In which I probably dive in feet first into an on going argument, because I found an article the other day saying many of the things I'm about to say. But I think they're important things. I've practiced tai chi for years, as well as bagua and xing yi (not to mention plenty of other things, BJJ being the most prominent at the moment), and every so often I go through a phase of looking up tai chi on Youtube. Specifically, I tend to look up things like "tai chi fighting" "tai chi sparring" or even "tai chi MMA". Why? Because I'm of the opinion that tai chi is a martial art, that it should be taught that way, and that people should train it in a way that allows it to function as such.
Yet ninety percent of what I find has nothing to do with combative skill. Most people just don't train that way. Tai chi has become just the practice of the form. Just very elderly people moving very slowly as a kind of exercise. And I've had enough. I have no problem with the idea that tai chi brings health benefits, but classically that has never been its primary aim. The translation of the full name (grand ultimate boxing, or great pole boxing) makes it clear what its practitioners were aiming for. I firmly believe that if you aren't doing a martial art, then you aren't doing real tai chi. You're doing some sort of gentle, arm waving yoga (and you should do yoga, because it's more specifically designed for the health benefits you're looking for).
There are plenty of tai chi classes around me. Of those, perhaps one or two do anything with the applications of the form or with push hands, and most of those see them as advanced things to be gotten to after the completion of the form. Genuine interactive practice is right out of the window, while I suspect that if I had to give you a pound for every time they talked about hitting someone and you had to give me one for every time they made an exaggerated claim about chi or medical benefits, I would end up quite well off. Even at the one "good" club, I felt like we were doing only drilling, with no live practise. Not even push hands.
So I'm going to say what I'm sure a number of people have said over the years. If you're doing tai chi, look at the way you're doing it. I firmly believe that it can be a useful art, if you train it that way. So if you practice tai chi, ask yourself the following things:
Am I just going through the form every session? No one learns to protect themselves by doing forms. No one. Forms are a good way to get repetitions of movements in correctly, but they teach nothing about distance or timing. Nothing about yielding or following. Worse, doing it this way turns tai chi into an external art. It becomes solely about the way things look, rather than about what things really are.
Am I doing my form blindly, or do I understand at least a basic application for every movement? There are plenty of potential applications for every move. Knowing at least one will change the way you do the form, and probably increase its benefits to you. One of my old karate instructors suggested that it should be possible to take at least five different applications from every kata move in that art, including taking the whole thing to the ground, throwing, joint locking, striking and defending. Tai chi is at least that sophisticated.
Are you relying on chi to solve all your problems? There is no good evidence for the existence of chi that I have seen. There is certainly no evidence that it will make you a better fighter. It is not a short cut to easy success. It's a medical model that belongs to the past, and is also far too general to help us understand different nuances. I know, I know, without chi, how can we be an internal art? Yet it is possible to be "internal" without focusing on chi, by thinking about things like the moment of interaction, understanding an opponent, understanding yourself and your structure, the feelings and reactions you bring to an engagement and more. I think that being internal is about letting things flow out from principles of good movement and understanding rather than focussing on the form of the movements. But these things only really develop working with someone else, so it's easier to just talk about chi.
Are you doing some sort of genuinely interactive practice in every session? Push hands is a starting point. I don't think it's the end. I don't think it's an adequate analogue for fighting. But it's a good in between ground, and the bare minimum that you should be doing.
Are you working from principles? There's a tendency for people to look at those who actually fight with soft/internal arts and say "That's not tai chi/aikido/whatever". Actually, it's just not what you're doing. Whatever that is. The movements adapt to whatever the other person is doing, ideally. So long as the core principles of the art are in place, that's fine.
So if you practice tai chi, take a moment to think about what you're doing. If you don't like what you see, change it. Talk to your teacher. Find another teacher. Find a friend who is willing to do some work with you outside of your usual classes. I firmly believe that if enough people work at it, we should be able to put the chuan back into tai chi chuan. I think that it's important that we do.
Anyway, that's my martial arts related rant over for now.