Anyone who says that full squats are “bad for the knees” has, with that statement, demonstrated conclusively that they are not entitled to an opinion about the matter. People who know nothing about a topic, especially a very technical one that requires specific training, knowledge, and experience, are not due an opinion about that topic and are better served by being quiet when it is asked about or discussed. For example, when brain surgery, or string theory, or the NFL draft, or women’s dress sizes, or white wine is being discussed, I remain quiet, odd though that may seem. But seldom is this the case when orthopedic surgeons, athletic trainers, physical therapists, or nurses are asked about full squats. — Mark Rippetoe