just me again ...
Okay ... I've been thinking about this and the honest answer doesn't really answer anything except a very basic need. The need for survival of any species will usually produce a violent reaction to extermination ... why? because our egos do not understand an existance beyond life. We can rationalize and produce ideal afterlifes, we can create any number of beliefs, but they are all once again based on our ego. We demand the right to exist because we truly believe it is the basis of our lives and will go to any length to see it validated... this includes violence.
The act of violence is an act of supressing another, it creates an imbalance that says one Will, Idea or Ego will survive or become dominate enough to continue. It doesn't matter whether this act is done for the good of oneself or another, in protection or defense ... it is still a belief that you are right and will do anything up to and including violence to achieve that sense of 'right'... and that sense of right is driven by Ego.
I can honestly say that although I do not condone violence and usually avoid it at most cost, there are a few things that do provoke me to violence... one of which is protection of self and defense of kin. Which of course brings us right back around to survival of the ego driving me. I know it and recognize it for what it is. Using violence for good seems an oxymoron to me, how can it be so? Yes I understand the samples given and react one way or another to each of them ... but violence is something mankind doesn't even think of doing away with... it exists as a human state as much as love does... we label it with pride and justice... we resort to it as a means of validating our way of life. There is no easy answer here, except ... I don't think violence can be justified, we give reasons... yes and beliefs as well. But when we know its our ego driving these reasons, how can we actually justify it all.
Still more to think about... I'm just putting out my thought process at this point ....