Sunstein has written a new book, called “On Liberalism,” which is a defense of the idea of liberalism at a time when Sunstein believes it is under threat from both the right and the left. You have chosen to write a book about liberalism at a time when liberalism is under threat without really talking about what those threats are. What liberalism are you talking about in the book? This is not liberalism of the left, and not liberalism of the neoliberal sort associated with a particular set of right-wing views, but instead a commitment to freedom, pluralism, and the rule of law. I almost called the book “Big-Tent Liberalism,” which means a form of liberalism that includes Ronald Reagan and Barack Obama, and that includes Mill and Robert Nozick, who was a libertarian.