In a media blitz across legacy broadcast and left-wing publications, the former president bemoaned Facebook, Twitter and alternative media for enabling conspiracy theories like QAnon to blur the line between fact and fiction.
Mr Obama took part in a series of TV and print interviews to promote his new book, A Promised Land.
The former president said he believed that the country was entering an epistemological crisis that would break the foundation of US democracy.
"Now you have a situation in which large swaths of the country genuinely believe that the Democratic Party is a front for a paedophile ring. This stuff takes root," Mr Obama told The Atlantic.
The QAnon conspiracy theory is an intricate web of claims alleging that a deep state of cannibal paedophiles secretly pulls the strings of government. Mr Obama said he was deeply troubled by how to address half the country that just accepts what it reads online.
"The fact is that there is still a large portion of the country that was taken in by a carnival barker. I think it is the single biggest threat to our democracy. I think Donald Trump is a creature of this, but he did not create it. He may be an accelerant of it, but it preceded him and will outlast him," he said.
That "carnival barker", Mr Obama said on NPR podcast All Things Considered, began barking with the Birtherism conspiracy that claimed he wasn't born in the United States and therefore was not eligible to be president.
He said the information silos of mass media, along with Facebook, Twitter and other social media platforms, were leading people down rabbit holes.
"The denial of facts, the belief in wild conspiracy theories like QAnon getting real traction, each of us have some responsibilities to start thinking carefully about not being so gullible and just accepting whatever it is that we're seeing pop up on our phones," Mr Obama said.
On CBS This Morning, Mr Obama said that these media silos weren't just leading people down rabbit holes, they were having a real impact on the country's ability to govern and operate.
"The power of that alternative world view that's presented in the media that those voters consume, it carries a lot of weight," Mr Obama said. "It's very hard for our democracy to function if we're operating on just completely different sets of facts."
That democracy, he told 60 Minutes, was more divided than ever as issues, facts and policies didn't matter as much as identity and wanting to beat the “other guy”.
Mr Obama said democracy doesn't work without an informed citizenry, and that the government would need to regulate how that citizenry is informed and with what information.
"I think we're gonna have to work with the media and with the tech companies to find ways to inform the public better about the issues and to - bolster the standards that ensure we can separate truth from fiction," he said.
"I am somebody who does not blame the current partisanship solely on Donald Trump or solely on social media. You already saw some of these trends taking place early in my presidency. But I do think they've kept on getting worse."
Mr Obama outlined his diagnosis of the issue, and his prescription to cure it.
He said three major networks and a handful of newspapers once had a disproportionate degree of influence over the public discourse. When they lost that influence to tech companies, they lost control of the "common narrative".
“You can’t put the genie back in the bottle. You’re not going to eliminate the internet; you’re not going to eliminate the thousand stations on the air with niche viewerships designed for every political preference. Without this it becomes very difficult for us to tackle big things,” Mr Obama told The Atlantic.
He said alternative and social media companies like Facebook and Twitter had turbocharged the divide, and suggested that government oversight of what is or is not acceptable public discourse on their platforms was needed to bring the country back together.
"The degree to which these companies are insisting that they are more like a phone company than they are like The Atlantic, I do not think is tenable. They are making editorial choices, whether they’ve buried them in algorithms or not," he said.
A similar argument has been made by Mr Trump and Republicans for removing protections that tech companies receive under Section 230 of the Communications Decency Act, which designates them as platforms rather than publishers and thus protects them from legal liability for what users post on their sites.
But while Republicans argue that the companies should act like platforms and remove all censorship to keep those protections, the Democrats’ argument focuses on urging companies to act like publishers and make more editorial decisions.
"The First Amendment doesn’t require private companies to provide a platform for any view that is out there. At the end of the day, we’re going to have to find a combination of government regulations and corporate practices that address this, because it’s going to get worse. If you can perpetrate crazy lies and conspiracy theories just with texts, imagine what you can do when you can make it look like you or me saying anything on video. We’re pretty close to that now," Mr Obama said.
"If we do not have the capacity to distinguish what’s true from what’s false, then by definition the marketplace of ideas doesn’t work. And by definition our democracy doesn’t work. We are entering into an epistemological crisis."
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