So how come that no one could offer a resolution? The question is: “which ethical principle is PRIMARY, the one allowing self-defense (and defense of others) or the one against killing some “innocent” person?” Because these two principles contradict each other.
They do not contradict, they balance each other.
For example, if someone is coming after me with a knife and I have a pistol, I can act to stop them. If in the course of doing so, they die, that is the
unintended result: the intended result was that the attack stop.
If, however, the attacker was some person I really really hated so I took this opportunity to kill him, then the act I commit looks the same from the outside, but my
intention of killing the attacker makes me morally culpable.
We cannot directly and intentionally kill someone who is “innocent,” ie, not directly and imminently threatening us with death or grievous bodily harm.
On the other hand, if there is a man who has committed horrendous crimes who gets beat up in prison and is therefore close to death and he is a perfect match for me and I desperately need a heart transplant, I cannot remove his heart just a little bit early to save my life.
Altho he is not “innocent” in general, having committed horrendous crimes, he is innocent with respect to me at this particular moment, because, even tho I am in imminent danger of death,
he is not the one putting me into that danger.
The question is one of definitions and understanding the principles.