This is one of the things that drives me *CRAZY* about Aikido. Here you see *one* art that's only 60-80 years old (heck, we can't even agree on that!) and we can't even have a discussion about it using terms that we all understand. Yet in the past when I've tried to elicit a discussion about what it actually is, everyone poo-poos it like some absurd question because anyone who actually studies the art would know it immediately.
Honestly, in the JSA communities, you just don't see this. I've had conversations with people from dozens of different ryu-ha ranging from 20-400 years in age and we all manage to understand what the other is talking about. Sure you get lots of, "Ah, I see what you're doing, we don't do that." or "Aha, we call that X not Y." But here in Aikido, this amazing unifying art, we can't even agree on what the @#$% word Aikido means.
Chris, I've come to the conclusion that this is a pedagogical issue, going back to Ueshiba Morihei, and perhaps even to Takeda Sokaku.
In JSA, whether it's kendo or koryu, there's a progression. You learn A, then you learn B, and then C. And your progress is monitored by someone who has gone through all these steps, and most likely, all of the steps there are in the particular art. Through this guidance everyone develops roughly the same foundational knowledge, which is then built on and developed to express each particular art's over-encompassing philosophy of interaction.
But what did Takeda do? He simply showed waza, and the students were expected to "steal" the technique. Ueshiba just showed waza, and the students were expected to steal the technique. Certainly there's "stealing" and self-exploration in JSA, but it's still within the structure of the progessive curricula.
I think it's interesting that just about every student of Ueshiba felt that they couldn't teach their students the way Ueshiba taught his. And they all created their own, diverse pedagogies for teaching aikido, each colored by their own experiences and understanding. And their students, in turn, experiment and explore, and create their own
methods of teaching, some at a relatively low level. You have in aikido many, many teachers who haven't reached an understanding of "aiki", who are still seeking that understanding, rather than refining it. Yet, they have their own dojos and are teaching. And all this gets furthered colored by how "martial" they expect their aikido to be, how philosophical, how much it conditions "ki", and so on. Ueshiba made the statement that atemi is a vital part of aikido, and yet everyone in aikido has to explore on their own how to integrate atemi into their aikido. There's no foundational knowledge for that found in the Ueshiba line of aikido.