America is experiencing a diversity and inclusion conundrum—which, in historical terms, has not necessarily been a good thing. Communities are tearing themselves apart over the statues of long-dead Confederate generals. Controversy rages over which slogan—“Black Lives Matter” or “All Lives Matter”—is truly racist. Antifa street thugs clash with white supremacists in a major American city. Americans argue over whether the USC equine mascot “Traveler” is racist, given the resemblance of the horse’s name to Robert E. Lee’s mount “Traveller.” Amid all this turmoil, we forget that diversity was always considered a liability in the history of nations—not an asset.

Ancient Greece’s numerous enemies eventually overran the 1,500 city-states because the Greeks were never able to sublimate their parochial, tribal, and ethnic differences to unify under a common Hellenism. The Balkans were always a lethal powder keg due to the region’s vastly different religions and ethnicities where East and West traditionally collided—from Roman and Byzantine times through the Ottoman imperial period to the bloody twentieth century. Such diversity often caused destructive conflicts of ethnic and religious hatred. Europe for centuries did not celebrate the religiously diverse mosaic of Catholic, Orthodox, and Protestant Christians, but instead tore itself apart in a half-millennium of killing and warring that continued into the late twentieth century in places like Northern Ireland.

In multiracial, multiethnic, and multi-religious societies—such as contemporary India or the Middle East—violence is the rule in the absence of unity. Even the common banner of a brutal communism could not force all the diverse religions and races of the Soviet Union to get along. Japan, meanwhile, does not admit many immigrants, while Germany has welcomed over a million, mostly young Muslim men from the war-torn Middle East. The result is that Japan is in many ways more stable than Germany, which is reeling over terrorist violence and the need for assimilation and integration of diverse newcomers with little desire to become fully German.

History offers only a few success stories when it comes to diversity. Rome, for one, managed to weld together millions of quite different Mediterranean, European, and African tribes and peoples through the shared ideas of Roman citizenship (civis Romanus sum) and equality under the law. That reality endured for some 500 years. The original Founders of the Roman Republic were a few hundred thousand Latin-speaking Italians; but the inheritors of their vision of Roman Republican law and constitutionalism were a diverse group of millions of people all over the Mediterranean.

History’s other positive example is the United States, which has proven one of the only truly diverse societies in history to remain fairly stable and unified—at least so far. Although the Founders are now caricatured as oppressive European white men, they were not tribal brutes. The natural evolution of their unique belief that all men are created equal is today’s diverse society, where different people have managed, until recently, to live together in relatively harmony and equality under the law.

Unlike present-day Mexico, China, or Japan, America never developed a fixed idea, either culturally or formally in its written constitution, that race or religion de facto defined citizenship. Instead, an imperfect America was always being reinvented in dogged pursuit of the Founders’ promise of equality and the toleration of difference.

Despite a Civil War that took over 600,000 lives, years of oppression and segregation, dozens of major riots, and thousands of court cases and legislative fights, our American exceptionalism held that America alone could pull off the bizarre idea that diverse peoples could eventually live together as a single people in brotherhood. But the American experiment is not static, nor is it settled. The nation’s racial, ethnic, and religious diversity is by nature volatile, and prone to exploitation by demagogues and opportunists.

A diverse America requires constant reminders of e pluribus unum and the need for assimilation and integration. The idea of Americanism is an undeniably brutal bargain in which we all give up primary allegiance to our tribes in order to become fellow Americans redefined by shared ideas rather than mere appearance.

Unfortunately, there are increasing signs that our political, religious, ethnic, and racial diversity is overwhelming our shared but fragile notion of national unity. Growing geographical separation into blue coastal liberal states and red interior conservative counterparts is starting to mimic the North-South regional divide of the Civil War, a split in national geography that is fueling political differences. Not surprising, there is talk of a Calexit, or a Confederate-like secession of California from the United States—and during the Obama administration, there was news of a secessionist movement in Texas.

There is currently little real free speech on American campuses. A new kind of racial segregation is occurring in college “theme” and “affinity” houses. Recent street violence in places like Charlottesville between extremists of the left and right resembled the brawling between totalitarian Stalinists and racist brown shirts of 1930s Germany. The successful melting pot is caricatured; the unproven salad bowl is canonized.

Almost everything in America today is politicized and thus polarized, from the fundamental to the trivial: sports events, music, art, Hollywood movies, mute statues, cable television, university curriculums, Silicon Valley corporations, and now even the names of horses. Fewer people are unified. The schools and the media do not remind Americans that their country can be quite good without having to be perfect—and is far better than the contemporary alternatives elsewhere. At the same time, these institutions have convinced Americans that the evils of human kind—racism, sexism, homophobia, slavery, serfdom, and class oppression—are the unique sins of democratic America. Few today appreciate that only in America has there been a culture of self-critique, introspection, and dissent—and thus remedies for the nation’s shortcomings, a self-correcting culture not known elsewhere.

The fashion today is to identify yourself by your ethnicity, race, or sexual preference—as something that transcends both being American and a unique individual. In contrast, there are vanishing incentives for people to simply call themselves Americans, allowing the content of their character to trump the color of their skin. In this regard, we can welcome the recent change in name of the preeminent Latino lobbying group from the racialist National Council of La Raza to Unidos US. (Raza is a Franco-era chauvinistic buzzword meaning “The Race.”)

If America is to survive this fourth century of its existence, it will soon have to recalibrate from “celebrating diversity” to “celebrating unity.” The bleak alternative is history’s long list of genocides, tribal feuding, ethnic warring, religious conflicts, and pogroms. In sum, the United States will at some point have to subordinate the fad of multiculturalism to the ideal of multiracialism: many different-looking Americans who are nonetheless one in their shared customs, citizenship, and culture, while holding diverse political and cultural views not predicated on identity politics.

“Difference” is a plus when it is a matter of enjoying diverse foods, music, fashion, art, and literature that enhance a central, shared, and unchanging set of values based on the Declaration of Independence, the Constitution, and the Bill of Rights.

We all enjoy Mexican or Chinese food, but not Mexican or Chinese ideas of democracy and human rights. We all are enriched by Caribbean music but not by Caribbean notions of law and justice. We all value political and ideological diversity—but only when they rely on collective tribal allegiances. And we are impressed by Middle Eastern hospitality and family solidarity, but not Middle Eastern treatment of women, minorities, gays, and diverse religions. What makes millions of immigrants strive to reach and stay in America at all costs is not our racial make-up or our many languages but the racially-blind promise of freedom, liberty, the rule of law, prosperity, and security which are the dividends of Americans abiding by the precepts of the U.S. Constitution.

If America’s set of values becomes a pick-and-choose potpourri, there is no unity. And then America will certainly become yet another one of history’s casualties of diversity.