How would you define "reasonable" as it is used in law? For example, you are allowed to use "reasonable force" when defending yourself. It seems to depend on how serious the situation was, whether it was possible to resolve it by peaceful means, whether you were ready to try those means and, finally, the relative strengths of those involved. Now, most men know, and they've probably grasped this from their earliest years in the school playground, that, when it comes to blows, fights don't stop until one of you is in no shape to do any damage to the other. The criteria mentioned seem a bit fuzzy to me. How can you convince a jury you were ready to try and talk your way out of it when the other person would have none of it and, besides, he was quick to land the first punch? Also you can strike the first blow and still plead self-defense. Of course, you again have the problem of convincing people that the threat was so great that you had no alternative, apart from getting beaten up yourself. Reacting calmly and rationally to a perceived threat is not easy to do.