Self Defense is a tough subject to teach and discuss. I will try, mainly as a reaction to the misinformation I see.
I will start with the words. Self Defense means to defend yourself. To be your own champion. To be the barrier through which abuse cannot cross. In every sense I have heard the phrase used, this has been the implied definition.
Often when a school teaches self defense, they have a curriculum with some grab counters, a few throws, and assertiveness training. This is okay as far as it goes, however they also convince the student that they (the student) are capabable of defending themselves from a determined attacker. They may be able to defend themselves from a family member or a person who teases, but this is not self defense. Quite frankly you could just move out of the house and a swift kick to the nuts will also stop these people.
Now lets go over the attacker. Who or what is an attacker? An attacker is a creature or group of creatures who wish an objective. These creatures are willing to cause injury and/or death to achieve that objective. This creature/group may have no emotional connection with you (the victim) at all. Any injury received by you (the victim) may hve no impact on the attacker at all.
Lets ask; Who is a victim? The victim is a creature or group which is in a position to lose something and are largely unaware of what connects them to the attacker.
It is possible to have an event with one or more attackers and one or more victims. It is possible to have an event with multiple opposing attackers. It is not possible to have an event with opposing victims. It may be possible to convince yourself of that but you will be lieing to yourself.
In a defense event two opposing attackers are in competition for the safety of the victim. To defend yourself is to take a attacker/victim event and create from it an attacker/attacker event. To do this you must remove the victim.Saying "stop", telling a person they have invaded your space, or striking a dominant pose are all actions which build and maintain a social relationship. They are not how you defend yourself from an attacker. These actions will help in the business world and help in normal social interaction. A physical attack is not a normal social interaction. A rape is not a normal social interaction. A murder, mugging, brawl, etc are not normal. People do not do these things. You do not club your boss from behind to get your check every friday nor do you hold a waitress at knife point to order your eggs over easy.
The Martial Arts were developed for life and death struggles. Quite frankly you do not need iron palm to kill most people. A brick or a handy flight of stairs will suffice. The training of Martial Arts was undertaken by people who were in a situation where they might be murdered for any reason. People were in the habit of solving problems with a well placed knife and the martial arts were supposed to make that concept obsolete. The levels of healing and enlightenment training are examples of how successfull this was.
An understanding developed by martial arts is that training defeats training. There is no mutant human who just understands how to cause pain. All attackers have training. While an attacker may have practiced on children, small animals, or the elderly; it is still training. The knowledge of how to harm another may have come from watching others attack, it may have come from medical books, or it may have come from beating homeless people. The attacker still has knowledge and experience of how to harm others. To pretend that it doesn't matter because it didn't come from a martial arts school is ignorance at its worst.
So as not to die, it is important for the potential victim to know the training of any potential attacker and develop a level of training which goes beyond that.
Training is the biggest factor. If your training was from a teacher who kissed your ass for eight weeks then you probably can't compete with an attacker who may not eat today unless you give up everything of value. If your training was long enough to understand your weeknesses and show you how to compensate for them, then you may have a chance. The standard time span for self defense is three years of hard effort. One year to develop the physical body, one year to train and control the mind, and one year to actually develop the capacity to harm another.
This is another point missed in training. To harm another is to develop a goal which causes the attacker to be unable to continue. This doesn't mean you train to make someone cry out in pain. Most attackers got their start with vengence on those who last made them cry out. It means removing the physical capacity to continue. It means an injury which will cause them to avoid you in the future.
You can't make anyone stop. Are you psychic? Can you delve into their psyche and force them to change their worldview? If you can't then a poke to the eye is your next option. You don't know their pain tolerance or previous training. You don't know motivation or the distance they have already descided to go. Destruction of the physical body is your only option.
When performing a technique you can't hit soemone and then step back. You have to continue. If they don't wan't their arm broken they can pull it back. They can run away, And they can stop attacking. As the victim/attacker you don't have the option to stop the fight. It is not yours. You did not start it and you don't know where it is going. The only way for you to stop the fight is to beat them until they stop and then you continue. When you are finished beating them, you can stop the fight. Since this mental state is pretty extreme and chances are you won't develop it and remain sane, you only option is the first example of causing damage until they can no longer continue. When they are done, they will leave or fall unconsious. Those are their options. Those are the only options you can afford to allow and be safe.
These are things which an eight week course can't teach. Anybody who says they can teach you to stop a killer in under five years is lieing to you and probably themselves. They can only teach you to die, or beat up your drunk uncle. It depends on where you live.