Earlier quoted context omitted.
> Who designed the gas chambers at Auschwitz? An engineer did that, too. Well, given how unimaginative a leap the national socialists took from the national fumigation program to the gas chambers, I doubt there was much more to it than "take bug poison room tech, use it on humans". There's no such thing as an "engineer" in the real world, and there's almost always somebody more unscrupulous, devout, or patriotic than…
> ... there's almost always somebody more unscrupulous, devout, or patriotic than you who knows or is willing to learn what it takes to finish the job ... If you believe that doing something is wrong, the idea that someone more unscrupulous will do it if you do not must not be used as an excuse for doing that thing yourself. Giving in to this notion will prove yourself to be the one who is unscrupulous.
1. If you're on an active battlefield, both sides have already agreed that killing people is morally justified.
2. If the enemy is shooting at you, he is not interested in the ethics of killing someone on a battlefield.
3. If ethics helped wars end, there would be a US Army 27th Ethics Brigade to parachute in, but there's not and probably never will be.
If on a battlefield, given a choice between holding scrupulous ideals and living, most people would choose living.