A boat carrying migrants stranded in the Strait of Gibraltar in September. (Credit: Marcos Moreno/Agence France-Presse -- Getty Images)

If we fail to learn from the past, we do so at our own peril. That was one of the messages from the Chinese artist-activist Ai Weiwei to a gathering of world leaders, academics and activists at the Athens Democracy Forum here last week.

“There’s a potential to totally forget the past, and not to remember those lessons we have learned,” said Mr. Ai, who spoke in support of migrants around the globe. “We have a potential to be very mean, to be hateful, not only to close in but really damage others, and to use some excuse and reason to separate humanity. I think that is part of human nature.”

Mr. Ai, whose recent artwork has been inspired by the plight of refugees, said that all countries needed to unite and assert “global leadership” on the issue of migration, because it was “not going to stop” and might worsen because of environmental disasters, famine and population growth. Yet a strikingly different response to global migration came from others at the forum, which was convened by The New York Times in cooperation with the city of Athens and the United Nations and is in its sixth year.

“What’s corrupting politics in Europe today is the influx of migrants,” said Kishore Mahbubani, former ambassador to the United Nations from Singapore, “and that clearly is shifting the debate in Sweden, Germany and everywhere to the far right.” Mr. Mahbubani, a professor at the National University of Singapore, then suggested that Europe should consider a “strategic pause” on immigration.

“That way the populations can breathe a sigh of relief,” he added, speaking at the panel, “The Allure of the Illiberal.” “Then the political debate will shift to the middle, where you want it to be.” Otherwise, “you’re going to end up with illiberal regimes because of liberal principles.”

Immigration was a prominent part of the overall theme of the forum: that liberal democracy is facing perils on multiple fronts and must be defended to prevent the rise of more dictatorships.

“Arch,” by Ai Weiwei, installed at Washington Square Park in New York. The artist-activist created a series of public artworks on immigration, titled “Good Fences Make Good Neighbors,” in 2017. 
(Credit: Vincent Tullo/The New York Times)

Participants at the conference — government officials, lawmakers, academics, business leaders and activists — warned that core components of democracy were being challenged in the United States and Western Europe, but also in Eastern Europe, Turkey, Venezuela, Sweden and India. The rule of law is being eroded, the press is being discredited, if not silenced, and social media is being used to spread illiberal ideas and sway elections.

“The threat we face is very, very real,” said Yascha Mounk, a lecturer on government at Harvard and the author of “The People vs. Democracy.” “If you care about liberal democracy, if you care about those values, those are now imperiled in a very serious way.”

Mr. Mounk said that people were “falling out of love with democracy at alarming rates.”

For instance, he noted, less than a third of millennials in the United States considered it essential to live in a democracy. And across Europe, the average vote share of populist parties had more than doubled, to 20 percent from 8 percent, since the late 1990s.

He attributed the surge in populism to economic stagnation; a shift from monocultural societies to multicultural ones following mass migration; and the rise of technology, which allowed “fake news to spread, fabrications to be accepted as gospel and hate to have a real voice in our system,” Mr. Mounk said.

Under the circumstances, he warned, political systems that were “not sufficiently democratic” could easily morph into dictatorships.

Hungary was held up as an example of the populist peril by several panelists, including Mr. Mounk. There, Prime Minister Viktor Orban has applauded “illiberal democracies” in places such as Turkey, China and Russia, and undermined the rule of law. His example is being followed by Poland.

Karolina Wigura of the Polish think tank Kultura Liberalna placed blame for recent developments on a state of amnesia.

While previous generations in Europe had a fear of World War II, she said, “with time, this fear of the past evaporated, and there was a certain shift from the fear of the past to the fear of the future” — concerns about migrants, one’s economic well-being and job prospects.

“And the fear of the future is the passion that is best embraced by the populists.”

Another issue at the forum was the role of social media in amplifying illiberal ideas and affecting election outcomes.

Facebook (a conference sponsor) was criticized for being too slow to react to the discovery that thousands of ads had been bought by Russians to mislead American voters in the 2016 presidential election and that the data analytics firm Cambridge Analytica had used personal information from up to 87 million Facebook users to compose targeted political ads in the United States.

Damian Collins,  a member of the British Parliament who is chairman of its Digital, Culture, Media and Sport Committee,  said Facebook was taking actions only after these episodes had been uncovered.

“We’ve got these disclosures because the company has been forced into doing it,” he said. “There should be more transparency about the internal investigation Facebook is running. “It’s not good enough for us to get things piecemeal, when Facebook feels like telling us.”

Richard Allan, Facebook’s director of policy in Europe and a member of the British House of Lords, replied: “We’ve admitted that we’ve made mistakes. We weren’t particularly focused on various vectors of attack, and so trust has been damaged.”

Mr. Allan acknowledged that there was “a need for us to be accountable externally.”

At the same time, he said, Facebook’s efforts had to be verified. “I do think that people want some formal regulatory body to be testing that proposition and either saying, ‘Yes, you’re right, Facebook, you’ve done a good job,’ or ‘No, actually, it’s all smoke and mirrors.’”

Mr. Allan said that in the first quarter of the year, Facebook had stopped 583 million fake accounts from going live, in a “robot war” led against computers that randomly generate names and try to register as many as 1,000 Facebook addresses per hour.

Facebook was also hiring 10,000 more ad reviewers, engineers, security experts and others working on improving user safety.

Ultimately, the populist tide has to be combated by individual citizens, said Mr. Mounk, the Harvard lecturer. He recalled the recommendation of Amos Oz, the Israeli author, that if you witnessed a calamity or a fire, you could always bring a bucket or glass or teaspoon of water to help put it out.

Mr. Mounk suggested that conference attendants do exactly that. “There are a lot of us in the room. We all take a bottle of water and take it to the fire together,” he said. “The future of our political system is in our hands, and I think it’s our duty as citizens to fight for it.”

Farah Nayeri writes on culture for The New York Times. Based in London, she was previously the arts correspondent of Bloomberg.