As I said...you seem to have a black or white position on this. — Frank Apisa

That is because I find suffering completely unacceptable.

It's easy to justify harming others. I don't understand OP, you're asking if there's any "what" justification? Reasonable? Sustainable? I think we live in a blessed society where there are very few long-term sensible reasons for harming others but that's only because there are punishments for it. If you harmed someone else and gained something of substantial value from it and there were no repercussions, isn't your condemnation rather meaningless?

In a society with the proper protections, hurting others is the same as hurting yourself or at least taking a big risk. I'm against hurting yourself or taking huge risks like that, I can't accept that as a rational way to behave. Revenge, for the ego, jealousy and so on, fleeting and if you could just deal with it some other way, then you and your family/friends would be so much better off.

If it were 100% certain you could kill someone for 1-10x your annual salary with 0% chance of any kind of repercussions, external or internal consequences. Curtailing yourself for your ideals has an appeal to some people but for specifically that person, a choice to harm seems pragmatic.

Some other things I'm willing to argue about
- If you're raised to harm others
- If you live in a place where harming others is rewarding (Joining a violent group in a poor country or a violent political party like Nazi Germany/Soviet Union)
- Dealing with bullies/offensive remarks/actions (I wouldn't but I think their argument is better than "no harm irrespective of circumstances"
- Use of necessary force to reclaim stolen property
- Retaliation (sticking up for yourself despite non-violent solutions existing)
- I'd include a bunch of political/military reasons for violence but I assume we're leaving those out

I could probably come up with more, significantly I'm not saying the aforementioned justifications for violence are necessarily the best options. Most of the time, there's a better way of handling things but in so far as would they have justification for doing what violence in those situations, I'd say they did. Not really advocating violence, I can't think of any non-self defence reason for me to hurt someone but I think reasonable justifications exist (if that was what you're asking for, you didn't say).

I'm not saying the aforementioned justifications for violence are necessarily the best options — Judaka

I think that if something is not the best option then it is less reasonable.

I think harm leads to more harm. For example bombing Germany and Japan in world war two was a response to harm. There would be no justification for the second harm if the first harm hadn't happened.

I think we need to start from the first cases of harm because I think if there was no harm in the begin there would be less harm after. Things like social inequality and poverty can cause further chronic harms.

I don't know exactly the most appropriate way to define "Justification" there are various definitions but I am looking at it in a more morality and reasoning sense.

I think if you killed someone and made a million dollars on the surface that seems to give a reason for killing them. But very few people believe that is acceptable. But also if you turned that into a moral rule, that you could kill someone for profit then it would create a war of all against all. I think reasoning would lead to cooperation and harm minimization.

Another thing is that when I talk about justification I am not just looking at the person committing the harm for whatever reason but at the victim, can you justify to the victim what you have done to them.

We're am odd mix, I think, of sort-of-chimpanzees and abstract thinkers. The chimpanzee bit would hit back when hurt, then forget it, but the abstract bit would either go in for large-scale revenge on the basis of an alleged continuous consciousness that was harmed and should be avenged or that the offending consciousness should be reformed, or forgive and forget on various grounds, especially that the alleged offending and harmed personalities had disappeared a few seconds later. I think we should stop violent harm, because it is difficult to live together if it is accepted.

It is less reasonable but they're nonetheless more or less culturally accepted examples where causing harm has justifications that many people are sympathetic to. You have decided that the victim also needs to agree and realistically, in some of the cases I provided, they might. If you insult someone too viciously, you may be expecting violence and feeling you yourself might respond violently, it is possible.

It is just you who decided that the victim needs to agree though, I don't accept that as a pre-requisite to a fair justification. I think we also have different estimations of how much violence morality prevents, I lean more towards people being scared, logical, lacking motive and desire, empathy and many other things before moral obligation or rules.

I am a pragmatist, violence is generally not helpful because it has many negative consequences. Your argument relies on some lofty premises, why should I play by the victim's rules? I'm the one who has to justify my actions to myself, the law is already set against violence, convincing myself and my friends, that's all that's within my power to attempt to do.