Is American decline a myth?

Yes, according to Robert Kagan, whose eloquent and clearly influential essay on the subject has become required reading for anyone interested in American exceptionalism and decline — including, it seems, President Obama, who was influenced by the article, "discussing it at length" in an off-the-record meeting on the afternoon of his State of the Union address. Money quote:

If the United States is not suffering decline in these basic measures of power, isn’t it true that its influence has diminished, that it is having a harder time getting its way in the world? The almost universal assumption is that the United States has indeed lost influence. Whatever the explanation may be—American decline, the “rise of the rest,” the apparent failure of the American capitalist model, the dysfunctional nature of American politics, the increasing complexity of the international system—it is broadly accepted that the United States can no longer shape the world to suit its interests and ideals as it once did. Every day seems to bring more proof, as things happen in the world that seem both contrary to American interests and beyond American control.

And of course it is true that the United States is not able to get what it wants much of the time. But then it never could. Much of today’s impressions about declining American influence are based on a nostalgic fallacy: that there was once a time when the United States could shape the whole world to suit its desires, and could get other nations to do what it wanted them to do, and, as the political scientist Stephen M. Walt put it, “manage the politics, economics and security arrangements for nearly the entire globe.”

Money quote II: "Foreign policy is like hitting a baseball: if you fail 70 percent of the time, you go to the Hall of Fame." The whole piece is worth reading.