Re: Int. Vs. Ext - resisting a push
I haven’t been contributing much to this thread because I think the whole project is hopeless. This thread is trying to use inadequate physical models to explain how IS works, starting with a statement of the problem that makes it impossible to reach a reasonable conclusion.
Let me justify those assertions, and suggest a model that might get you further.
The physical models are inadequate because they treat the body like a set of stacked blocks (as in Chris’ block man diagrams) and and limit thinking to to “muscles only contract”. Yes, that’s fundamentally true, but the body is so complex it’s irrelevant, practically speaking. Tendons wrap around processes and redirect force. Fascia creates a web of connections so muscle action here can affect the body over there. Parts of the body act like pullys, so a contraction down here can cause something to raise there. Scientists are still arguing about how the body works structurally—I saw a video last year posted by a scientist who had successfully modeled the backbone as a tensegrity structure, with vertebrae suspended in a web of ligaments rather than stacked on each other like blocks. Insisting on a simplistic model of the body will make your inquiry impossible. It’s like trying to study biochemistry using only particle physics—theoretically possible, practically not.
The way the problem has been framed the problem guarantees that it can’t be understood from an IS perspective. The model of the problem people seem to be operating from is that a force comes in, and the receiver resists it (by grounding it, or whatever). High school physics states that if I have a 50-pound push on my chest and I want to stand against it, I need to counter with 50 pounds equal and opposite force. Otherwise, I’m accelerating in one direction or another. Resisting the force, however “efficiently”, turns into bracing yourself against it so it doesn't push you over.
That’s a fundamentally losing proposition, martially speaking. If it’s a 200 pound force, I’ll be crushed however efficient I am. Even if I’m not, I’m pinned in place by that force and my own equal and opposite resistance. I might be totally immoveable, happy as a clam, pround as a peacock—until the guy clocks me with his other hand.
So here’s a better model, equally simplistic but at least it doesn’t point in exactly the wrong direction.
Model the body as a sphere, gimballed so it turns freely in any direction. Any incoming force hits the surface of the sphere. If the force is off-center, even the slightest bit, the sphere turns and the force is deflected. If the force is dead on center, the slightest turn of the sphere moves it off center and deflects it. The force can’t prevent that turning because the surface of the sphere moves perpendicular to the force, so the force can’t counter it. We counter the 50-pound force not by opposing it, but by disrupting it so we never have to deal with it at all.
Stupid experiment to try this out: Shut your eyes and push on a wall at a 45 degree angle. If you open your eyes, you’ll automatically compensate. If you shut your eyes, you’ll feel the wall push you off balance, out into the room.
Some implications of this model:
The receiver is totally mobile and totally free.
The harder the attacker pushes, the more they throw themselves off balance.
Because even a miniscule redirection, or none, is enough, the attacker is offbalanced immediately, with no apparent movement on the receiver’s side.
Turning develops naturally (which it doesn’t in the force/counterforce model), and when you add linear intent, spirals develop naturally. And therefore… Aikido develops naturally.
The reason for Dan’s favorite quote, “Not a fly can alight that does not inducing turning” becomes self-explanatory.
Experientially, this model matches better how using IS actually feels. If I’m doing it right, I don’t feel like Superman holding up 200 pounds—I feel like there’s no push to deal with. It’s irrelevant.
Of course, the model is simplistic. I have to train enough connection into my body so that it can act like a sphere. Not only the body as a whole, but every part of the body, has to be able to act this way. Then there’s layers and layers of details about movement and connection have to be layered on top.
But if you MUST have a simple physical model, maybe this will help.