A little knowledge...

....is a dangerous thing, so the saying goes and this is true when we begin to learn something new.

Consider tennis: the rules are not particularly complicated and there are only a half dozen or so different strokes to use. But if a person had a few tennis lessons and 'learned' the different strokes and the rules in say eight lessons, no-one would expect them to be able to play even a half decent game of tennis.

But I had to catch myself from making the opposite assumption after my first few lessons of Brazilian Jiu Jitsu (BJJ). Having had a few lessons doesn't mean that I am now capable of defending myself. I have 'learned' a few techniques, but I suspect that it will take a long time before they feel natural and I can apply them in a real defensive situation. What has really happened is that I have been exposed to a few techniques that I have yet to master, and which I have yet to learn to apply in conjunction with other techniques I am learning and to apply against someone who is resisting them and strenuously attempting to apply the same techniques to me.

One of the huge advantages of BJJ is that you know the techniques work since you experience them both from the perspective of practising them and from the perspective f having them applied to you. This is quite different from some of the striking arts, such as karate, where you never know whether a punch or a kick would really be effective in an actual self-defence situation since you don't ever have the experience of being on the receiving end of an effective punch or kick. But the danger with BJJ is the danger of thinking that because you know the technique and know it works then it will work for you in a self-defence situation. This is where over-confidence could become dangerous: even knowing how to apply an effective technique, you still need to have a realistic view of your ability to apply it in a real situation.

In Self-insight: roadblocks and detours on the path to knowing thyself, David Dunning mentions the case of driver education in schools and how to the extent that it is linked to accident rates, the tendency is more towards increasing accident rates than reducing them because of over-confidence:

...after Quebec mandated formal driver education, the accident rate among 16- and 17-year-olds went up, not down - causing the mandate to be repealed...One key contributor to this paradox may be that training young drivers in emergency maneuvres gives them a false sense of security. On the day of their training, they, indeed, may know how to control a skid, but their skill atrophies over the time where they might have to use that skill in the future. However, left with the impression that they can handle most, if not all emergency situations, they take chances tey should not take.

Confidence may rise faster than competence, partly because we tend to become more comfortable with something as we become more familiar with it, yet familiarity may have little relationship with actual skill.

I'm not totally opposed to over-confidence: sometimes we can only improve by attempting things that in reality are beyond our current level of competence.

However, where our confidence outstrips our competence in the real world, rather than in a learning situation, it may indeed be a dangerous thing.