Just curious why you make that statement. I once saw a Tai Chi practitioner demonstrate very effectively how his style and application of Tai Chi made it an effective martial art. He displayed amazing energy.
I said it because of the clumsy and inadequate way I phrased the sentence which is why I also said I hope they know what I mean. I know very well that Tai Chi is an effective martial art but I wanted to convey to the OP that rather than the generally perceived non martial arts idea it is also an effective combative style. As you see that is an even clumsier description.