When castigating the New York Times’ “1619 Project” for practicing “historical revisionism,” Katherine Kersten contends that “America is not exceptional because it once allowed slavery but because its founders launched us on a great and unprecedented experiment in democratic self-governance” (“1619 revisited, revisited,” Dec. 8).

The historians (scholars like me) who contribute to this Project, Kersten charges, are inventing “distortions, half-truths and outright falsehoods.” Our supposed aim is to advance our leftist “political agenda” that promotes white guilt, black victimhood and narrow-minded political correctness.

The 1619 Project has serious flaws that historians are currently examining. But what, specifically, is this supposed “outright falsehood”? According to Kersten, we are purposely suppressing the fact (one that every historian actually acknowledges freely) that since time immemorial, people the world over have enslaved one another. Moreover (again as we all know), we are still at it.

All this proves to Kersten’s satisfaction that 240 years of brutal enslavement that saw 4 million African-­Americans in shackles on the eve of the Civil War was, historically speaking, normal business. After all, everywhere and at all times, everyone who could enslave did enslave. Her advice echoes White House Chief of Staff Mick Mulvaney’s on another matter: “Get over it!”

But if you refuse and instead insist that Kersten deal directly with American slavery, she cravenly shifts to a shopworn right-wing gambit we recognize as a “whattabout.” (What about Ukraine’s secret server? The Deep State? Hilary’s Clinton’s e-mails?) What, she asks, about ancient enslavers such as the Greeks, Romans, Asians, Aztecs and Incas? What about slavery in colonial Brazil, Haiti, the British Caribbean sugar islands and Cuba? What about slavery today in Pakistan, India and China? If practically everyone was or is implicated in slaveholding, she insists, what’s the big deal? Don’t fall for historians’ “outright falsehood” that the taint of human bondage has given us exceptional history. Lots of people have always done it and still do.

But it remains undeniable that slavery has given the United States a history that is not only one of a kind but profoundly disturbing. Consider:

Every government in the Western Hemisphere except revolutionary Haiti’s and ours voted slavery out of existence without firing a shot. For us, the cost was 750,000 dead Americans, a mind-numbing number that still exceeds the total casualties we’ve absorbed in all other wars combined.

No other government in the Western Hemisphere but ours gave slavery a new lease on life when given an opportunity to abolish it wholesale. We alone wove slavery’s protection throughout our new Constitution. Among our first 12 presidents, only two, both named Adams, never owned slaves. Throughout the Western Hemisphere, only our President Thomas Jefferson had the exceptional nerve to claim “all men” as “equal” but refused to recognize the children of his enslaved mistress.

Only in the United States did slavery constitute a national economy’s second-largest capital asset, exceeded only by holdings in real estate. (The 1850 inflation-adjusted price of a prime, male, Mississippi field hand topped out at over $30,000.) But there’s more:

Our Founding Fathers, no one else’s, made the calculated decision to legalize slavery and slave trading in their nation’s seat of government. Only in Washington, D.C., did tourists gaze upon the enormous “slave mart” across the street from the House of Representatives and on enslaved laborers constructing the Capitol dome. Only the United States countenanced an enormous internal slave trade. Ours wrenched close to 1 million enslaved people from their loved ones and marched them in chains from Virginia and Maryland to sell at enormous profits in the lower South. And there’s still more:

After emancipation, no country except ours systematically stripped the formerly enslaved and their descendants of their rights and terrorized them constantly for nearly a century.

None but ours makes dead slaveholders into eternal heroes by building elaborate statues in their honor.

Kersten recommends that we discount our nation’s slavery-haunted past and get over it. The more intelligent and ethical choice by far is to study our nation’s unique chronicle of injustice and reflect on what it suggests about how to push back against our own rising tide of white supremacy.

James Brewer Stewart, the James Wallace Professor of History Emeritus at Macalester College, is the founder of Historians Against Slavery (http://historiansagainstslavery.org) and the author/ editor of 12 scholarly books addressing the history of American slavery and its abolition.