Greetings..
Experience is the key.. whether internal or external.. for either to be considered valid, they must have tested their training in situations that closely approximate real combat.. I am always amused whenever we have our local "push meets", a once a month meeting of people from any style/school for pushing, no judges or points, just the experience of testing it.. there are so many players that rely on "rules" to control the experience.. some complain that the action is too fast, or that someone moved their feet too much, or that someone is using too much force.. cripe, that's the purpose, to move toward a combat version of Taiji principles.. it a player finds something they have difficulties dealing with, it's better to find it in friendly play that in actual combat, now you have the opportunity to fix it..
It is extraordinarily difficult to transfer the slow rythmnic movements of Taiji to 70-80% combat speed.. it is equally difficult to deal with 70-80% of the opponent's expressed force compared to the usual 20-30% used in most training scenarios.. but, that is where Taiji SHOULD emerge as the desired discipline.. Taiji is based on the theories of Yin AND Yang.. hard AND soft.. balance.. Certainly, Taiji has a difference in its expression of hard Jing as compared to an external expression.. but it IS hard jing and if it's not trained to the point that it is internalized, it will not easily manifest when it's actually needed.. Listening, adhering, sticking, following is not an easy task at 80% combat action.. it requires much testing at that level..
One observable difference between internal and external is the level of control.. external, generally, has an approach of total domination and destruction.. the intention is clear and definable.. internal, generally, matches the opponent's speed/force and generates controlling techniques, adding just enough to control the situation.. relaxed and deceptive.. Cultivating a practical understanding of balance, alignment, force vectors, and "human nature" is a key component of internal dynamics.. training to the point that your movements are smooth, relaxed and natural conceals the application and the potential of those movements.. one of my mentors moves with such grace that i seldom sense the urgency needed to counter his applications, there is no apparent threat until it's too late..
Whole-body movements without extensions of arms or hardness in the hands is difficult to discern as threatening, and.. as my legs and waist support the relaxed upper body, the opponent feels no need to make quick defensive adjustments.. and, if i am sufficiently skilled, when the opponent realizes the threat, it is their reaction to it that completes the technique.. THEY give the application its power, i just set it up.. Where an external player seeks to destroy the opponents guard and defenses, an internal player knows that the same guard and defense gives the opponent a sense of security, we tend to leave it in place and use it to our advantage..
If you were to hold your body rigidly straight and fall forward, do you reach out an hit the floor to control the impact? No, you reach out and bring the floor to you in a controlled use of Peng.. this a basic difference of internal vs, external.. external hits, internal applies controlled force.. If you jump off a 5 ft. high wall do you stiffen the legs for impact, no.. you absorb the force in a controlled folding of the legs.. Peng.. Your hands are like the bumper of an auto, they manifest great power without moving out ahead of the auto.. they are powered by a good engine (energy) and its relationship through the wheels (feet) to the ground.. the steering wheel is like the waist, directing the hands.. and the driver is the mind that controls it all.. when you push an auto do you fix the legs and torso, pushing only with the arms and hands?.. no, it is an integrated whole body effort.. many of my classes spend some time pushing on a wall, if a line between the heels is parallel to the wall an "arm" push will move the pusher backward.. but, pushing with the legs and torso while keeping the arms in the same spatial relationship to the body will generate much force with little effort.. and, opposite reaction force is directed downward, further stabilizing the rooting.. this is a great exercise for self-evaluation...
Be well..
TaiChiBob.. "the teacher that is not also a student is neither"