I am anti-fajin 發勁 or fajing 發精 (depending on the character, most people use the jin 勁 character, but that is another blog post).
Why am I so anti-fajin?
Fajin is defined here as shoving, but it is using magic tricks to shove, so we might call it competitive-deceptive shoving, or technically-superior shoving.
If you do it entirely without uprooting it is just a tackle, it's physics, mass times velocity squared (MV2). Nothing wrong with that.
If you shove someone from behind by surprise, most people will stumble a few feet and recover. This is an amazing phenomena. Why is this? Why are humans so incredibly good at instantly regaining balance? Obviously we evolved this way. I believe we are constantly practicing this skill unconsciously. Can we practice something unconsciously? We usually call that "conditioning," but I think this is a special case. Anyway, I don't know, but re-balancing and re-orientation have been studied a lot by the field of kinesiology.
But fajin is almost always face to face, making it a part of the Monkey Dance. The push-hands game is the most common way people come to understand fajin, and it comes with the concept of uprooting. What does that mean? and how is uprooting different from simply unbalancing ones opponent?
Perhaps uprooting is unbalancing a person in a way that makes them conscious that they are being unbalanced. In other words, it is a type of dominance display. A person who is aware they are being unbalanced and anticipates being shoved, will make their body rigid so that they can maintain their body's single unit structure while they jump or stumble backwards to regain balance. (Isn't it amazing that people can recover balance so easily?)
If you unbalance someone and instead of shoving them you move your arms in towards their body (like a punch or a slap for instance) most people will sacrifice their structure and even their upright orientation to avoid being hit while they are off balance. From a fighting point of view, this is a far superior result to shoving them. And it makes it harder for them to hit you back.
If you unbalance someone and wait until you feel their force on your own structure, or their center of mass, it is too late. Once you feel them, you no longer have access to this effect. Moving your arms in towards their body will no longer cause them to give up their structure because the simple aggressive act of "feeling them" will signal to them what you are doing. They will turn, or block, or brace themselves, or step out of the way, or try to hit you at the same time. You'll have to start the unbalancing over again.
You can probably see now how push-hands can be used to condition terrible habits. Fajin has some value, everyone should know how it works, but it isn't a very important part of practice. The only non-Monkey Dance fighting situations were it is a good idea is when there is something dangerous to push the threat into--like a bus, or off a bridge.
Anyway, waiting until an opponent is rigid before pushing them isn't a great martial strategy, especially for multiple opponents. Usually you don't want them to come running back at you after they recover their balance. Tricking your opponent into being rigid, has lots of other martial applications that are a better use of time than practicing fajin. And messing up their structure is often a better choice.
But none of that would make me anit-fajin! That stuff is just a minor annoyance and can all be debated until the cows come home.
The reason I'm against fajin is because people associate it with the internal martial arts. If someone believes this lie, there is almost no way to explain to them what internal martial arts are. It is like a blackhole that sucks all the intelligence out of people.
Because the simplest and most direct way to describe internal martial arts is that no force goes out from the body. It is non-aggressive in this very weird way. Internal means that we always maintain whole-body unit force, we never use force that comes out from the body. If you issue force out from the body, its called external martial arts. It also works, but it doesn't work with the Daoist golden elixir practice (jindan).
When you practice the golden elixir and martial arts together, you are always touching your opponent with the lightness of a feather. Even when you do a heavy chop that breaks their structure and takes them to the ground, all contact feels light as a feather. That feeling is also a consequence of never going force against force.
In the language of Daoism, if the body leaves the qi egg, it has become external. However, if you always fight into emptiness, you will being doing internal martial arts automatically. Aren't human beings amazing?