Great post Dave on principles versus techniques.
Kata embodies techniques. Techniques embodies principles.
Principles are the core of the art, techniqes are its shell.
I would be inclined to phrase this differently...
Kata embodies principle. People who don't understand Kata training, the folks who advocate sparring as the only way to develop proper skills for instance, are apt to look at Kata as sterile forms. But if you look at classical kata, they are specifically designed to embody certain principles. Once the practitioner has mastered the principle in that kata, he moves on to other kata which embody other principles or perhaps expand upon the ones done earlier.
At a certain point the practitioner has internalized the principles and the Kata begin to shift. In other words, the kata are not memorized sequences of movements but rather a series of movements embodying various principles. When the principles have been mastered, the practitioner is able to apply the principles generally, allowing his technique to develop out of principle.
Technique, if it is more than just a simple motor skill, is a spontaneous expression of principle. It is created in the instant when principle manifests in an actual encounter.
So principle exists, we use Kata (Forms) to align ourselves with principle, then as we move through the world, this internalized principle manifests as technique.
Now many people do kata, for instance Saotome Sensei has 12 Kumitachi (paired sword forms) which the folks at Nidan need to demonstrate. My experience has been that most folks merely memorize the moves and go through them with a partner without any understanding of the underlying principles.
The result is movements which mimic technique but are not because they are devoid of principle. No one teaches what the underlying principles are and people are generally too unmotivated to discover them for themselves. So in the end there really is no Kata in the true sense because the forms are devoid of principle. Endless repetition of these forms will never yield "technique" merely hollow movement which cannot actually be applied. No amount of mere repetition will yield understanding of the principles at work. One must take each movement of each form and analyze it, look at its variations within the structure of he form to discover the principles governing the movement. Then put the movements into the whole again and look at their relationship, once again investigating the possible variations.
In the koryu with their forms that have been handed down over centuries the forms themselves embody these principles. If one does the forms with an experienced senior partner or teacher, he or she takes the "losing" role and guides the practitioner through the form in such a way that eventually the principles embodied in the form become internalized, often without overt discussion of those principles. They are simply in the form.
But Aikido has no Kata of this type. All of our Kata were made up by our teachers. These are not 500 year old Kata but rather forms created in our lifetimes. Oft times these forms were created to give some structure to what otherwise had none, namely the Founder's sword technique which he never taught systematically. So you have a sort of backwards process taking place whereby certain teachers looked at the techniques O-Sensei did and then tried to construct forms which contained them. Some, like Nishio Sensei, specifically created weapons forms that directly related to empty hand movement. Others, like Saito Sensei adapted whole forms he had done with the Founder that derived from O-Sensei's exposure to classical ryu ha. However, these forms cannot be seen as identical to the classical forms because they are taken out of context and the underlying principles operating are different even though the outer forms are similar.
My point is, that with the sword forms of Aikido, regardless of which teacher's, there is no essential benefit to merely repeating the forms over and over, which is what most people do. The Kata are merely a tool for giving some structure to your training, they have no inherent value in and of themselves. People need to use them to discover principle for themselves. The forms can be changed based on your understanding; in fact I don't think you should be doing them the same at 6th Dan as you were at Shodan. Use the Kata to discover Principle; Principle will then yield technique.
The same thing applies to empty hand but it's harder to see because the practice in Aikido empty hand is less structured than it is with the weapons work. I have actually heard people say that Aikido has no Kata, revealing that they don't understand that our basic training format is all about Kata. However, most folks have trouble with the flexible Form Aikido empty hand takes and attempt to focus on technique rather than principle.
This is one of the main problems with how we train. We are supposed to be discovering the principles of aiki by way of our training. Yet the structure of most classes is anything but aiki. The teacher demonstrates a technique, usually a specific variation of that technique. While the teacher might have been skilled enough for this technique to be executed according to aiki principles, the students are expected to reproduce that technique exactly as the teacher just did it. So they immediately begin to manhandle their partners to look like the outer form of the technique regardless of whether their partner had given them the type of attack, with the proper energy to make that technique the one that flows naturally from the attack. In other words, quite often the uke is giving his partner quite a different energy from what the teacher's partner had given him, but if the student responds by making the adjustment that would naturally flow, he is corrected.
If we are to develop any real skill in aiki we need to be allowed to let the technique become what it needs to, not what we "want" it to. If the teacher wants to teach a very specific principle, then an exercise should be designed which would very narrowly focus on that principle. Often, when I see a student do something different from the way I showed the technique. before I correct them, i do the technique on their partner. Often I discover that the partner is doing something which makes a variation the proper version. Aiki is about connection and letting the energy go where it needs to go based on how you have come together. Either you structure the Form in a way that is very specifically designed to teach a particular principle, such as the forms used in Daito Ryu, or you encourage the students to develop an understanding of principle through "feeling" what the technique needs to be. Years of grabbing and manipulating your partner to make his form conform to the form of the teacher's partner will not yield an understanding of aiki. I know this because that's the way I trained and it didn't yield any understanding of what my teacher was doing. Actually, quite the opposite. I could have kept training for decades the way I was training and I wouldn't have figured it out.
In a given Aikido technique there are many principles functioning simultaneously. It is very difficult, if not impossible, to discover them merely through endless repetitions of waza. When the class is doing waza, there should be the flexibility to allow variation of the technique to occur as the uke changes how he attacks. If the teacher wishes to teach a particular technique in a particular manner, he or she must instruct the ukes how to deliver the type of attack which naturally leads to that technique. Otherwise you have a mat full of people getting all sorts of different variations of an attack and trying to come up with exactly the same result. That is fundamentally not the way to develop aiki skills.
I think we put way too much attention on technique with no understanding of principle. It should be the opposite. We should focus on developing an understanding of principle and then and only then start layering in technical manifestations of those techniques. I think this approach could shorten the learning curve by decades, literally.