" The troubling aspect of this game, the reason it is infamous, is that it seems clear that each player’s best strategy is always to defect. Whichever pawn is in my hand, you will do better by defecting: if I have cooperated, then defecting will make you £20 richer than you would be by cooperating, and if I have defected then your defecting will spare you a loss of £10. Yet we collectively are punished for our cold rationality, for if we both defect then we are both worse off than if we had both cooperated." http://bosker.wordpress.com/2012/07/23/the-prisoners-dilemma/