I want to explain the varieties of effects in Tai Chi push hands and kuzushi (more general term for unbalancing work and drills). There are various levels, from grosser to more subtle. Even though I'm using the word 'grosser', I'm not assigning value here. In fact, in real life the 'grosser' work is much more practical for most people for most of their lives. So 'gross' should be understood here more like a value-neutral medical term such as 'gross anatomy', 'gross pathology', 'gross total resection', etc. Strictly value-free, technical talk.
There are at least the following effects in kuzushi which can result in observed movement of another's body (including full uproot effects), ranked from most gross to most subtle. Disclaimer: these are only for use in a life threatening emergency, or a consensual training engagement - AT NO OTHER TIMES:
- Mass differential: This is the most gross in the above sense. Where a big guy can pretty much just pick up a smaller (possibly untrained) guy and body slam him to the pavement. Where you have this advantage, this is by far the simplest, most practical and most effective answer to any close quarter situation. It should be your go-to move whenever possible. Nothing wrong with this, it should always be your first goto move if applicable. There is no "self movement" in this case - whatever happens is directly controlled by you.
- Mechanical leverage: Less gross, it's sometimes possible for a highly skilled and well conditioned smaller guy to use all his stealth, instinct, experience and knowledge to secure a good hold on an opponent and use that to damage him or to escape. This is done with via the normal tools and principles of material objects interacting under gravity etc. against a resisting opponent. To carry this off consistently it's best if you're a natural born kinetic genius like my friend Tim Cartmell, though very hard and smart training can take you some distance. You are applying your physical strength, via some advantageous physical hold or position, to physically cause movemet disruption against his physical resistance. There is no "self movement" in this case - whatever happens is directly controlled by you.
- Startle disruptor: Sensory contact only. An unexpected movement perceived visually, a loud noise from behind (e.g. BOO!) perceived aurally, or an unexpected touch perceived haptically can trigger a startle reaction, in which, with no gross contact at all, his body will move by itself - without you applying physical force or mechanical leverage to it at all. Note that I'm NOT talking here about woo nonsense like so-called 'Empty Force' (凌空勁) which is a whole different (fake) storyline. I'm talking here about normal, reliable, easily observed self-movement via instinctive pre-emption of conscious response. It's a basic survival reflex hangover of some sort.
- Internal triggering: This is an observed movement triggered by "transmission of insufficient physical force" that is, light physical contact used only as a focussing mechanism, coupled with an energetic transfer that causes him to move himself. This is the 'least gross' (least phyical in the sense of gross defined above) and the hardest for people to understand and appreciate. It's hard to understand and appreciate because, unless you've taken this skill totally into the stratosphere like maybe some ancient super masters did, any lesser ability with this effect isn't particularly helpful in 'real' street encounters (see body slams, above). It's too hard to train and takes to long. Nevertheless it's real. And even lesser instructors (like me) can demonstrate this against non compliant partners in a drilll/sportive type of configuration configuration - real enough far as that goes. I described how this works in my book Juice: Radical Taiji Energetics. The energy you apply does not in and of itself move his body! That's the key. You only trigger his reaction as "self movement". It seems very much like the 'startle' thing, but it isn't the same - except maybe at a very abstract level. You are shocking his energy body, his etheric shell, with an unexpected touch, which causes it to 'jump' and it takes his physical meat along with it. But your energy is not mechanical and does not "pick him up" like a tractor beam or anything. The way this works is widely misunderstood by both believers and scoffers alike. But that's understandable, we are all very much keyed into the physical. Again I'm not saying this ability make you into some kind of steely eyed dealer of death on the streets. I'm aware enough of "real fighting" and sparring to know the score. However, I do think this effect is both (a) real and (b) interesting. Fascinating even. It's just fun to play with. As for utility, sure it's not super useful now out on the mean streets (though training this type of energetics does wonders for your power of kinetic pre-conscious awareness - what I call your Automaticity Quotient AQ in my books). I've never claimed otherwise. But it's very interesting, and who know how far it could go? Think of electricity when Ben Franklin was flying kites in lightning storms - who could have known back then what that natural force could be harnessed to do.
Key thing for this post is to understand that the internal power is real on its own terms, that the partner's movement is really non-compliant, not fake, but that your applied energy to him is NOT what's moving him - he's moving himself in reponse to your triggering. As I explained in Juice, it's like an atomic bomb, where the thin neutron beam that's fired into a fissionable mass is not, in and of itself, destroying the city. The destruction comes from the reaction of that fissionable mass (in our case, his innate tension) to the stimulus of the neutron beam. In this way, though it's not an ordinary sensory trick like the bushman prank, on some abstract level the comparison may help understanding.
Come to my Seattle Summer Seminar (details above) to learn more about it.