Psychiatry is a Pseudoscience

The prefix "pseudo" means: "not genuine but having the appearance of". So if we call psychiatry a pseudoscience then what are we basing it on? First let me refer you to the "Today Show" where a professor from Harvard Medical School said there is no evidence of the existence of the chemical imbalance that is supposed to produce mental disorders such as anxiety disorder, depression, ADD and ADHD. The head of the American Psychiatric Association, Steven Sharfstein, was in disagreement with that statement and said that it was open to discussion. Since when has a scientific fact been "open to discussion"? I thought a science dealt with fact. Can you see two physicists arguing about whether gravity exists or not? I think that is an obvious example of how psychiatry is in truth a pseudoscience. However, if you need more proof then visit this link and read the evidence: Psychiatry is a Pseudoscience