I really don't think it is very scientific, going by my own experience and all the people I have met, with their ever-changing diagnoses. Maybe 10% science, 30% intuition, 30% guesswork, 30% fantasy. (I did start out with a lot of respect for psychiatry. Disillusioned.)

What gets me is that when it is so unscientific they are prepared to impose all kinds of decisions on people without worrying about the consequences. They are so sure they are right.