In Chapter Three of his exquisite book, "The Origins of Virtue: Human Instincts and the Evolution of Cooperation", Matt Ridley recounts the tale of Tosca, the heroine of Puccini's opera of the same name. Faced with the terrible dilemma of her lover Cavaradossi condemned to death by Scarpia, the police chief, she is offered a deal: if Tosca will sleep with Scarpia, he will save her lover's life by telling the firing squad to use blanks. Tosca decides to deceive Scarpia by agreeing to his request, but then stabbing him dead after he has given the order to use blanks. She does so, but Scarpia chose to deceive her too: the firing squad does not use blanks and Cavaradossi dies. Tosca commits suicide and they all end up dead.
Tosca and Scarpia were playing the most famous game in all of game theory: the Prisoner's Dilemma, which applies to any conflict between self-interest and the common good.
