Rich Lowry of National Review Online isn’t buying the argument that America is following Rome’s historical example.

It is true that Rome’s fall — a long, messy process — didn’t unfold with the pleasing cinematic simplicity that the popular imagination might believe; the extent of the barbarian population transfers has been exaggerated, and the eastern half of the empire lived on for another 1,000 years.

Still, the Western Roman Empire unquestionably fell, with disastrous consequences for a long time. It’s just that dragging us into it is wildly off base.

Rome tore itself apart with constant assassinations, usurpations, and civil wars. It weakened itself economically and militarily, while confronting challenges from armed bands on its borders that it became incapable of handling as it steadily lost its territory and sources of financial support to barbarian groups.

At the same time, it had to grapple with the Persian Empire to the east.

Is this happening to the United States? Well, an armed contingent of Quebecers isn’t (like the Visigoths) wandering throughout the United States, fighting periodic battles with the U.S. military and seeking subsidies from the U.S. Senate before besieging — and eventually sacking — Washington, D.C.

Migrants to the United States don’t settle en masse in national groupings led by military leaders seeking power and preferment. They disperse throughout the country and take illegal jobs as busboys and the like.

U.S. presidents have to worry about declining poll numbers, a recalcitrant congressional opposition, and reelection campaigns.

They don’t, like Roman emperors, need to think all the time about potential assassinations and armed usurpers. They don’t need to worry that if they assign a general to take over, say, CENTCOM, he will use the position to muster the troops and resources to challenge for power himself. They don’t need to consider the positioning of military forces with an eye to checking internal enemies.