So, should martial artists seek out street fights in order to prove their effectiveness?
The experience of others counts for something. I trust in the experience of my Master, and what he says will work in the streets, based on his past and credentials. When he says something works in the streets, he's saying from experience. When I say the same thing works in the streets, I'm saying from his experience. Does that make me a con artist and my techniques untested? In my biased opinion, no it does not.
I think there are a few things going on here that we can break down...How can you claim something as personally legitimate, when it came from another's personal experience.
We have two types of knowledge, assumed knowledge and actual knowledge.
Example- I assume that the earth is round, as to available information. But, I have no personal individual experience to say that it is.
If you trust your instructor and his "credentials, and he tells you it does work and has shown that to you...that is still assumed knowledge. Until you yourself test it, it will remain assumed knowledge.
Can a technique work in real life? Under what circumstances? What skills or attributes do you need to make it work? How reliable is it? What evidence do we have to inform the answers to the previous questions?
(Notice I said can it work, not does it work. No technique will work 100% of the time and only an exceptionally bad technique* will fail 100% of the time.)
*(I have been taught a few of those along the way.)
Along the same lines, we can ask can I personally make the technique work in real life? Under what circumstances? How reliably? What details in my execution would make it more or less likely to succeed? Do I even understand al the relevant details? What evidence do I have to support my answers to these questions?
Finally, there's the matter of being open and honest (with ourselves and others) about the answers to the above, including any limits to the evidence we have.
Let me give some examples to make this more concrete ...
Consider the basic rear cross, a staple of boxing and probably a solid majority of striking arts. Can it work? How reliable are the results? Let's look at the evidence.
We have video of literally hundreds of thousands (maybe even millions) of rear crosses being thrown in street fights, boxing matches, karate matches, kickboxing matches, MMA matches, almost every context imaginable. We can see them missing, hitting with minimal damage, hitting with significant damage, and causing knockouts. We can analyze the results based on physical attributes, training, technical details, and more.
We have the collected experience of tens of thousands of professional and amateur fighters who have personally used the rear cross and had it used against them thousands of times.
I think we can be highly confident in our knowledge regarding the general effectiveness of the rear cross. Now, how about my personal understanding of and ability with, the rear cross?
I have used the rear cross in street fights, knocking my opponent down in one instance. I've used it in kickboxing matches, achieving a knockout in one instance. I've used it in sparring (light, medium, and hard contact) with a wide variety of training partners, including boxers, kickboxers, karateka, kung fu practitioners, MMA fighters, and untrained individuals. I've been hit with numerous rear crosses, including shots that didn't phase me at all and others which knocked me down. I've been taught to use the cross by teachers who were successful professional fighters (including one 2x boxing world champion) and whose fights I've seen in person or on video*.
*(Not to denigrate the honesty of anyone's instructor, but there's a difference in the reliability of evidence between "I saw my instructor do this with my own eyes" vs "My instructor told me about this time he did so and so.")
Based on the above, I have a fairly good notion of my ability with the rear cross, but not as good a notion as I would have if I had been in more real fights and/or full contact competition.
Now let's consider something different, standing arm bars (breaks). What is the available evidence regarding these?
We have video evidence of one particular standing straight arm bar (waki gatame) working at least a handful of times in competition. I haven't been able to find examples from a street fight yet, but there may be some out there. I have some anecdotal second or third hand accounts of standing arm locks working in real fights. Some of those are in the context of a bouncer or LEO controlling a noncompliant suspect or belligerent drunk patron rather than in the context of an all-out fight. We have the fact that a wide variety of martial arts with different origins include these techniques. Presumably they were added for some reason, but we don't know the history of how they entered the art or how they were tested.
So we know that at least one form of standing arm lock can work, but we don't have enough data to say a lot about reliability or what it takes to be successful.
What about my personal knowledge? I've been taught a variety of standing straight arm breaks, by instructors who were credentialed in their various arts. I've never used one in a real fight. As far as I know, none of my instructors ever used one in a real fight. I don't know if their instructors or their instructor's instructors ever used one in a real fight. I have occasionally used the threat of the standing arm bar in sparring to force a reaction by my opponent. For reasons discussed in previous posts, I don't attempt the arm bar in sparring with the speed which would be required to prevent an escape. So … maybe I might, in the right circumstances, be able to complete the standing arm bar in a real fight. However I just don't have the evidence to know how likely that would be. I do know that against a competent opponent, even the opportunity to make the threat doesn't come up very often. So if I did have success, it would probably be against an unskilled adversary.
When I teach my students, I try to focus on techniques I have personally been successful with (at least in sparring) and that I have seen others be successful with in real life or in high-level competition. I also try to be open about my personal competence with a technique and the evidence I have for its general applicability.