Realistically speaking, I could know a hundred martial arts and yet not be able to defend myself(or others) when needed, because at the end of the day there is no martial art that is "the best" for self-defence.What there are are skills-that you might learn from some martial arts-that will help you defend yourself.
Of course, knowing a fighting style is still better than none, but I don't think that knowing a fighting style means knowing how to fight specially when it comes to those martial arts more geared to sport competition where rules set the conditions and restrictions for a "win".
Let me offer some examples of what I mean:
- Situational awareness
- Positioning
- Able to maintain your cool under stress
What are the abilities necessary in order to be able to actually learn how to defen yourself, and where can a beginner seek to learn about them?