A view, with which I disagree, often put on that interaction by many students of aikido is that the outcome must be non-violent. In my mind, the interaction itself is violence, and therefor cannot be non-violent. However, I do agree and believe that to be aikido, the outcome should result in the least possible harm to all involved, starting with myself and extending out as far as possible.
I don't believe that this means the least possible harm in that instant. I believe that this means the least possible harm for all time. This might necessitate serious injury or death in the process of doing what is necessary.
Here again one could ask a similar question as before. Who has the right to determine what is "necessary?" If you give yourself this right, can you be sure you have enough wisdom or information to make this determination? If you decide that it is necessary to kill someone because you think
that this will cause the least possible harm, how do you know that you have made the right decision? What if it turns out that you are wrong?
And how is making such a decision about someone else's fate in the context of aikido any different from making in the context of karate, military force, the criminal justice system, domestic violence, etc. Any of these forms of hurting or killing others can be rationalized or justified as being "necessary" and "good" in the long term, although obviously how necessary or good they actually are is a matter that can be debated. I think anytime you grant yourself the sole right or responsibility to determine that violence is necessary you put yourself on very questionable moral ground.