THE QUESTION OF SANITY
I doubt if a single individual could be found from the whole of mankind free from some form of insanity. The only difference is one of degree.
-- Desiderius Erasmus Praise of Folly, chapter 38
On January 20, 1843, Daniel McNaughton shot and killed the private secretary to the prime minister of England. At the time of the murder, McNaughton suffered from a significant psychological disorder and had been experiencing bizarre delusions for some time. Contemporary behavioral scientists would probably deduce that he had been suffering from a condition known as paranoid schizophrenia at the time that he murdered the private secretary. When McNaughton was tried for his crimes, he was found not guilty by reason of insanity--a benchmark decision that has influenced the Western practice of law since it was handed down. By the standards of the day, the defendant was judged to be incapable of understanding the nature and impact of his actions-- he could not discern right from wrong. Today, the McNaughton test is the most commonly applied standard by which the legal culpability of a defendant is adjudicated. In part, it reads:
To establish a defense on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party was laboring under such a defect of reason, from disease of the mind, as to not know the nature and quality of the act he was doing, or, if he did know it, that he did not know he was doing what was wrong. 1