 Here is another story. Bill has a blue cap and would prefer a red one, while Rose has a red cap and would prefer a blue one. Both prefer two caps to any one and either of the caps to no cap at all. They are each given a choice between keeping the cap they have or giving it to the other. This “exchange game” has the same structure as the story about the prisoners. Whether Rose keeps her cap or gives to Bill, Bill is better off keeping his and she is better off if he gives it to her. Whether Bill keeps his cap or gives it to Rose, Rose is better off keeping hers and he is better off if she gives it to him. But both are better off if they exchange caps than if they both keep what they have. The new story suggests that the prisoner's dilemma also occupies a place at the heart of our economic system. It would seem that any market designed to facilitate mutually beneficial exchanges will need to overcome the dilemma or avoid it. 