Contrary to an optimistic vision of a world "flattened" by the virtues of globalization, the sustainability and positive outcomes of economic and political homogenization are far from guaranteed. For better and for worse, globalization has become the most powerful force shaping the world's geopolitical landscape, whether it has meant integration or fragmentation, peace or war. The future partly depends on how new economic giants such as China, India, and others make use of their power. It also depends on how well Western democracies can preserve their tenuous hold on leadership, cohesion, and...