In an off-the-record speech at a sports policy conference at MIT, former president Barack Obama expressed concern with how social media has served to divide the American people.

Reason, a libertarian magazine, obtained an audio recording of Obama’s speech. In it, Obama noted that Americans are essentially living in “entirely different realities,” that don’t just differ in opinion, but also in fact.

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He called the phenomenon a “Balkanization of our public conversation.” Quoting Daniel Patrick Moynihan, Obama noted that we no longer live in a society where “Everyone is entitled to his own opinion, but not to his own facts.”

And the cause isn’t just Russian-inspired bots and fake news, according to the ex-president. “This is Fox News vs. The New York Times editorial page,” Obama said. The two “do not describe the same thing. In some cases, they don’t even talk about the same thing.”

Social media, in turn, exacerbates this problem, as the platforms have effectively become media companies, dealing in content distribution. While these platforms have a “hugely powerful potential for good,” they are also “just a tool,” one which can be used by the likes of ISIS and neo-Nazis.

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Therefore, Obama argued, platforms like Google and Facebook and even Twitter have a responsibility to look at their business model and work toward creating more of a “common conversation.” They must recognize that “they are a public good as well as a commercial enterprise,” as “they’re not just an invisible platform, they’re shaping our culture in powerful ways,” he continued.

Failing to do so, “it is very difficult to figure out how democracy works over the long term,” Obama said.