Humor:

"Humor is similar to emotions in having a strong element of incongruity or change. Both emotions and humor combine two perspectives—the expected and the unexpected. However, whereas in emotions the simultaneous presence of incongruent perspectives is problematic, and hence requires immediate practical action, in humor the incongruity is enjoyable and requires no action. The ability to entertain several different perspectives is typical of humor and moderate positions, and is contrary to the partial nature of emotions. A sense of humor is thus often incompatible with an extreme emotional state. The ability to entertain several alternatives is also a sign of mental health. For example, a person who suffers from paranoia denies that alternatives to his position are possible."

The Subtlety of Emotions, Aaron Ben-Ze'ev, 2001