Five great revolutions have shaped political culture over the past 50 years, says theorist Ivan Krastev. He shows how each step forward -- from the cultural revolution of the '60s to recent revelations in the field of neuroscience -- has also helped erode trust in the tools of democracy. As he says, "What went right is also what went wrong." Can democracy survive?

What does it mean to be a libertarian? Dr. Jeffrey Miron at Harvard offers one answer. According to Miron, libertarians have enormous respect for individual decisions. While other ideologies attempt to use government force to advance their ideas of how people should act or behave, libertarians think that individuals should be able to live their own lives as they see fit.