Within the martial arts community, it has become common place to refer to and/or example a person's validity (for whatever they are promoting) via their having a Higher (5th-10th) level of Yudansha (black belt) rank. Presumably, those individuals have been involved with study/training for extended periods of time, and therefore (also) have greater knowledge/experience in whatever it is that they are presenting/teaching.
Particularly within the United States, this is a poor methodology for determining a prospective instructor's knowledge/ability (much less the ability to teach that subject, regardless of the individual's ability).
Rank (in general) is more often purchased than earned. Though understanding that the majority of martial arts are being taught as being a financial income source, thereby making that endeavor and (only) a profit driven entity. Having a higher rank, provides one with (presumed) validity (for whatever they are teaching). By one having a higher rank (than the other person/instructor) one will attract more students (presumably).
Oyata always stated that before you open a school/dojo, have a real job (to earn money to provide for your family). And NO, running a Dojo is not a real job. It can be fun, and even very fulfilling, but a real job doesn't depend on teaching a subject that will be unlikely to fulfill someone's life. Those types of jobs only fulfill a niche/interest of the paying (and teaching) individual.
In America, profit is the worshiped entity. If you can make a profit at doing anything, it's viewed as being productive (?). Anything that doesn't provide a profit, is considered to be a “hobby”. If you're (actually) providing a need, you should (ethically) be doing so for Free. It can also be argued that if/when someone gets something for Free, they don't/won't fully engage themselves in that pursuit.
This is the conundrum that instructors commonly find themselves. Beyond (commercially) “running a Dojo”, the need for achieving a higher rank (beyond Yudansha) is only useful in regards to one's social positioning within the martial arts community (and thereby attracting more students). Though I have interacted with numerous higher level Yudansha, I have considered (very) few of them to be any more/less “knowledgeable” than any of the others that I've met.
Rank, is more commonly being used to compare individual's to one another, rather than being any acknowledgment of knowledge or ability. Higher rank is often associated with longer time having been spent training, learning (and/or doing “something”) that has increased their knowledge level. More often this is not the case.
Rank is far more often purchased. Once a testing fee has been paid, the individual is most likely going to receive that rank. I've seen it so many times, in so many systems/styles and martial art's organizations that I (and most people I've spoken to) have been affiliated with that it has become the accepted standard/norm.
Though awarding higher rank “may” acknowledge some difference in one's knowledge/ability (often only within that specific group of individual's), that rank should not imply any presumed general superiority (of either knowledge or ability).
I've encountered numerous individual's who had impressive levels of knowledge. Rank rarely had any bearing on the validity of that knowledge, or in regards to their ability to apply (or teach) that information. Many of those individual's had only minimal (if any) recognized “ranking” in any system.
My personal interest has always been in the transference (teaching) of knowledge. Not every “skilled” individual is a good/competent instructor. One's personal ability is a separate skill-set (from being able to convey that knowledge/ability to a student). That ability most often comes (only) after having years of (teaching) experience. It's for that reason that I encourage interested parties (student's) to observe and to question an instructor's student's (as to an instructor's competency). That includes my own.
Depending on what it is that you're wanting to learn, the Rank (of the instructor) should be one of the last considerations. The majority of systems require paying (the requisite amount) for whatever rank one deems it necessary to teach (whatever it is that is being shown). Keep in mind that there are NO “industry” standards in this regard (or any other regard for that matter). Personal experience has shown myself, that there are (approximately) 8 low to medium quality instructor's, for every 2 of decent ability to teach (not necessarily perform) some manner of “martial art” (regardless of the “system”). Even in those systems that require some level of performance (of/for the required motions/techniques) for the awarded ranking. Their abilities (or lack thereof) in regards to instruction (teaching) are rarely if ever addressed (much less taught).
Any rank, is only recognized within the individual organization that it was issued in. Every system/methodology/school has different standards, and few (if any) systems are in place to confirm/validate the testing of Yudansha (Black Belt) applicants.
The majority of systems promote the idea that those ranks awarded above (approx.) “5th” degree/level, are “honorary”, and are only representing the amount of time that the individual has devoted to the system. This might be easier to accept (believe?) if those same individual's didn't have multiple (Yudansha) rankings, in multiple systems(?).
IMO, Part of that problem could be rectified by requiring that every person entering a “New/Different” system (from the one they originally received their Yudansha ranking), be required to study that (new) system for 1 (?) year minimum, prior to receiving any ranking (in the new system). Personally, I feel it should only be done for the reception of a Shodan (1st Degree) ranking, regardless of any prior experience. Shodan represents having learned all the basic motions for the system, the assuming of the individual's knowledge (beyond that level), only belittles whatever system/methodology it is that being taught. Despite that (obvious) fact, numerous “instructor's” have (equally) numerous, and often higher rankings, in multiple systems of martial arts(?).
This situation exists in every system that I have ever encountered (either through study within that system, or through speaking/working with individual's within those other systems). Personally, I had 6 years of study within a different system prior to what I now teach, Beyond having learned some basic motions and positions (all of which had to be later changed/modified), I consider that time as having been wasted time (for my study and interests). I don't normally acknowledge it as having “added” to my knowledge level.
When I see the lists of different martial art styles/system's (and “ranks”) that an individual claims to possess, I have to conclude that none of those “systems” were adequate in their instruction (at least for that individual). That being the case, then why include a listing of them? The only logical answer (IMO) is for personal Ego.
The only common “fact” that can be determined by someone having/claiming/promoting the fact that they have a Higher (or any) Yudansha Ranking, is that they have spent money (in regards to now having that rank). The amount of (any) actual “knowledge” (or ability) they may have is more often than not, questionable.
That shouldn't imply that I haven't met some very knowledgeable people. Their ranking meant little to nothing to myself. It was only when they emphasized that ranking, that my (personal) opinion of them evaporated. Though the few that I did feel were (exceptionally) knowledgeable, were (very) few and far between.
Oyata (often) referred to “Higher Rank”(and titles), as well as the various “colored” belts and patches, as lipstick (on a Pig). He didn't concern himself with a student's “rank/title”. All student's were shown (and practiced) the same techniques. Those that were concerned with them, he often (only) made note of. A number of them quit (or managed to get themselves expelled) prior to his death.
Higher Ranking only became vogue after the Japanese began teaching the Okinawan systems (and adopted the dressings of the Japanese systems). Being a member of a (whatever) system shouldn't be the only justification for the awarding of (any) “Higher” ranking. It can (should?) be recognized, but it doesn't (or shouldn't) imply that the person has been (actively) improving/increasing what they know (or how they do it). The only thing being displayed (via a higher rank/title), is the individual's ego.
When asked, I tell people interested in attending a (or any) “self-defense” class, to question (and observe) the instructor's student's (the instructor's personal abilities/knowledge mean little if that knowledge isn't being conveyed). An instructor's Job, is to convey knowledge/ability, not to (only) example their own Rank, which should (only) be noted as a display of the instructor's ego.