This is a toughy.

I would be the first person to stop and help if there was a car accident or other type of emergency. However, before helping in _any_ scenario, it's important to see if there is any "danger of further injury" before becoming involved.

"Danger of further injury" says that you need to have a look around the scene to make sure that nothing will hurt you or anyone else by becoming involved. In a mugging, the robber could hurt you or the victim by being involved.

I would see how the mugging played out. If the robber just grabs a wallet and the victim happily hands it over, great - problem solved. I'll be happy to go over and call the police and wait with the person until they arrive or walk the person to where he/she needs to go.

If the burglary turned violent, then I might still get involved. Muggings are usually done without foresight or planning. Picking up a piece of wood, yelling for help and generally drawing attention to the scene may be enough to scare the robber away. If not, yeah... I'd go in swinging.

http://www.youtube.com/watch?v=ZFHN2Dk4gPQ

Yes, I would. I've been in similar situations before, and I know that I'm an "act, then think" kinda person. I will help regardless of possible consequences, and would later start wondering whether I put myself in excessive danger or not.

I've stopped a homeless shoplifter in full run, I've assisted in a car accident, I've offered to be a witness for a woman being harassed in EuroDisney (she didn't understand me, so in the end I couldn't really help her, but the guards had arrived by then). I'm definitely sure I would help someone being robbed too.

No, because I can't defend myself let alone someone else. But I will call the police.

I would only help if it was situation where I thought my assistance would bring about positive results for the person getting robbed. If I felt that it may be too much for me to handle, I would call the police.

Yes! I would jump in and chase and tackle the guy if I had to. Anything to help out. I can't say I've ever been put in that position before, but I have chased a small truck down a slight incline. It was headed for the road and the guy forgot to put his emergency brake on. I caught it in time, thankfully!

If a seemingly innocent person is being threatened with harm, I absolutely would help.

I grew up in a very rough area. As a skinny, uncoordinated and untrained teen I managed to stop a sexual assault on a crowded public bus. An obvious gang member held an attractive high school girl down with one hand and explored under her skirt with the other while she stood trembling and crying. He was being encouraged by three cohorts who were seated nearby. The attacker, the girl and I were all very close to each other in the standing room area and not one of the other passengers spoke in her defense. I didn't say anything either, I simply punched him as hard as I could in the side of the head, causing his head to slam into a pole. He collapsed stunned as the bus was pulling into a station. At least one of his friends went for a gun but then quickly hid it when saw the two nearby police offers at the terminal. The officers warned me not to ride that bus or use that terminal again for a very long time or I likely would be shot on sight. Even knowing this I would not have behaved differently if I had the opportunity to do it over.

I have been accosted by two knife wielding gang members who demanded my money. I told them no and successfully resisted until the police arrived to take them into custody.

I once intervened when I saw a woman being roughly dragged and smacked around by a guy on an otherwise deserted public sidewalk at night.

It is a moral duty to help your fellow person resist attacks. If every time someone attempted to prey upon another person they were dog-piled and beaten by every last person within hailing distance, crime would disappear. Several shooting massacres in this country involved the killer firing until they emptied a magazine, reloading, and repeating this cycle several times. That means that there were likely multiple 1-3 second intervals where people could have stopped the killing spree if they had the decency to act rather than allowing evil to transpire while they cowered.

Every last person on the planet should learn basic self defense skills and be prepared to use them in the aid of innocent victims. If this happened, the good guys would always outnumber the bad guys. Since the above unpleasant experiences I joined a fencing team, took extensive firearms training and have become a practitioner of Krav Maga. The next time someone tries to hurt an innocent victim in my presence I will be better prepared to stop them.

For those of you within striking distance in such a situation:
* Give no warning, make no threats and do not offer gradually increasing levels of resistance
* Attack with as much horrifying ferocity as you can muster until the attacker is incapable of being a threat

Unless the bad guy is an assassin or a berserk lunatic, he likely has a primary agenda other than murder. He's thinking about stealing, raping, scaring or hurting and the threat of violence is a means to gain compliance. It takes a normal brain a moment to shift from "robbing" mode to "killing", and that is an instant you must exploit if you are to neutralize the threat. If you interject yourself into a dangerous situation you can't afford to play nice or you greatly increase the opportunity for the bad guy to hurt someone.

If you are too far away to strike, start yelling bloody murder and draw attention to what is happening. If the bad guy has a knife, scream "KNIFE! KNIFE! He's got a KNIFE!" at the top of your lungs while throwing whatever is handy at him. This draws attention to the criminal and warns others what specific danger they are facing. Unless he's already bent on murder, chances are good that the attention will make him flee. (Obviously do your yelling and throwing from behind cover if the villain has a gun).

I don't think you really know how you will react in a situation like that until you are actually in it.

That being said, I do not believe that I am capable to tackling a mugger directly especially if the mugger has a gun. I see some of the answers here state that they would run after the mugger and tackle them. I am no hero and getting myself killed would not help the victim.

Helping the victim of a mugging after the fact might be the best way for me to help that person. Whether it is to help the person get to a police station or hospital or to a phone. I would try to help in whatever way that I could.

Some people simply act to stop a mugging but what they fail to realize until it is too late is that by bringing yourself to the mugger's attention, you then become a target. That person could then come after you and your family. It's best to think about your safety and your family's safety first. I know that may sound selfish to some but it is quite simply the reality of the dangerous world that we live in.

It would depend on if it looks like I'm strong or armed enough to overpower the assailant.

Maybe I'd look to see if there's any rocks laying around that I could throw... something ti distract the attacker long enough for the person being mugged to break free and run away.