"Wicked problem" is a phrase originally used in social planning to describe a problem that is difficult or impossible to solve because of incomplete, contradictory, and changing requirements that are often difficult to recognize. Moreover, because of complex interdependencies, the effort to solve one aspect of a wicked problem may reveal or create other problems.
C. West Churchman introduced the concept of wicked problems in a "Guest Editorial" of Management Science (Vol. 14, No. 4, December 1967) by referring to "a recent seminar" by Professor Horst Rittel, and discussing the moral responsibility of Operations Research "to inform the manager in what respect our 'solutions' have failed to tame his wicked problems". Horst Rittel and Melvin M. Webber formally described the concept of wicked problems in a 1973 treatise, contrasting "wicked" problems with relatively "tame," soluble problems in mathematics, chess, or puzzle solving.