A very interesting and revealing discussion.
I think everyone agrees that the application of Yonkyo is possible both with and without the 'pain' that results from pressuring the radial nerve or bone (see my previous posts), and can
be done by focusing or not on this pressure, as the Nage wants, or as the Uke's body type dictates.
My argument is that the basic form of Yonkyo, as developed by the Founder, requires a pressuring of the wrist along with
the un-balancing that occurs through a firm understanding of Ikkyo and Sankyo.
That is what makes it Yonkyo and why it is referred to as 'Tekubi Osae'.
I believe this Yonkyo form (and all the other forms) serves a distinct purpose, since the techniques are all vehicles for teaching principles that can be applied at any time, even out of context (of the technique).
From what people have replied, it looks as though my posts have been interpreted as 'having' to apply pain for this (or any other) technique to work.
It also seems that any time spent finding the pain in a technique is a lovely time for uke to dot your i's and cross your t's.
I would like to clarify again:
I don't think that any time should be spent 'looking for' and/or 'finding' pain.
(Though I know what you mean Jun, when you say that causation of pain is
the focus for many people.)
I have only stated that, in my experience, pain is often a by-product that comes from a correctly executed technique (ie. where there are no openings to escape or counter for the Uke). I totally agree that pain is not the purpose of the technique.
My experience is of course subjective, if that is not your
experience, then that's fine too.