Not necessarily. Ever seen the movie "A Beautiful Mind"? He had no idea his family and friends were figments of a schizophrenic imagination. Just reading about it in a textbook wouldn't have solved his problem, since he had not yet received any information persuading him that anything was fishy.

Edit: But my definition does change how one would go through evaluating whether one was insane. They'd read a book and do what they could to detect anything tricky, like anosognosia or schitzophrenia.

Edit: Once I'm used to commenting, maybe I'll edit less frequently. I apologize to anyone annoyed by this. I decided a more precise way of summarizing my response is a person can still be concerned about whether they have the capabilities to recognize the symptoms.