The same criticism has also engulfed other social media companies such as Twitter, which on Friday said it was emailing notifications to 677,775 people in the United States that they had interacted with Russian propaganda accounts around the time of the 2016 election.
For publishers, Facebook’s new ranking system raised immediate concerns, including whether crowdsourcing users’ opinions on trustworthiness might be open to manipulation.
“It is absolutely a positive move to start to try to separate the wheat from the chaff in terms of reputation and use brands as proxies for trust,” said Jason Kint, the chief executive of Digital Content Next, a trade group that represents entertainment and news organizations, including The New York Times. “But the devil’s in the details on how they’re going to actually execute on that.”
He continued, “How does that get hacked or gamed? How do we trust the ranking system? There’s a slew of questions at this point.”
The new system could also potentially favor publishers who are partisan. Facebook users, asked to rank which news they most trust, could choose sites that speak most clearly to their personal beliefs, in effect reducing the prominence of publishers who try to maintain an objective tone.
David Kaye, the United Nations’ Special Rapporteur on freedom of expression, said that Facebook would probably face more difficult questions as it rolled out the new ranking program globally.
“What will happen in situations where a community determines that a news source is trustworthy, but that news source is censored, or illegal, in that country?” asked Mr. Kaye, noting that in many parts of the world, governments controlled all official news channels while independent news sources were outlawed or forced to publish pseudo-anonymously.
In the past, he added, Facebook has abided by local rules where it operates abroad.
“What will Mark Zuckerberg do when the needs of the community, in what it determines is trusted news, are different from what the government determines. Who will Facebook side with?” said Mr. Kaye.
Raju Narisetti, the chief executive of the Gizmodo Media Group, the unit of Univision that operates Jezebel and other sites, said there was a “great irony” that Facebook, which has traditionally left decision up to an algorithm that incorporates the behaviors of its members, would open the decision-making to its users on such a matter. He added that the user-generated ranking system “is a massive abdication of its social responsibility, as a vital platform, to be a good custodian of the Fourth Estate globally.”
Other experiments that Facebook has tried with news in the past have sometimes gone awry or had unintended consequences. For example, a recent test to remove all news publishers from the News Feed and to place them under a separate tab in six countries, including Bolivia and Slovakia, yielded an unexpected result of magnifying the amount of fake news on the platform.
In his post on Friday, Mr. Zuckerberg said the newest change “will only shift the balance of news you see towards sources that are determined to be trusted by the community.”
Facebook said news would be prioritized according to the new ranking system starting Monday, before expanding globally. Some Facebook users have already been asked to rank the trustworthiness of news sites which appear on the social network. In one survey, people were asked if they recognized a number of websites and then asked, ““How much do you trust each of these domains?” They were able to choose from a range of answers, including entirely, a lot, somewhat, barely and not at all.
The Silicon Valley company said it would continue polling users to refine and select which news outlets garnered the most trust. It declined to say how many people were polled or which news outlets they were asked about.
“As part of our ongoing quality surveys, we asked a diverse and representative sample of Facebook users across the U.S. to gauge their familiarity with, and trust in, sources of news,” said Todd Breasseale, a Facebook spokesman. “We boost links from sources with high trust scores and demote links from sources with low trust scores.”
Mr. Zuckerberg has been moving Facebook toward taking more responsibility for what shows up on the social network, especially after the criticism over the 2016 election and the interference by Russian agents. Earlier this month, he described his 2018 goals as including “making sure that time spent on Facebook is time well spent.”
In Friday’s post, he hinted that ranking the credibility of news sources was just one step, with more potential changes to come.
”I’ve asked our product teams to make sure we prioritize news that is trustworthy, informative, and local,” he wrote. “And we’re starting next week with trusted sources.”