Part of the problem is that these companies have largely abrogated the responsibility of moderating the content that appears on their platforms, instead relying on rule-based algorithms to determine who sees what. Facebook, for instance, previously had a team of trained news editors who chose which stories appeared in its trending topics section, a huge driver of traffic to news stories. But it disbanded the group and instituted an automated process last year, after reports surfaced that the editors were suppressing conservative news sites. The change seems to have made the problem worse — earlier this year, Facebook redesigned the trending topics section again, after complaints that hoaxes and fake news stories were showing up in users’ feeds.

There is also a labeling issue. A Facebook user looking for news about the Las Vegas shooting on Monday morning, or a Google user searching for information about the wrongfully accused shooter, would have found posts from 4Chan and Sputnik alongside articles by established news organizations like CNN and NBC News, with no obvious cues to indicate which ones came from reliable sources.

More thoughtful design could help solve this problem, and Facebook has already begun to label some disputed stories with the help of professional fact checkers. But fixes that require identifying “reputable” news organizations are inherently risky because they open companies up to accusations of favoritism. (After Facebook announced its fact-checking effort, which included working with The Associated Press and Snopes, several right-wing activists complained of left-wing censorship.)

The automation of editorial judgment, combined with tech companies’ reluctance to appear partisan, has created a lopsided battle between those who want to spread misinformation and those tasked with policing it. Posting a malicious rumor on Facebook, or writing a false news story that is indexed by Google, is a nearly instantaneous process; removing such posts often requires human intervention. This imbalance gives an advantage to rule-breakers, and makes it impossible for even an army of well-trained referees to keep up.

But just because the war against misinformation may be unwinnable doesn’t mean it should be avoided. Roughly two-thirds of American adults get news from social media, which makes the methods these platforms use to vet and present information a matter of national importance.

Facebook, Twitter and Google are some of the world’s richest and most ambitious companies, but they still have not shown that they’re willing to bear the costs — or the political risks — of fixing the way misinformation spreads on their platforms. (Some executives appear resolute in avoiding the discussion. In a recent Facebook post, Mark Zuckerberg reasserted the platform’s neutrality, saying that being accused of partisan bias by both sides is “what running a platform for all ideas looks like.”)

The investigations into Russia’s exploitation of social media during the 2016 presidential election will almost certainly continue for months. But dozens of less splashy online misinformation campaigns are happening every day, and they deserve attention, too. Tech companies should act decisively to prevent hoaxes and misinformation from spreading on their platforms, even if it means hiring thousands more moderators or angering some partisan organizations.

Facebook and Google have spent billions of dollars developing virtual reality systems. They can spare a billion or two to protect actual reality.