It has seemed to me for some time that rather than the old adage "All Empires fall", it would be far more apt to say "All Empires think they are falling."

Take for instance Rome; Even before the Republic fell, there are writers like Sallust who hammered on about moral decline and how the old days were better and, when the Republic and later the Empire fell, people nodded sagely and said "Ah yes, our morality has slipped. Such is the way of Empire." Let's face it, nostalgia for an earlier, simpler time is a pretty strong motivator for a great many people and this is just an extension of that. In reality, their morality was not slipping and any person who held that opinion today would be roundly ridiculed. But reality matters little to people who are observing the past looking for evidence of why their perceived present is so poor.

Those Americans who claim that America is 'falling' are just saying what seems obvious to them with their nostalgia-tinted glasses. They are just saying it differently (though people do still hammer on and on about moral decline). In this case they are just putting it within the modern discourse that makes sense to them - they are seeking out statistics and figures that seem to confirm their view, nodding sagely and saying "Ah yes, our economy has slipped. Such is the way of Empire." The statistics don't back them up, but that matters little because it isn't the statistics that are confirming their worldview - it is their view of a past where America was on top of the world.