Is Jeet Kune Do just a philosophy? Is a sport (football, basketball, soccer, hockey) just a rule book?
No!
The philosophies in JKD are as important as the rules in any sport. And just like those sporting rules, these philosophies guide the physical actions in an environment.
Taking that further, these philosophies are coupled with drills and movements that cultivate desired attributes of those performing inside of those environments.
Just like a coach might do various drills to cultivate a type of player within a sport, you are cultivating a type of fighter within JKD. Both have movements that are guided by their "rule book", one by sporting rules and the other by philosophies.
Whether it is a game or a fight, those involved will be best served by performing in the moment. Being present and reacting accordingly to each moment. This takes practice. Lots of it.
So whether you are reacting to an opponent in a game to score a goal or against an opponent on the street to score a hit, you are reacting in the moment based on your training.
That training is dictated by the rules or philosophies by which you cultivate yourself.
The problem is when you mix them. The rules of tennis aren’t the same as the rules for basketball or soccer.
This doesn’t mean that certain drills found in one can’t work to develop an athlete in another sport. Coaches the world over will borrow training drills from other sports to help their athletes perform better. The training becomes an issue when the athlete begins to react in a sport specific way that is counter to their chosen sport. Looking at basketball and soccer, we can see where many skills could cross over. Running and lateral movement are used heavily in both. Drills to help with this would often work for athletes in both sports. However, if we get into how an athlete trains with a ball, we get very different and contrasting rules. For an athlete, this becomes an issue at some point in their training, because they are applying the wrong skills to their sport. They’re breaking the rules. Can you kick a basketball or dribble a soccer ball? Of course you can. Just not in games, the environment for those sports. So the drills to develop those athletes must diverge at some point.
The same is true when you step out of sport and into combative approaches. JKD seeks to hit, be efficient, simplify, and utilize the longest available weapon to the nearest available target. The drilling, or physical practice, of JKD is always guided by these philosophies, these rules.
Will it be a loss if you break from this philosophy? Maybe.
Let's look at our sport example. In a game, the penalty might be slight or it could be at a critical moment. Or worse, a series of penalties for breaking the rules would counter all of the gains made by a player or team. How many games or matches have we seen lost because of too many penalties? Especially in a close game! When both teams are equally matched in all ways, a single penalty by either means a loss!!
That’s what the thought process is for cultivating in Jeet Kune Do. No penalties, or in the case of JKD, no passive moves. Everything needs to be a hit. The saying in JKD is "the first one to go passive loses."
Bruce Lee streamlined his personal movements. Yes, he looked at other martial arts. But he didn’t cultivate those arts. Or in the case of Wing Chun, he began cultivating differently. Did he take drills from other arts? Absolutely. Then he modified them to fit in with his philosophical approach to combat, his rule book. JKD is his drilling, his practice, for the cultivation of attributes through physical means that are guided by the philosophies he thought best suited to the environment of hand-to-hand, street combat.
The same can be said of Karate, Aikido, Wing Chun, or any other martial art. Their movements and drilling are guided by their own philosophies, their own rules, to help an individual perform to their utmost in the environment for which they cultivated their skill set.
Here’s the big thing to keep in mind. Some cross training can be really great. A fresh perspective or new drill can give some much wanted inspiration. Moving with someone else will definitely challenge your own understanding of movement. How does your attack work against different opponents? How must you "fit in" to their movements in order to score?
But drilling too long under the guidance of different rules, different philosophies, will ultimately take away from peak performance in your chosen environment. Imagine picking up a soccer ball (when you're not the goalie) at a key moment in a game, or kicking a basketball.
Cross training in boxing would be a great to challenge certain aspects of timing and distancing. Yet, again, it is a different environment. A boxer will move differently in the chosen environment of hand-to-hand, street combat than a JKD cultivator would. The same can be said for a JKD cultivator in a boxing ring! How many times do you think a JKD cultivator would break boxing rules? Lots!
This is under the assumption that they were performing at their utmost, forced to use everything they had to overcome their opponent. A kick to the leg, a knee to the groin, still hitting them when the opponent is down, not breaking from a clench….you see how it’s not following the boxing rules. The boxer might be relying on the added protection of a glove to defend on the street or automatically stop fighting and back off if an opponent goes down. Or put zero defence against a kick to the leg. Or the groin!
A big difference is that boxing is a sport. If you break the rules, you could get disqualified and the bout would end. In a street scenario, if you break the rules you might get beat up, seriously injured, or killed.
This also applies to why it’s called Jeet Kune Do and not Wing Chun. Because the movements and philosophies are different. Despite the chosen environment being the same. They are not the same art. Kind of explains the name change. The whole "no passive moves" thing was a major divergence from Wing Chun. It goes both ways though. JKD is not Wing Chun, because JKD does not follow the rule book or Wing Chun.
I'm not against Wing Chun. I'm not against any martial art or sport. I'm just pointing out that they are different. If you are cultivating using Jeet Kune Do, you need to cultivate using Jeet Kune Do. Not something else.
Doing a mixture of other martial arts and calling it Jeet Kune Do is silly when you actually look at it. You wouldn't practice basketball, soccer, and volleyball and the call it football. Why would you put a jumble of other martial arts together and call it JKD? Especially sport arts?! They aren't even in the same environment, or playing field. Think of playing basketball on a hockey rink!
There could be a reason for the confusion though.
It is widely known that Bruce Lee was influenced by other martial arts. All martial artists are, but JKD is often quoted (I think accurately) as being a mixture of modified Wing Chun, modified western boxing, and modified western fencing. "Modified" is the key word here. What were the modifications? To find out, you could explore each of those arts. I've been around each of them to some extent. Wing Chun is very different. Boxing is a sport, although there are some great drills to help mid-level JKD students work timing and distancing safely. I've taken fencing, and what Bruce Lee took from fencing is not what most people think. However, you must have something to compare it to! If you have never trained in Jeet Kune Do, there is no way you could compare it to any other art. If you're training in those arts to get to JKD, you'll never arrive. It's like playing tennis every day and thinking you'll join the NBA.
Jeet Kune Do isn't a jumbled mix of other martial arts; it is its own entity. It has its own rule book.
However, there are many ways that you can (and I would even say that you should) train with people from other arts. Working hands with a boxer, locks with a BJJ person, throws with a Judo person, take downs with a wrestler, kicks with a Tae Kwon Do person, punch/kick with a Savate person, and knees/elbows with a Muay Thai person. You could do some sparring with an MMA person. You could equally play some basketball, or football, or hockey with athletes from those sports. These would all give you some insight on movement. But you should be a JKD person moving with another martial artist or athlete. They will learn and grow from you as well. That's how it should be.
It goes back to application. It isn't just that you can move. Can you move according to the "rule book", the philosophies? And do it in the environment of a hand-to-hand combat on the street against an opponent who forces you to use everything you have? Any movements or knowledge taken from another art must be translated into something applicable in the world of JKD. If you can not do this, then it isn't JKD. That doesn't make it useless or unwanted to you as an individual. It does, however, go against the JKD "rule book".
Cultivate the skills and reactions of Jeet Kune Do, then challenge those skills and reactions against other martial artists or sport athletes, so that you may continue to learn, grow, and evolve.
When you cultivate, you look at the rule book, so that when you must apply you don't need to.