Humanity's main concerns today are not so much concrete evils as indeterminate threats. We are not worried by visible dangers, but by vague ones that could strike when least expected — and against which we are insufficiently protected. There are specific, identifiable dangers, but what worries us most about terrorism, for example, is its unpredictable nature.
What is most disturbing about the economy these days is its volatility — in other words, the inability of our institutions to protect us from extreme financial uncertainty. Generally, much of our uneasiness reflects our exposure to threats that we can only partly control.
Our ancestors lived in a more dangerous but less risky environment. They endured a degree of poverty that would be intolerable to those in advanced countries today, while we are exposed to risks whose nature, though hard for us to understand, would be literally inconceivable to them. Because interdependence exposes everyone around the world in an unprecedented way, governing global risks is humanity's great challenge.