QUOTE(Dave Chesser @ Jul 20 2008, 11:56 AM)

I was thinking along those same lines, too. But I've been reading Mind over Muscle to try to understand Kano's take on how judo should be performed and how that might differ from my taiji -- if it does -- and I'm a bit confused.
The concept of ju yoku go o seisu that he talks about on pg. 41 seems to be the "soft overcoming the hard" that I would expect of the something called the "gentle way." That seems more like taiji to me.
But then Kano also explicitly says that's not sufficient. Seiryoku zenyo seems to be more inclusive of a broader range of forces in stressing maximum efficiency. So if I'm reading this correctly (a big if), then using muscle in judo would be okay if it was efficient. Or do we always want to rely on technique?
Again, my natural preference is to not use a lot of muscle. But I also want to not just fit judo into my preconceived ideas (or at least try not to).
So is there a little tension between the ideas of ju yoku go o seisu and seiryoku zenyo?
You seem to have assumed that ju means not using any muscle. From what I understand, that is not true.
Say Uke, having gripped you, pushes you back. Instead of pushing Uke back, you go with his momentum, turn your body around and execute o-goshi, while maintaining good balance and body control throughout the process (tai-sabaki). This is an example of
ju yoku go o seisu. You may feel that you have not used any force or any muscle, which is good, because it means you have applied kuzushi on Uke so efficiently. In reality, you must have used some of your muscles to turn your body and enter into the throw (kake). The feeling of not having used any muscle was due to you having used the right muscle groups and not applying excessive force, not because you actually used no muscle.
In Taijichuan too, one must use muscles to move, even if with proper ju. Even at a higher level of skill in Taijichuan, where you would not rely on contracting the muscles of the limbs but instead uses hydraulics (air pressure and fluid pressure) to move the body, you still have to 1) use your diaphragm, which is a muscle; and 2) use certain muscles of your torso and limbs to maintain your frame.
From what I understand,
ju yoku go o seisu is one kind of
seiryoku zenyo, the first core principle of Judo.
It might be interesting to note that Judo's second core principle
jita kyoei is usually not explicitly taught in Taijichuan, at least from my observation and related books. However, a good Taijichuan teacher would talk to you about similar concepts nevertheless, even if it's when for example drinking tea together after a class.
Something else that might be of interest too - the principle
ju yoku go o seisu in Taijichuan is only part of the story. There is also the idea of 積柔成剛 (my rough translation: "integrate
ju into
go"), which is an explicitly taught Taijichuan principle. In Taijichuan 剛
go is essential, just as 柔
ju is. One cannot function without the other - 剛柔相濟 (again my rough translation: "
go and
ju each supports the other"). I think this is also true in Judo, though the common understanding is not necessarily expressed in the same way.