Tae Kwon Don't

There is a martial arts food chain, some martial arts are much better than others:

Here's the basic formula to understand:  light contact martial arts < boxing/TKD (any full contact striking sport without knees in the clinch or without kicks to the leg) < kick boxing (any sport with full contact kicks to the leg and knee strikes in the clinch) < grappling < mixed martial arts.

This formula is sound and highly accurate: an MMA guy will typically take out a grappler with no striking, a grappler will typically take kick boxers off their feet quickly, while kick boxers consistently make short work of boxers, who in turn make short work of light contact martial artists.

The problem is it takes time, work, and often money to train in any of these martial arts. Depending on how dangerous an individual's natural instincts are, it's possible light contact martial arts could be worse for self defense purposes than no training at all! However once we get into the realm of full contact martial arts like boxing, training clearly trumps "killer natural instinct."

I categorize Boxing and Tae Kwon Do (as well as "American" kick boxing and Savate) as the least effective full contact martial arts, and suggest they are actually closely related:

• Neither allow significant amounts of fighting in the clinch, depending on the referee to reset the match every time they get too close to each other. 
• Neither allow full contact kicks to the leg with the shin.
• Both are injury prone (TKD practitioners suffer from frequent knee injuries, when boxers fight without glove hand injuries are common.)
• Both are practiced first and foremost for sport and glory, and only secondarily for fitness or self-defense purposes.
• Both tend to use very long stances inappropriate for most kick boxing, MMA sports, and self-defense situations.

Few who practice real kick boxing (with knee strikes and shin-to-leg kicks) ever expect to be famous or bring home trophies, be that sport San Shou, knock-down karate (Kyokushin, Enshin, etc,) Muay Thai or one of several other southeast Asian kick boxing sports:

Kick boxing delivers very efficiently in terms of time, energy, and money on its promise of fitness and self-defense skills. Nothing delivers on the martial arts promise of being able to take on multiple attackers like kick boxing.

More fundamental to any self defense situation however is a fighters grappling abilities:

Not all grappling styles are equal. Judo, once hailed as the only martial art anyone would ever need, becomes so bogged down with new rules every year that some are starting to question its relevance:

However grapplers, unlike previously mentioned martial arts practitioners, are almost always open minded enough to exchange ideas with grapplers from other sports. For example, most Brazillian Jui-Jitsu practitioners have exposure wrestling techniques not normally emphasized in their sport.

Mixed Martial Arts is what happens when grapplers get so open minded that they start adopting kick boxing techniques:

In a nut shell, the more like MMA your martial art is, the better off you will be. This is why when someone says "I have been thinking about doing Tae Kwon Do," I often reply "how about if you just Tae Kwon Don't." See also: http://www.bullshido.net/forums/archive/index.php/t-47730.html