> For example you could kill someone and take their organs to save the lives of 4-5 people. Is it rational that we're not allowed to do that? Why do some people get to keep 2 kidneys when there are others with none?
There was a pretty good short story, "Dibs" by Brian Plante, about that published in the April 2004 issue of Analog Science Fiction and Fact.
Everyone was required to be registered in the transplant matching system. Occasionally you'd receive a letter telling you that someone was going to die soon unless they got one of your organs. That person now had dibs on that organ, and if anything happened to you before they died they got it.
Usually you would get another letter a couple weeks or so later telling you that the person no longer had dibs, which generally meant that they had died.
Sometimes, though, you'd get a second dibs letter while you already had one organ under dibs.
And sometimes you'd get a dibs letter when you already had two organs under dibs...meaning if you died now it would save three lives. At that point you were required to report in and your organs were taken to save those three other lives.
The story concerned someone who worked for the transplant matching agency who got a second dibs letter and was quite worried. He illegally used his insider access to find out who the people were who had dibs on him, and started digging around to try to convince himself they were terrible people who didn't deserve to survive to justify illegally interfering, if I recall correctly (I only read the story once, when it was in the current issue).
I don't remember what happened after that. I just remember thinking that it was an interesting story and explored some interesting issues.