What’s the difference between the cases? There is quite a literature on this, including the theory that pushing the fat man triggers an emotional revulsion which flipping a switch does not. And answers to the effect that it is immoral to push the fat man are just attempts to rationalise this revulsion. That’s a cynical, but possible, explanation.
Another theory is based on intentions: by flipping the switch, you are not intending to kill the one person on the alternate track (you’d be very glad if they somehow escaped in time), whereas in pushing the fat man, you are intending to kill or seriously injure him (if he just bounces off the trolley car unharmed, without stopping it, then pushing him achieves nothing). This doesn’t quite work though, since you are presumably hoping that the fat man survives somehow.
A distinction that I haven’t seen discussed so much is the Kantian one: that it is wrong to use people as means to ends rather than treating them as ends in their own right. Flipping a switch doesn’t use anyone, whereas pushing the fat man off is clearly using him to stop the trolley.
This could also account for some of the distinction in the “honourable suicide” case: if I use myself to achieve an end that is of high ethical value (saving lives), then this is not in principle different from using my body to achieve any of my other (ethical) ends. (The Kantian has to grant some sort of exception to use of oneself, otherwise we can’t get up in the morning.) So I think this supports the sense that jumping off myself is morally permissible (and even commendable), whereas pushing someone else off isn’t.
I’m not so sure about the case where the fat man wants to jump himself, but needs help being lifted. That seems a little bit too close to assisted suicide, and the sense that this is wrong is probably based not on Kantian distinctions, but on whether it is a good social rule to allow killing in those circumstances. (It seems not, because the defence after the fact would always be “Of course the fat man wanted to jump! Prove that he didn’t!”)
What’s the difference between the cases? There is quite a literature on this, including the theory that pushing the fat man triggers an emotional revulsion which flipping a switch does not. And answers to the effect that it is immoral to push the fat man are just attempts to rationalise this revulsion. That’s a cynical, but possible, explanation.
Another theory is based on intentions: by flipping the switch, you are not intending to kill the one person on the alternate track (you’d be very glad if they somehow escaped in time), whereas in pushing the fat man, you are intending to kill or seriously injure him (if he just bounces off the trolley car unharmed, without stopping it, then pushing him achieves nothing). This doesn’t quite work though, since you are presumably hoping that the fat man survives somehow.
A distinction that I haven’t seen discussed so much is the Kantian one: that it is wrong to use people as means to ends rather than treating them as ends in their own right. Flipping a switch doesn’t use anyone, whereas pushing the fat man off is clearly using him to stop the trolley.
This could also account for some of the distinction in the “honourable suicide” case: if I use myself to achieve an end that is of high ethical value (saving lives), then this is not in principle different from using my body to achieve any of my other (ethical) ends. (The Kantian has to grant some sort of exception to use of oneself, otherwise we can’t get up in the morning.) So I think this supports the sense that jumping off myself is morally permissible (and even commendable), whereas pushing someone else off isn’t.
I’m not so sure about the case where the fat man wants to jump himself, but needs help being lifted. That seems a little bit too close to assisted suicide, and the sense that this is wrong is probably based not on Kantian distinctions, but on whether it is a good social rule to allow killing in those circumstances. (It seems not, because the defence after the fact would always be “Of course the fat man wanted to jump! Prove that he didn’t!”)