With government shutdown now the longest in American history, we have passed a quantifiable moment by which Donald Trump’s presidency has brought America a new degree of governmental dysfunction. Our government exists to solve our largest and most complex problems, which have mounted exponentially over the decades since the last lengthy shutdown, in 1995-96.  By shutting down the government over a fake solution based on an obvious lie, Trump epitomizes the contradictory nature of his presidency: He says he wants to make America great again, but everything he does makes America worse.

His persistence on a wall stems partly from the fiction that the wall will at least solve our immigration crisis, thus helping our own struggling people.  He cites it as a “medieval” solution that works.

Medieval history shows the opposite.

The most famous wall on Earth is the Great Wall of China, built and rebuilt many times over three millennia to keep out Mongolian raiders.  The Great Wall reached its peak during the glorious Ming Dynasty (1368-1644), which has been called “one of the greatest eras of orderly government and social stability in human history.”

Yet what became of the Ming?  As we discuss on a recent episode of the Democrises podcast, the Great Wall could not protect the Ming from its internal failings.  It ultimately succumbed to the factors that mathematical historian Peter Turchin says usually bring down great civilizations: overpopulation, elite incompetence, and collapsing state finances.

According to historian John Keay, the Chinese population grew from about 90 million in 1368 to 275 million by 1600, well over the population of 40 million to 100 million population it had maintained for the previous two millennia.

The elites especially overpopulated, with many members of the Ming lineage producing up to 50 children each.  According to Keay, “By the seventeenth century, the number of imperial dependents ran to tens of thousands,” their state stipends eclipsing the military budget as the empire’s top expense.

They tried to pay for this by heavily taxing the peasants, who soon ran out of money.  After a few generations of untenable feudalism, Ming cohesion melted away, and the society crumbled from within.  Manchu invaders easily overcame the Great Wall, conquered China and established the Qing Dynasty (1644-1912), ruling over China as foreigners.

The Qing would follow the boom-and-bust trajectory of the Ming.  The Qing Dynasty first extended China’s borders to its all-time zenith, produced intellectual achievements like an 800,000-page encyclopedia, and initially presided over internal peace.  Its emperor proclaimed it was “the hub and center about which all quarters of the globe revolve.”

Then it again began rotting internally, and rulers tried to seal its borders.  In 1793 A.D., a delegation from Great Britain arrived requesting freer trade.

The Qing emperor, drunk with arrogance about Chinese exceptionalism, and fearful of what engagement with the world might do to Chinese culture, dismissed Britain as a “barbarian” nation from “a remote and inaccessible region, far across the spaces of the ocean,” and that only “by perpetual submission to our Throne, you may secure peace and prosperity for your country.”

A half-century later, that same remote island humiliated China in the First Opium War.  Britain destroyed the Chinese Navy, occupied Shanghai, and forced China to accept legal opium and cede Hong Kong, along with countless other degradations.  The ensuing “Century of Humiliation” brought China many tragedies, including the 1850-1864 Taiping rebellion with 18 million deaths and the 1937 Rape of Nanking.  It culminated with China’s disastrous Great Leap Forward in 1962, when famine made it the 10th poorest country on Earth.

Indeed, walls are useless under two conditions: when a society rots internally, and when it faces a wave of determined and desperate people.  Trump’s America faces both.

I am a physician, just having returned from the Congo, where I was helping to fight Ebola.  Despite its 90 percent mortality rate, Ebola’s threat pales in comparison to the more mundane challenges of poverty and overpopulation.  The population of Congo has increased from 13 million people to 80 million in only 60 years.  The Congolese live in crushing poverty, with hunger and instability stemming from their corrupt governance, anarchic violence and minimal infrastructure.

Such misery abroad has consequences for the West.  Economic migrants today stream from south to north in both hemispheres, existentially stressing our societal cohesion.  They also flee violence, especially in Latin America.  Of the top 50 most violent cities on Earth outside combat zones, 41 are in Latin America.

Walls won’t help solve this immigration crisis because—as in China—America’s greatest threats are internal, epitomized by our selfish, dishonest, and debtor president.  That may be why he focuses on fake solutions, but we cannot let him distract us.  Our opioid and suicide epidemic signal the depth of despair among America’s former middle class. Financial Times columnist Ed Luce has noted that the hollowing out of the middle of our politics reflects the hollowing out of the American middle class.  We have run up a $21 trillion debt to compensate for the many Americans suffering today, as globalization and automation keep constant pressure on their jobs, but that cannot continue forever.”

Instead of walls, America must marshal our economic potential to help struggling people at home and abroad.  Past successes in this arena like the Marshall Plan and the New Deal required America’s government operating at its best.

By instead shutting the government over his wall, Trump fulfills the immortal warning of British historian Arnold Toynbee, concluding his opus on the rise and fall of 26 civilizations: “Civilizations die by suicide, not by murder.”