This is an interesting question, really. If someone just randomly hits you and you return the favor by hitting him back, do you start the fight?
Or did he beg for a fistburger and start it by disturbing your personal space, I.E your face?
Hmm, an interesting thought. Well, itās not really a fight if only one person is doing the hitting. Thatās more like assault and/or battery. The first person who hits instigates the fight, but the retaliation starts it.
If someone randomly punched me in the face, Iād kick the shit out of them.
Then Iād claim self-defense, because technically it is.
Well if they hit my face, I would be so damn pissed and blinded by fury that I guess I would beat the hell out of him, or try.Other than that I still would start a fight because the asshole started it first.
Iām all for eye for an eye, but itās out of self-defense if youāre attacked first.
Whats it matter as long as you end it? 
But, really. Technically you donāt start the fight, because what causes you to hit back is the fact that the other person hits you, which can/will lead to more blows. Said blows only continue to go on because of the fist that was first thrown at you. And stuff.
Funny. Someone in the cafeteria yesterday threw something that hit me in the side of my head. Man, I was pissed, but I couldnāt figure out who had done it so I couldnāt very well do anything about it. >=/
If I find the fucker, Iām gonna punch him in the face.
It was probably Derek. Now go kick his ass.
Nah, I wouldnāt hit back.
Iād just walk on past, grab his pinky finger on the way, and then bend it all the way backwards. Thatās far more vindictive and effective than a mere fisticuffs.
I donāt think it was Derek.
As you know, Iām helping raise my sisterās four-year-old, so things like these DO come up. Iāve been telling him NOT to hit back, unless he canāt escape; that heās supposed to tell the teacher who is then supposed to do something about it. I donāt want my nephew to grow up thinking that violence is a good solution to things. However, you can bet Iāll show him to protect himself when heās old enough to run into people who might actually hurt him.
This reminds me of a quote by my favorite SF character ever, Commander Sheridan (from BABYLON 5):
"My father always told me: Never START a fight.
But always FINISH it." 
This is absolutely technically correct.
If someone hits you once and you wtfpwn them back, thatās not self defense, geesh. If you have a choice and enough time to think āHmm I think Imma slap a bitchā then donāt kid yourself Self defense is only inflicting harm if you have to, isnāt it? If there are other means that allow you to walk away from the person who hit you, but you choose to still give it back to them, then itās not defense.
Depends on who: Itās a whole lot more fun to break a pretty face than an ugly one. It always will be. You do more damageā¦ Itās also a lot more fun to kick hunks in the balls than nerds and geeks. You should try it.
The question isnāt if itās self-defense or not, though, is it, or is it that youāre starting a fight? Because if you start a fight to defend yourself, it is still starting a fight.