Maudsley bitterly criticized the ambiguous term "moral insanity":
"(It is) a form of mental alienation which has so much the look of vice or crime that many people regard it as an unfounded medical invention (p. 170).
In his book "Die Psychopatischen Minderwertigkeiter", published in 1891, the German doctor J. L. A. Koch tried to improve on the situation by suggesting the phrase "psychopathic inferiority". He limited his diagnosis to people who are not retarded or mentally ill but still display a rigid pattern of misconduct and dysfunction throughout their increasingly disordered lives. In later editions, he replaced "inferiority" with "personality" to avoid sounding judgmental. Hence the "psychopathic personality".
Twenty years of controversy later, the diagnosis found its way into the 8th edition of E. Kraepelin's seminal "Lehrbuch der Psychiatrie" ("Clinical Psychiatry: a textbook for students and physicians"). By that time, it merited a whole lengthy chapter in which Kraepelin suggested six additional types of disturbed personalities: excitable, unstable, eccentric, liar, swindler, and quarrelsome.
Still, the focus was on antisocial behavior. If one's conduct caused inconvenience or suffering or even merely annoyed someone or flaunted the norms of society, one was liable to be diagnosed as "psychopathic".
In his influential books, "The Psychopathic Personality" (9th edition, 1950) and "Clinical Psychopathology" (1959), another German psychiatrist, K. Schneider sought to expand the diagnosis to include people who harm and inconvenience themselves as well as others. Patients who are depressed, socially anxious, excessively shy and insecure were all deemed by him to be "psychopaths" (in another word, abnormal).
This broadening of the definition of psychopathy directly challenged the earlier work of Scottish psychiatrist, Sir David Henderson. In 1939, Henderson published "Psychopathic States", a book that was to become an instant classic. In it, he postulated that, though not mentally subnormal, psychopaths are people who:
"(T)hroughout their lives or from a comparatively early age, have exhibited disorders of conduct of an antisocial or asocial nature, usually of a recurrent episodic type which in many instances have proved difficult to influence by methods of social, penal and medical care or for whom we have no adequate provision of a preventative or curative nature."
But Henderson went a lot further than that and transcended the narrow view of psychopathy (the German school) then prevailing throughout Europe.