for someone who is morally upstanding, if the situation gets far enough that there is engagement, you have done what you can to try and avoid the conflict, but it happens anyway, be prepared to hurt someone or be hurt. this scenario is the worst case scenario. hopefully in most cases you can mitigate the instigation with talk, posture and diplomacy.
of course you have the degree in which you've been able to assess a situation...who is assaulting you, if they have friends, where you are, are there weapons involved, escape routes, do you have back up, etc.
all factors considered, when it comes down to trading blows or wrestling a stranger I have to assume that they will not hold back, they are willing to hurt me seriously, and that they are skilled at doing so.
this is pretty much the way i've always approached stranger conflict. in most all cases i've been able to get through without having to fight, but not always. there have been several times where it doesnt matter what you say or do, that person is intent on hurting you regardless of anything you can do to de-escelate the situation.
in that case i feel its best to attack without restraint. if you are in a situation where you are actually capable of restraining yourself with that person during a fight, then you severly outclass them and you screwed up in the first place letting things get that far, and after your dump or drop them a couple times they will stop or they will get help.
retaliation can be a real concern, but that comes down to where you are, who you're in an altercation with, and who you are. in most cases you won't be dealing with a gangbanger or a thug that's going to take it that far, but thats a judgment call at the time. again thats primarily going to come down to location in many cases.
when it comes down to it and you find yourself in that situation, its best to fight as if your life depended on it, because you never know, it just may. even if that person is not trying to kill you but just hurt you, accidents happen, people get carried away, and 'stray bullets' can kill.
anyone who has been in a 'fight for your life' situation knows the difference in the way you will behave and react and what you will be willing and able to do. i've been there once when i was very young and it changed my mindset towards violence for the rest of my life. you push me that far, i will do my best to make sure i'm the one that prevails.
For whoso comes amongst many shall one day find that no one man is by so far the mightiest of all.