In 1987, E.D. Hirsch sparked a national debate with his book "Cultural Literacy," claiming that there is a foundation of common knowledge every American should know - and codifying it in a list of 5,000 facts and cultural references. Today, amidst giant demographic and social shifts, the United States needs such common knowledge more than ever. But a 21st century sense of cultural literacy has to be radically more diverse and inclusive. And it needs to come not from one person but from all of us. Eric Liu, executive director of the Aspen Institute Citizen and American Identity Program, asks Anne-Marie Slaughter (president of New America), Jose Antonio Vargas (Pulitzer Prize-winning author), and Hirsh what they think it means to be American.