Several paragraphs in the author makes an important distinction:
Unfortunately, those disciplines are also where most critical thinking instruction supposedly occurs in our universities. (Actually, other fields, such as the hard sciences and engineering, probably do a better job of teaching true thinking skills—compiling and evaluating evidence, formulating hypotheses based on that evidence, testing those hypotheses for accuracy before arriving at firm conclusions. They just don’t brag about it as much.)
Another example of the rule of thumb that those who talk a lot can't do much while those who do a lot don't talk much.