Of all fictional treatments of this question, the one that stood out to me the most is the one in Three Worlds Collide because of its restraint from turning a psychological question into a moral question.
“Once upon a time,” said the Kiritsugu, “there were people who dropped a U-235 fission bomb, on a place called Hiroshima. They killed perhaps seventy thousand people, and ended a war. And if the good and decent officer who pressed that button had needed to walk up to a man, a woman, a child, and slit their throats one at a time, he would have broken long before he killed seventy thousand people.”
“But pressing a button is different,” the Kiritsugu said. “You don’t see the results, then. Stabbing someone with a knife has an impact on you. The first time, anyway. Shooting someone with a gun is easier. Being a few meters further away makes a surprising difference. Only needing to pull a trigger changes it a lot. As for pressing a button on a spaceship—that’s the easiest of all. Then the part about ‘fifteen billion’ just gets flushed away. And more importantly—you think it was the right thing to do. The noble, the moral, the honorable thing to do. For the safety of your tribe. You’re proud of it—”
“Are you saying,” the Lord Pilot said, “that it was not the right thing to do?”
“No,” the Kiritsugu said. “I’m saying that, right or wrong, the belief is all it takes.”
Of all fictional treatments of this question, the one that stood out to me the most is the one in Three Worlds Collide because of its restraint from turning a psychological question into a moral question.