In special cases the information can be conveyed. In an artificial game, in which each player’s “value system” is contained on cards or chips, he may simply turn them face up (if the rules permit or if he and his adversary can jointly cheat against the referee). In a society that believes absolutely in a superior power that will punish falsehood when asked to do so and that everybody knows everybody else believes in, “cross my heart and hope to die” is a sufficient formula for conveying truth voluntarily. But these are special cases. If we are to have a “general case” it must be one in which there is at least some ignorance of each other’s value system, or each other’s strategy options, if only because such facts are inherently unknowable or incommunicable.

Thomas C. Schelling, The Strategy of Conflict, loc. 279