Being Double Weighted

I have said that I would write about double weighting in Taijiquan push hands (tuishou). I probably need to do a whole article but I just picked up a copy of Erle Montaigue's Power Taiji (Paladin Press 1995). Here is his website, and he has a live webcam form correction service. I'm impressed.Erle Montaigue
Here is a quote from the book:

8) "If you think that your push-hands is good and you pride yourself on not being able to be pushed over, start from the beginning again because you have not learned taijiquan. You must use this exercise to help each other to understand some very important principles of taiji. If it becomes a competition, then you are only learning push-hands and not taijiquan."

Double weighting can have many meanings, but here he is referring to a kind of defensiveness that can develop from improper practice.
This defensiveness is both physical and psychological. At the physical level I sometimes call it “defending the middle.� One can actually get good at not being pushed by sinking in between ones feet, hunkering down, and then letting the upper body and the head move freely around. This is a big mistake because you can delude yourself that you are getting good, you can convince yourself that you are winning. In reality your opponent has to ‘up the ante’ if they want to win, and if they are nice they won’t.

There are four primary push-hands movements: peng, ji, lu, an.
If you stay with these movements your practice will improve. There are also four secondary push-hands movements: cai, kao, lei, zhou. When your partner makes a mistake and leaves peng, ji, lu, an, you must respond immediately with cai, kao, lei, or zhou. The problem is that if your partner responds quickly, so must you. Zhou, for instance means use the elbow to pivot, throw or strike. In slow motion, that’s fine, but moving fast you risk really hurting your partner. Nice people will just lose.
Someone who has taken this wrong path is very difficult to convince they have made a mistake. Usually they will be convinced that they are superior to you.
If my readers want, I will link to Youtube videos of people practicing “defending the middle.�
Since this a totally new blog. I await your responses.