Hmmm...for me, I personally reject the notion that all life is meaningless, because I find it a rather horrid worldview to adopt, and in the end sort of useless. Moving on from there, it seems to me that killing in defense or yourself or a loved one, assuming that you are not the aggressor, is not only justifiable emotionally, but logically as well. I used to be an absolute pacifist, and I do agree with the notion of the cycle of violence - but if someone else is definately going to commit an unprovoked violent act, and I would argue is therefore more likely to do so again, or I'm going to commit the violent act to stop them, I feel justified in taking their life
if need be. I would perhaps agree with capital punishment in theory, but for practical considerations I disagree with it. It would seem that is both way to easy to kill someone who is innocent, and that it gives a tremendous amount of power to the government with can be abused. In short - I kill in self-defense
: State sanctioned killing of people for same offense