"...if we disagree because I see what I want as just and the alternative as unjust and you see it the other way around, compromise looks to both of us like moral treason."
This is the bane of the human condition. We come up with rules we should all live by, then we encounter contradictions or logical impasse and can't come to a decision or compromise and end up warring.
There is no answer to this problem and humans are totally doomed as a result.
That we are still surviving is a miracle.
This is also why religion is a dead end. A complete, and total, yet remarkably DEAD dead end.
You can't live in a society with a god and expect to obey his/her rules "properly" and also compromise here on earth with people who don't believe in your god.
If your god is not all powerful, there is no point in worshiping him/her. So you MUST fight.