I am a pacifist of a sort. I do not believe in violence as a solution for conflicts and friction.
The other day, I was thinking about a person from my past, who brought much grief upon me. Given the opportunity, would I have eliminated that person to save me from pain? The answer was absolutely not. While they attempted to harm me in a multitude of ways, I would not have taken any violent steps to retort.
I found that reply to be relatively easy. I therefore asked myself, would I consider hurting, and even eliminating, another human being under different circumstances?
To test myself, I went to the extreme. Given an opportunity, if I lived in Germany in the 1930s, and knowing what we know today about Hitler, and if I had an opportunity to press a button and make him die, would I? With this question I found myself promptly responding with a yes. Pacifist or not, removing a person that brought so much evil and death into the world was a no-brainer.
This reminded me of a famous story, attributed, among others, to George Bernard Shaw, Winston Churchill, Groucho Marx, Mark Twain, and several others…
At a party, a man asks a socialite if she would be willing to sleep with him, if he pays her a million dollars. She blushes somewhat but readily agree. He then asks if she would still be willing to sleep with him for just a dollar. The woman blows a fuse and replies in anger, “Why, what kind of woman do you think I am?” To this the man replies, “Madam, we’ve already established what you are. Now we’re just haggling over the price.”
Following this line of thinking, I realized that since I agreed that I would be ready to kill Hitler, it means that under certain circumstances, I can be a murderer. Now it is just a matter of defining those circumstances.
Over the years, I came to believe that the word never is useless. I will never do this or that – whenever I state this, some circumstances will take place where I find myself challenged with a situation that calls for breaking the never statement. Thus, I avoid, to the best of my awareness, the use of the words never and always. They are tricky words. Stating that I would never steal, is correct for me right now. But what if I find myself in a situation where my kids are on the verge of starvation, and the only way for me to feed them is by stealing a piece of bread? This is but one example; there can be extreme circumstances for almost every possible scenario of never and always statements.
Back to the question of killing. Would have I killed Stalin? Likely yes. He was, in my opinion, a mass murderer, not much different than Hitler. These two characters are easy as they are on the extreme side of the scale. How about the leader of North Korea, or the Russian tyrant? How about certain political, religious and other such figures, who brought and continue to bring much death and pain to the masses? Here I found myself slow to respond. It is easier to execute persons who are no longer among the living. But when it comes to people who are still alive, I feel the burden of making such a decision, heavy for me to make. I would have gladly approved capturing such people, and placing them in front of an international court to decide, but for myself to pull the trigger, I am not so sure. So maybe I am not a born killer after all. Maybe there is still hope for me.
Open Heart Energy 
If you’re only killing after the offender is dead then you’re only reason must be vengeance. Were you to kill this person in advance because you know what you know now you would then be doing so for Humanity. But killing the potential offender in advance of any offenses is clearly murder.
I agree with the latter part of your comment. As for killing for vengeance, that was not the intent. The idea was to put myself in the shoes of a man in the 1930s who knows with unquestionable certainty what Hitler will do. In that case it is not vengeance but doing a favor to humanity, which is maybe what you meant. There was actually a Twilight Zone episode dedicated to this topic. It featured a man who was seeing into the future – whatever he saw when he shook another person’s hand, came to be. One day he shakes the hand of a future politician, and sees that this man, if elected, will start a nuclear war that will bring an end to this world. He needs to decide whether to kill that person and prevent this disaster, even though the politician had yet done nothing wrong. The 2002 Spielberg film Minority Report also tackles this topic. I do not see black and white on this matter.
Oh I completely agree with you and have not seen anything black and white in my quite long life. We’re one able to see into the future with certainty I would agree. And if seeing the future with clarity were possible then the knowledge would, I assume, be relatively known and perhaps widespread. I draw the line there only because my question generally is on these things who makes the final decision and if that decision maker is extraordinarily flawed in their thought then their action will more than likely be flawed. I have known, sadly, who believe the unbelievable and the untruthful and were they to then act, in which some cases they have, the result is tragedy. It’s fascinating discussion there’s no question and I assure you I live in a gray gray world. Well done!