Here are some great thoughts from healer/taiji practitioner Philomena Papirnik (who is every bit as musical and magical as the name suggests).

What is the use of resistance? How do we use it in taiji? Where is the strength in being resistant?
Or is that not possible.

Is resistance the I-It equivalent of the I-You of ‘meeting’, (in so far that it’s fragmentary perhaps?) and that it objectifies?

I’ve been thinking I’ve been meeting but yet again, I haven’t. I’ve been resisting some of the time. Meeting’s not just a feeling, is it? It’s everything rolled up into one moment with a million zillion parts. It’s all the port-holes wide open and trusting what’s coming and letting it be what it be. My word…

Resisting is much easier because we can engage muscles and frown and think we’re doing something and winning and staying ahead and not being found out or seen through. There’s a sense of force, strength, power; a security in my head as opposed to trusting that feeling of meeting the pressure and presence of the big chi and using that resistance as an entry-way into another port-hole.

Meeting is wide open and free and vulnerable and open to the elements.

Resistance is all the eyes of your body closed but your muscles gripping at every joint and putting effort into moving as far away from the earth as possible.
–Philomena Papirnik

Thanks Philomena. You nailed it. Warnings against resistance in the literature go back at least to the Yang Family Forty Chapters, but I’ve never seen it stated quite as eloquently as you just did.
I have written elsewhere that Fear resists What-Is and Love embraces What-Is.

I think that fits with what you wrote. We resist when a form we value seems to be threatened by something else. That can be my body, an opinion or belief, or an emotional state.

If I’m playing push hands and someone gives me a hard shove, that will often trigger a resistance in my body. Particularly if it is perceived as a threat. My tendon guard reflex (a primitive stress response) kicks in, and my muscles tighten, my joints lock, and I dig in. Perfectly natural, eye-of-flesh response. It’s hard-wired into the system.

It’s a typical reaction, but not a taijiquan response. It’s not very sophisticated and doesn’t allow for much discernment. Like slamming on the brakes any time you get confused while driving a car. You do it often and everyone gets a little edgy. Also, it’s not very effective.

The taijiquan response is, as you suggest, to meet the incoming force openly and consciously. You engage the whole being with your whole being. It is not Joe’s arm that is shoving me. Joe is giving me an energetic communication that I welcome as an extension of his whole being. Rather than close down and resist his communication, I embrace it and return an appropriate energy to him. Paradoxically, I am more alert, powerful, rooted and resilient than in resistance mode. This takes some getting used to since it flies in the face of patterns we’ve seen and used forever.

As you say, “Meeting’s not just with the eyes or the heart or the hands or the feet or the kua or the mind … it’s everything. It’s the whole.”

In those moments we resonate with the Dao.