When a person is not an adult he is a child.
Tautology is circular reasoning.
Tautology has the form of an answer without any substance.
Why did the chicken cross the road?This says nothing and, as any 6yr-old can tell you, is silly.
Why is Suzy depressed?Same situation as the chicken joke. Circular answer.
We already knew the chicken wanted to get to the other side. That's included in crossing a road. A useful answer might be "to get food" or "to fight off an invader" or "to mate". A useful answer is satisfying. A useless answer is either comical or frustrating. In search of an explanation many people accept "chemical imbalance" as an answer as if it is a cause. Many people are not frustrated by the "chemical imbalance" answer and they don't see it as comical. They have accepted it. They accept the tautology.
Tautology is the act of making a circular answer sound useful.Perhaps you are getting the point and can see to the end.
Why is Suzy depressed?Depression is nature's way of telling you that your struggle has, for a long time, been a losing battle.
There are similar answers for anxiety, schizophrenia, manic-depression, and fighting with your spouse.
Why are they fighting?A useful answer: Stop struggling and start solving.
Why are they fighting?Understanding psychology is understanding the path from infancy to adulthood.