Historian Niall Ferguson made some extended remarks recently arguing that the American empire may be closer to the edge than many suppose.
He starts out observing that while the fateful decline of American supremacy is now widely accepted, it is still generally expected that this will be a protracted process. After all empires don't fall in a day. Rome took centuries to crumble did it not? Wrong. Ferguson cites examples such as the fall of ancien regime France, the Soviet Union, and the British empire in the postwar period, to show that the collapse of empires often arrive suddenly, take people unawares, and have profound and enduring consequences.
Another strand to the argument is that empires are best understood well ordered complex systems. Such systems by their nature give an appearance of permanence and durability that belie their vulnerability to fatal shocks. A forest for example appears very stable as it has its own complex systems for maintenance and repair that sustain equilibrium for very long periods of time. And that is true, until a forest fire arrives one day and fatally undermines that equilibrium.
If empires are complex systems that are susceptible to sudden collapse then what is a common trigger? Again citing historical examples Ferguson argues that fiscal crises are the most common harbinger of serious trouble for sprawling empires. Just such a crisis is what the United States now faces.
See the full speech here (the introduction is boring, Niall Ferguson starts speaking about nine and a half minutes in):
