Re: Principles of pinning
Nice comments and thoughts. I respect anyone who thinks this deeply about Aikido.
I don't 100% agree with everything you say but none-the-less very interesting.
Something I've been doing a bit of is teaching people the bits beyond pinning. That is moving from a pin to a submission. I consider an Aikido pin a point that has a measure of discomfort, even some pain, but if the person resists it makes it worse, and in the dojo, can lead to the tap.
Aikido appears to have somewhat a lack of pins, as they often don't work (when a person puts up a little resistance), the person moves out of it to a new position and the Aikido exponent is left scrambling. I'd like to see teachers concentrating more on a range of alternative pins for your partners reactions.
Or you can forget all that, and be really non-aikido and just go straight for the submission.