A scene from the riot on Capitol Hill, Jan. 6.

Photo: Douglas Christian/Zuma Press

On Wednesday afternoon I checked in with a Latin American friend to get his thoughts about the chaos on Capitol Hill. “It looks like home,” he quipped.

It was not a unique reflection. By evening a popular observation making the rounds was that the invasion of Congress was the stuff of banana republics. The bedlam also evoked memories of what happened in many U.S. cities over the summer when the Black Lives Matter marches turned violent.

There was a big difference between Wednesday and the American summer of terror. During the latter it was merely a presidential candidate (
Joe Biden

) who refused to condemn the BLM violence—until he realized it was hurting his polls numbers. Last week it was a sitting U.S. president who stirred up the passions of his followers and continued to justify their anger even after it was clear they were breaking the law, endangering lives, damaging property, and attempting to disrupt an independent branch of government. President Trump may have set a new modern-day low.

Yet the main worry is that political violence in the U.S. on both the left and the right seems to be on the rise. It won’t recede as long as mob action is tolerated as a way to do politics.

A first step in reversing the trend is admitting that the slash-and-burn tactics of both sides are similar. Both justify violence under the banner of “participatory democracy.” Storming the Capitol or burning down a
is the people speaking.

Participatory democracy as defined by extreme groups has been put into action in the U.S. before. The leftist upheaval in the streets of Seattle against the World Trade Organization ministerial conference in 1999 is one memorable example. It is no coincidence that elements of Mr. Trump’s base oppose free trade and globalization.

Traditional American democracy is “deliberative democracy,” a process by which elected representatives use reason and debate to shape public policies. Participatory democracy tells the aggrieved: Never mind the legislature. Go to the streets to get what you want.

A 2013 paper by Italian philosopher

Antonio Floridia
traces the origins of participatory democracy to the 1960s in the U.S., “inspired by the great youth movements of that decade.” Mr. Floridia cites the American political scientist

Jane Mansbridge,
who writes that the term “came into widespread use” after Students for a Democratic Society “gave it a central place in its founding Port Huron Statement.” Ms. Manbridge adds: “What the term meant then was unclear, and it became less clear afterward, as it was applied to virtually every form of organization that brought more people into the decision-making process. In the actual organizations of the New Left, however, the term came to be associated quite quickly with the combination of equality, consensus and face-to-face assembly.”

In practice this approach seems to give way to a mob rule in which passionate believers, though unelected, gain power by organizing. When the other side discovers similar ways to check them, the participants, believing themselves democratic, employ physical intimidation.

In a 2009 essay titled “Farewell to the ‘End of History’: Organization and Vision in Anti-Corporate Movements,” the leftist Canadian author

Naomi Klein
explained why, in 2001, the antiglobalization World Social Forum chose Porto Alegre, Brazil, for its first annual confab: The Workers’ Party (PT) was in power in both the city and in the state of Rio Grande do Sul and it had “become known world-wide for its innovations in participatory democracy.”

That “innovation” was a clever way to circumvent election results. The PT sought to control the city’s budget but repeatedly failed to win control of the city council at the ballot box. So the party organized political operatives (unions, garbage-collection companies, etc.), labeled them grass-roots groups and used them to apply pressure to the council. This undemocratic end-run became known as “participatory budgeting.”

The strategy was considered a great success—until other parties began to organize their own political operatives. Meanwhile, the PT exported the idea to other parts of Brazil and beyond. Latin America, where

Fidel Castro
attempted to replicate the Soviets’ Third International with the annual Foro do São Paulo, was fertile ground.

The breakdown of democratic institutions in the region coincides with the use of the term “participatory democracy” as a way of suffocating pluralism and tolerance. Wherever mere political activism by organized pressure groups is not enough (because two can play that game), soviets claiming grass-roots legitimacy take matters into their own hands. Bolivia, where mobs blocked highways to paralyze the country and bring

Evo Morales
to power, and Venezuela, where “colectivos” were unleashed to enforce chavismo, are the most extreme cases, but there are many others.

The U.S. is supposed to be different. But it won’t be if the reprehensible use of mob violence is legitimized as participatory democracy.

Write to O’Grady@wsj.com.

Potomac Watch: A politician has to work hard to destroy a legacy and a future in a single day. President Donald J. Trump managed it. Image: John Minchillo/Associated Press

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