In World War Z, one of the characters described something called "the tenth man rule."
After several disasters that NO ONE thought could happen, the Council decided that if a vote was unanimous against a possible outcome, one member would act as if it was ABSOLUTELY going to happen, and trying to prevent it. This way, if they have a crisis, one man is prepared for it, and assumes directorship of the council for the duration of the crisis.
It sounds familiar to me, but I can't place it...
Does this have any basis in fact/policy in any real government, or was this a pure fabrication? If it's purely fictional, has this concept been used in other works?