Philip Zimbardo is professor emeritus of psychology at Stanford University and creator of the renowned Stanford Prison Experiment. Daniel Ellsberg served in the Pentagon under Secretary of Defense Robert McNamara and is best known as the whistleblower who released documents known as the Pentagon Papers to the public which detailed the secrets and lies that shaped three decades of American foreign policy in Vietnam.These two icons of progressive thought in America met for the first time to discuss a salient question for our times: Why are some people willing to take courageous nonviolent action in defense of ethical principles, even at personal risk to themselves?