There is no way to teach someone the exact form that they will have to use to do a given technique "on the street" or in "real life." In the dojo, we practice representative forms of techniques that allow us to talk about strategies and ingrain principles - but these practice forms are just abstractions - they are not likely to be the same as what actually occurs in reality.
So, we have a teaching problem. Do we...
- Teach one form that is sort of an average of the most common situations we think we might encounter?
- Teach 2-3 of the most extreme forms, assuming that the form of reality will be somewhere in the middle of those extremes?
Well, it turns out in aikido, we do some of both.
Take for example, shomenuchi shihonage. We can (among other options) slip inside a right-sided strike and grab the arm from the top with our left hand or from the bottom with our right hand. Which hand predominates determines what the footwork in the rest of the technique looks like, and what direction the final throw happens in. Nearly the entire technical domain of shihonage - everything that can be called shihonage - lies between the left handed form and the right-handed form. These two forms are like brackets that contain most of the forms of shihonage. So, if we practice these two extreme forms of shihonage, then we should be okay whenever we run into a situation that falls within that solution space that is shihonage. This practice of picking a desired form between two known extremes is called interpolation. (BTW - your extremes might not be left and right. Many aikidoka interpolate between omote and ura forms.)
On the other hand, some aikidoka teach shomenuchi shihonage by slipping inside the attack and grabbing with both hands. This is one of the points in the middle of the two extremes, and it is sort of assumed that if you learn this one form, then you should be okay if circumstances force you to vary it either direction (left or right) from the mid-point. You might call this process of coming up with an appropriate variation based on one known reference point, extrapolation.
In our classes (by the way) we use both methods to teach shihonage. We teach both one-handed extreme versions and call them releases #6 and #8, then we teach the two-handed version as the actual shihonage technique in Junana.
It is probably a good idea to look for these three forms (two extremes and one representative middle-form) for each of your techniques. That way you can find your way through jiyuwaza and randori via interpolation or via extrapolation, and you can probably be more assured that you will be able to come up with an appropriate form on the street if you ever have to.
photo courtesy of Angel Medinilla
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Patrick Parker www.mokurendojo.com