the out-of-control trolley down a side track, a spur, just ahead of you. On the spur you see one person tied to the track: changing direction will inevitably result in this person being killed. Behind the one person are six people, also tied to the track. The one person, if hit, will stop the trolley. What should you do?
<i>Extra Push.</i> The trolley is heading toward the five men who will die if you do nothing. You can turn the trolley onto a loop away from the five men. On this loop is a single man. But the trolley is traveling at such a pace that it would jump over the one man on the side track unless given an extra push. If it jumped over this man, it would loop back and kill the five. The only way to guarantee that it crashes into the man is to give it an extra push. Should you turn the trolley, and should you also give it the extra push?
<i>Two Loop.</i> The trolley is heading toward five men who will die if you do nothing. You can redirect the trolley onto an empty loop. If you took no further action, the trolley would rattle around this loop and kill the five. However, you could redirect the trolley a second time down a second loop that does have one person on it. This would kill the person on the track but save the five lives. Should you redirect the trolley, not once, but twice?
<i>Tractor Man.</i> The runaway trolley is heading toward five innocents. The trolley is not the only thing they’re threatened by. They are also about to be flattened by another, independent, threat. Rampaging in their direction is an out-of-control tractor. To redirect the trolley would be pointless if the five were in any case to be hit by the tractor. But if you turn the trolley away from them, it will gently hit and push, without hurting, another person into the path of the tractor. His being hit by the tractor would stop that vehicle but also kill him. Should you redirect the trolley?
<i>The Tumble Case.</i> The runaway trolley is heading toward five people. You cannot redirect the trolley, but you can move the five. But if you did that, the five would tumble down a mountain and, although they themselves would be unharmed, their body weight would kill an innocent person below. Should you move the five?
<i>The Trap Door.</i> The runaway trolley is heading toward five people. You are standing by the side of the track. The only way to stop the trolley killing the five is to pull a lever which opens a trap door on which a fat man happens to be standing. The fat man would plummet to the ground and die, but his body would stop the trolley. Should you open the trap door?