America's unmet challenges are huge: from energy policy to nuclear weapons, climate, health care (yes, still), a sagging infrastructure and a soaring deficit. Yet every one of them is eminently solvable. The answers are well known. So what explains, for example, thirty-five years of inaction on energy policy and even longer on health care? Why do we still approach nuclear weapons as though the Cold War continues when it ended 20 years ago? Is the policy gridlock that afflicts us the symptom of a vibrant and engaged - if polarized - society? Dr. Jessica Tuchman Mathews, President of the Carnegie Endowment for International Peace addresses these critical issues in the 2010 Citi Foundation lecture.