If the American experiment dies, the cause will be terminal bothsidesism.

This is not to deny that our politics is ideologically bipolar. There is a party of the left that advocates ambitious government and progressive social values. There is a party of the right that defends limited government and conservative social virtues. The differences between the sides concern the largest matters of penury or prosperity, sickness or health, death or life.

But the genius of American government has been to contain fundamental policy disagreements within a legal structure where political victory is never total and political loss is never final. And Americans have generally viewed this liberal democratic framework not only as an efficient form of self-government but as a noble one.

People may be rivals in a balance of power, but they are also partners in a great enterprise. America coheres due to shared pride in a brilliant set of democratic procedures crafted in the 18th century. And the successful operation of that system presupposes citizens with certain democratic ideals: a respect for truth, the rejection of politically motivated violence, a commitment to social and political equality, and reverence for the rule of law.

Is it possible to locate ideological hotheads on both left and right who care nothing for democratic procedures and values? Of course. In a country of 330 million people, one can find plenty of anarchist rioters, Marxist college professors and administrators who use tolerance as a club to beat those they deem intolerant. But judging their threat as equivalent to that of the populist right is itself a threat to the country. At some point, a lack of moral proportion becomes a type of moral failure.

My main concern here is with previously rational and respectable conservatives who are providing ideological cover for the triumph of Trumpism on the right. Often some scruple prevents them from joining fully in former president Donald Trump’s gleeful assault on democratic legitimacy. So their main strategy is to assert that leftist depredations against democracy are equivalent. If both sides have their rioters and petty autocrats, why not favor the rioters and petty autocrats whose success will result in better judges?

But here’s the rub: By any rational standard, both sides are not equivalent in their public effect.

Only one party has based the main part of its appeal on a transparent lie. To be a loyal Republican in 2021 is to believe that a national conspiracy of big-city mayors, Republican state officials, companies that produce voting machines and perhaps China, or maybe Venezuela, stole the 2020 presidential election. The total absence of evidence indicates to conspiracy theorists (as usual) that the plot was particularly fiendish. Previous iterations of the GOP tried to unite on the basis of ideology and public purpose. The current GOP is united by a common willingness to believe whatever antidemocratic rot comes from the mouth of an ambitious, reckless liar.

Only one side of our divide employs violent intimidation as a political tool. Since leaving the presidency, Trump has endorsed the view that the events of Jan. 6 were an expression of rowdy patriotism and embraced the cruel slander that the Capitol Police were engaged in oppression. Turn to Fox News and hear hosts and guests referring to a coming “purge” of patriots, alleging that the left is “hunting” the right with the goal of putting conservatives in Guantánamo Bay, and speaking of “insurgency” as a justified response.

Only one political movement has made a point of denying the existence and legacy of racism, assuring White people that they are equally subject to prejudice, and defending the Confederacy and its monuments as “our heritage.” This is perhaps the ultimate in absurd bothsidesism. My side suffers from economic stagnation and the unfair application of affirmative action. Your side was shipped like coal and sold like cattle; suffered centuries of brutality, rape, family separation and stolen wages; and was then subjected to humiliating segregation and the systematic denial of lending, housing and justice. Who can say which is worse?

Only one president — as released documents show — attempted to overturn the results of a fair election, tried to block the certification of his successor and discussed in the Oval Office the possibility of imposing martial law. Only one president had minions prepare the step-by-step instructions for a constitutional coup.

I could go on. Yet it gives me no pleasure. I would prefer to witness the return of a principled party of the right because I hold many conservative views on policies that I’d like to see enacted. But when fellow conservatives claim that the GOP remains the best of bad options, they become contributors to the ruin of our democracy. Only one party in the United States is committed to liberal democracy. And in the absence of that commitment, influence is merely the will to power.