information:classification
In popular culture

The comedy movie Hot Lead and Cold Feet has an example of a chain of logic that is collapsed by common knowledge. The Denver Kid tells his allies that Rattlesnake is in town, but that he has “the edge”: “He's here and I know he's here, and he knows I know he's here, but he doesn't know I know he knows I know he's here.”So both protagonists know the main fact (Rattlesnake is here), but it is not “common knowledge”. Note that this is true even if the Kid is wrong: maybe Rattlesnake does know that the Kid knows that he knows that he knows, the chain still breaks because the Kid doesn't know that.Moments later, Rattlesnake confronts the Kid. We see the Kid realizing that his carefully constructed “edge” has collapsed into common knowledge.