"You fight how you train, you train slow movements and not against a resisting opponent... you think your gonna learn to defend yourself?
You may argue that it takes a long time to learn to defend yourself with tai chi... maybe... what if you need to defend yourself now and not 50 years from now when youve mastered tai chi?
-Ben"
OK Ben. First, you should do a little reading on the subject of Tai Chi. I'll help you out on this though. If you had read my post you would have noticed that I said "...Why is Tai Chi done so slowly? Because it is teaching the student to develop and manipulate large amounts of energy so that when they are done with speed on an opponent they send him flying to the ground." The forms of Tai Chi are done slowly. They are done slowly in order to learn how to generate large amounts of energy, and to train the entire body to be relaxed and fluid etc etc etc. Most Chinese systems use a type of energy in their stikes and movements called Jing (sp?). Bruce Lee said it best by stating that it's like a chain with a metal ball at the end. Think of how that works and you'll understand how a system like Tai Chin functions. So...the forms and movements are done slowly as explained above so that when it comes time to act the movements are fast, explosive, and very powerful.
Next. Tai Chi DOES train against a resisting opponent IF one finds a legitimte school. There are Push Hands drills, applications against punches, kicks, grabs, etc. I have personally seen demos by my own Sifu who taught me Wing Chun, and who teaches the Yang Short Form of Tai Chi. I also visited a school of the Chen Ming branch of Tai Chi and straight up asked a senior student to defend against some basic attacks. I threw basic strikes like jabs and hooks etc and the guy was a GHOST. I got hit rappidly about 3 times , and sent to the ground each time. When I lunged in to hit him he was gone, and I was on the ground. I guess you could go to that school and tell him that Tai Chi is not really about combat. Come down to Dallas and look up Authentic Kung Fu in Fort Worth, or the Chen Ming guys in Plano.
So...with all of this being said. One has to find the RIGHT school that teaches a Tai Chi that still has its teeth. It does not take "50 years" to be able to defend yourself with Tai Chi if you have the right instructor AND the right frame of mind. But, Tai Chi is not only about fighting so if one is looking for a system that teaches self defense immediately then they need to look into a less complex system.