In planning and policy, a wicked problem is a problem that is difficult or impossible to solve because of incomplete, contradictory, and changing requirements that are often difficult to recognize. It refers to an idea or problem that cannot be fixed, where there is no single solution to the problem; and "wicked" denotes resistance to resolution, rather than evil. Another definition is "a problem whose social complexity means that it has no determinable stopping point". Moreover, because of complex interdependencies, the effort to solve one aspect of a wicked problem may reveal or create other problems. Due to their complexity, wicked problems are often characterized by organized irresponsibility. The phrase was originally used in social planning. Its modern sense was introduced in 1967 by C. West Churchman in a guest editorial Churchman wrote in the journal Management Science, either repeating his own coinage or responding to a previous use of the term by Horst Rittel—the origin is uncertain. Churchman discussed the moral responsibility of operations research "to inform the manager in what respect our 'solutions' have failed to tame his wicked problems." 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. Characteristics Rittel and Webber's 1973 formulation of wicked problems in social policy planning specified ten characteristics: There is no definitive formulation of a wicked problem. Wicked problems have no stopping rule. Solutions to wicked problems are not true-or-false, but better or worse. There is no immediate and no ultimate test of a solution to a wicked problem. Every solution to a wicked problem is a "one-shot operation"; because there is no opportunity to learn by trial and error, every attempt counts significantly. Wicked problems do not have an enumerable (or an exhaustively describable) set of potential solutions, nor is there a well-described set of permissible operations that may be incorporated into the plan. Every wicked problem is essentially unique. Every wicked problem can be considered to be a symptom of another problem. The existence of a discrepancy representing a wicked problem can be explained in numerous ways. The choice of explanation determines the nature of the problem's resolution. The social planner has no right to be wrong (i.e., planners are liable for the consequences of the actions they generate). Conklin later generalized the concept of problem wickedness to