Most Americans believe that the United States is in decline. To support that belief, eyes inevitably turn to the example of Ancient Rome for parallels between their fall and our supposed decline.

There are many theories behind the cause of Rome’s fall. However, I frequently come across one theory more than any others. Simply put, it’s that Rome fell because it became too big for its own good.

The most famous exponent of this theory is Edward Gibbon, who in his Decline and Fall of the Roman Empire (1781) wrote:

“But the decline of Rome was the natural and inevitable effect of immoderate greatness. Prosperity ripened the principle of decay; the causes of destruction multiplied with the extent of conquest; and, as soon as time or accident had removed the artificial supports, the stupendous fabric yielded to the pressure of its own weight. The story of its ruin is simple and obvious; and, instead of inquiring why the Roman empire was destroyed, we should rather be surprised that it had subsisted so long.”

Almost fifty years before Gibbon, the French political philosopher Montesquieu concluded essentially the same thing in The Greatness of the Romans and Their Decline (1734). When Rome began to expand, and granted citizenship to peoples of various traditions, it lost its unity:

“After this, Rome was no longer a city whose people had but a single spirit, a single love of liberty, a single hatred of tyranny… The distracted city no longer formed a complete whole. And since citizens were such only by a kind of fiction, since they no longer had the same magistrates, the same walls, the same gods, the same temples, and the same graves, they no longer saw Rome with the same eyes, no longer had the same love of country, and Roman sentiments were no more.”

According to Gibbon and Montesquieu, Ancient Rome began to decline when it lost its identity both through expansion and increased heterogeneity. By growing too large and diverse, the ideological unity that initially held the republic together was eroded and replaced with a superficial unity.  

Has the same thing happened to America?