To me, i’d say that its nice to have the confidence knowing a good martial art can give you. Plus, its fun to learn something with others. Or to have a sport. However, there are two important things to know first that martial arts may or may not teach you, and they relate alot to the discussion of streetfighting earlier in the thread.
First, learn how to diffuse the situation so there’s no fight at all. If this isn’t the issue and you’re being mugged or something, they’ll likely have a weapon and probably be willing to use it, so hope for the best that they wont and give them what they want so they’ll leave.
If you have a good opportunity to ‘stop’ them then you can take it to the next level (my second thought)–which is going to also put you in danger if you don’t get it right. Another thing that applies here is knowing where you should and shouldn’t be and when.
Second, if its inevitable that you have to have a physical confrontation with someone, then assume your life is in danger and do your best to quickly end the confrontation. Knowing how to hurt someone doesnt take much study. We all have plenty of soft tissue that can be easily damaged and that damage will usually cause enough pain to stop someone.
Just remember you can poke out eyes, rip off lips and ears, and crush a throat or testicle with little pressure. Not to mention punch/stab someone with a fistful of keys. All of these things should cause enough of a distraction to give you time to haul ass before they can use a weapon, their friends show up with weapons, or the cops show up. Or so you can hope…I’ve punched a few throats, poked a few eyes, slapped a few ears, and generally thrown people against a wall or the ground as hard as I could to end a few bar and street fights and haul ass. I’ve taken a few painful shots too. Just what I got from growing up with fight happy idiot friends i guess. Luckily no one was hurt too badly and I’m not in jail.
Outside of that kind of stuff, i’d say look for a martial art that teaches you to hit hard, defend, and control. Something you have fun learning and something that gives you alot of serious sparring practice so you can get used to hitting and taking a hit with power. Its that first hit that does alot of people in, as it can be a shock. But if you get used to it…
[edit] I just wanted to add that most fights i’ve seen or been in were at, outside or in a party, a bar, an after hours restaurant, or in traffic. Not counting mugger-types (thats only happened to me once). But with all those fights, it might’ve started between two people, but the first thing that happens is someone gets pushed or knocked down (the tackle is a major tactic) and all the friends start using them as a soccer ball. If there are lots of friends invovled on both sides, it turns into more of a brawl-and-run as the cops show. So, if its ever you against many, run hard and fast. Screw honor, it’s about survival. And you should probably zig-zag because crowds love to throw things. 