We Americans tend to have an overly inflated sense of our place in this world. If there is an enemy, we must defeat it. If a global challenge looms, we must lead the way forward. When somebody reaches for a weapon, we must strike before they can use it (against us, naturally). And should we fail to do so, we would be to blame for whatever tragedy might result.
That's not to say that our sense of global responsibility doesn't have deep and logical roots. Armed with the world's largest gun after World War II, we set about creating an international liberal trade order that we believed would transform global affairs. And we have succeeded beyond our wildest dreams -- ending great-power war, integrating vast chunks of the planet into a globalized market economy, enabling the simultaneous rise of numerous great powers (and their populations), and fueling the emergence of a worldwide middle class. Each of these historical "firsts" remains a game-changer, and collectively they have yielded the unprecedented global peace and prosperity we enjoy today -- no matter what mass-media fear-mongers feed us.
With these successes, of course, have come enormous strains. Rising resource requirements will demand efficiencies of an entirely new order. Environmental pressures will compel us to move ever-more-rapidly down the carbon chain. Globalization's social reformatting process will draw us into fixing all manner of fake and failing states (primarily to secure the liberation of women suddenly freed from tradition's grasp). The list of problems to be solved goes on and on -- and yet, this is humankind's best set of problems yet! Because within them lie the seeds of future successes -- but only if we maximize our definitions of "us" and narrow our definitions of "them."