During a historic speech delivered in his adopted hometown of Chicago on Tuesday night, President Barack Obama reflected on his eight-year tenure in the Oval Office, during which he pushed progressive policies through an obstructionist Republican Congress, and offered hope for the days and years ahead. Obama, the first president to embrace the rise of social media, and whose two decisive victories were undergirded by a reliance on micro-data, also offered a warning about filter bubbles and the dangers of fragmentation, in real life and on social media, alike:

”For too many of us, it’s become safer to retreat into our own bubbles, whether in our neighborhoods or college campuses or places of worship or our social media feeds, surrounded by people who look like us and share the same political outlook and never challenge our assumptions. The rise of naked partisanship, increasing economic and regional stratification, the splintering of our media into a channel for every taste—all this makes this great sorting seem natural, even inevitable. And increasingly, we become so secure in our bubbles that we accept only information, whether true or not, that fits our opinions, instead of basing our opinions on the evidence that’s out there.”

When Obama ran for president in 2008, he saw a nation fractured by a war in Iraq and the pre-natal pangs of what is now fully recognized as a crisis of widespread inequality. He ran his campaign on an amorphous but powerful platform of hope, promising to fight partisanship and find consensus and common ground. But since then, those trends have only become exacerbated. In 2008, Twitter and Facebook existed, but they weren’t dominant forces with hundreds of millions and billions of users, respectively. Nobody was getting their daily news from their Facebook news feed.

Today, 62 percent of U.S. adults say they get their news from social media, often relying on news stories shared within their own self-selected digital bubbles. Facebook, which has finally accepted some culpability for its role in disseminating unchecked misinformation, is still experiencing growing pains as it evolves, whether willingly or not, from a social network into a media company. But the problem runs deeper. Studies in recent years suggest media fragmentation has increased partisanship—that is, paradoxically, the vast array of news outlets at our disposal today have given way to more explicitly ideological ones and have helped contribute to an increase in partisanship and polarized political opinion. (This is true not only for news media, but, with the rise of streaming services, it applies to entertainment, too.)

John Duca and Jason Saving, both economists at the Federal Reserve Bank of Dallas, concluded in an August 2016 study that a plurality of news sources actually decreases exposure to alternate viewpoints, which ultimately leads to an echo-chamber effect and prevents people from having empathy to understand rival perspectives. “This may be reinforced by a tendency for political differences to be decreasingly addressed through genuine debate and increasingly replaced with media coverage of political vilification or grandstanding,” the men wrote.

Now, Obama warned, the fragmentation occurring on social media is threatening the foundations of our democracy. In a brave new world where there’s no precedent for the echo-chamber effect, there are few answers. Obama offered a distinctively retro one on Tuesday night. “If you’re tired of arguing with strangers on the Internet, try to talk with one in real life,” he quipped.