Psychology is more an art form than a science. There is no “Theory of Everything” from which one can derive all mental health phenomena and make falsifiable predictions. Still, as far as personality disorders are concerned, it is easy to discern common features. Most personality disorders share a set of symptoms (as reported by the patient) and signs (as observed by the mental health practitioner).
Patients suffering from personality disorders have these things in common:
They are persistent, relentless, stubborn, and insistent (except those suffering from the Schizoid or the Avoidant Personality Disorders).
They feel entitled to – and vociferously demand – preferential treatment and privileged access to resources and personnel. They often complain about multiple symptoms. They get involved in “power plays” with authority figures (such as physicians, therapists, nurses, social workers, bosses, and bureaucrats) and rarely obey instructions or observe rules of conduct and procedure.
They hold themselves to be superior to others or, at the very least, unique. Many personality disorders involve an inflated...