Delusion (Nancy Kobrin): A delusion is a “belief, idea, or conviction firmly held despite abundant information to the contrary. The partial or complete loss of reality testing is the first indication of a psychotic state or episode. Beliefs, ideas, or convictions shared by other people, members of the same collective, are not, strictly speaking, delusions, although they may be hallmarks of shared psychosis.

Folie à Deux (Nancy Kobrin): The presence of the same or similar delusional ideas in two persons closely associated with one another. Folie: from French folly: madness. From fou: mad. From Latin follere: to move around like a wind, with no direction. à deux: French, à deux: for two. A shared psychosis.

The sharing of delusional (often persecutory) ideas and beliefs by two or more (folie à plusieurs) persons who cohabitate or form a social unit (e.g., a family, a cult, or an organization). 

Extracts above from "The Violent Brutality of Growing Up in A Shame Honor Culture"  Click link on the title to read complete paper.

Scroll down for information on Dr. Kobrin and a description of her book, THE JIHADI DICTIONARY--with information on how to purchase it.