The Washington conventional wisdom presupposes a kind of symmetry between our polarized political parties. Liberals and conservatives, it is said, live in separate bubbles, where they watch different television networks, frequent different Web sites, and absorb different realities. The implication of this view is that both sides resemble each other in their twisted views of reality. Rachel Maddow and Sean Hannity, in other words, represent two sides of the same coin.

This view is precisely wrong, according to a provocative new book by Yochai Benkler, Robert Faris, and Hal Roberts that will be published next month by Oxford University Press. The book’s title, “Network Propaganda: Manipulation, Disinformation, and Radicalization in American Politics,” is a mouthful, but the book’s message is almost simple. The two sides are not, in fact, equal when it comes to evaluating “news” stories, or even in how they view reality. Liberals want facts; conservatives want their biases reinforced. Liberals embrace journalism; conservatives believe propaganda. In the more measured but still emphatic words of the authors, “the right-wing media ecosystem differs categorically from the rest of the media environment,” and has been much more susceptible to “disinformation, lies and half-truths.”

“Network Propaganda” is an academic work at the crossroads of law, sociology, and media studies. Benkler is a law professor at Harvard and a co-director of the university’s Berkman Klein Center for Internet and Society, where Faris and Roberts both conduct research. The book is not a work of media criticism but, rather, of data analysis—a study of millions of online stories, tweets, and Facebook-sharing data points. The authors’ conclusion is that “something very different was happening in right-wing media than in centrist, center-left and left-wing media.” Accordingly, they wrote the book “to shine a light on the right-wing media ecosystem itself as the primary culprit in sowing confusion and distrust in the broader American ecosystem.”

The core of the book is the study of how that right-wing ecosystem works. According to the authors, false stories are launched on a series of extreme Web sites, such as InfoWars (the home of Alex Jones), “none of which claim to follow the norms or processes of professional journalistic objectivity.” Those stories are then transmitted to outlets such as Fox News and the Daily Caller, which, according to the authors, “do claim to follow journalistic norms,” but often fail in that function when it comes to tales from the Web sites. Notably, the authors write, “this pattern is not mirrored on the left wing.” There are no significant Web sites on the left that parallel the chronic falsity of those on the right, and the upstream sources do follow traditional journalistic standards, and serve “as a consistent check on the dissemination and validation of the most extreme stories when they do emerge on the left, and have no parallels in the levels of visibility or trust that can perform the same function on the right.”

How do the authors prove their case? The most persuasive sections of the book concern case studies of stories that did, or did not, go viral in these politically disconnected universes. Consider two stories that emerged over the course of the 2016 Presidential campaign: in one, Bill and Hillary Clinton were involved in acts of pedophilia, which included the abuse of Haitian refugee children and visits to an orgy island—preposterous claims for which there was no shred of evidence. In the other, Donald Trump supposedly raped a thirteen-year-old girl, in 1994—something that he was accused of in a lawsuit filed in 2016. At first, there was great interest on the left in the Trump story. There were five times as many Facebook shares of the most widely shared article about it (1.25 million) as of the most widely shared story about the imagined Clinton pedophilia. But all that chatter was followed by near silence in the liberal and mainstream media, as the story failed to survive the most basic fact-checking scrutiny. (Trump denied the allegations; the lawsuit was subsequently dropped, refiled, and dropped again.) As the authors write, “the presence and attention of both journalists and readers to diverse sites was enough to enforce a hard constraint on the ability to disseminate politically affirming falsehoods.”

The Clinton orgy-island story met a very different fate in the right-wing media, which pushed versions of it over the course of the campaign. (Fox News initially ran several segments that raised the topic of the “Lolita Express.”) The dynamic on the right, the authors found, “rewards the most popular and widely viewed channels at the very top of the media ecosystem for delivering stories, whether true or false, that protect the team, reinforce its beliefs, attack opponents, and refute any claims that might threaten ‘our’ team from outsiders.” Referring to the orgy-island story, the authors note that “not one right-wing outlet came out to criticize and expose this blatant lie for what it was. In the grip of the propaganda feedback loop, the right-wing media ecosystem had no mechanism for self-correction, and instead exhibited dynamics of self-reinforcement, confirmation, and repetition so that readers, viewers and listeners encountered multiple versions of the same story, over months, to the point that both recall and credibility were enhanced.”

“Network Propaganda” does refute some favorite liberal explanations for the results of the 2016 election. The authors acknowledge the sustained efforts of fake-news Web sites from the nations of the former Soviet Union, as well as the work of Russian hackers and bots, but they are not convinced that their impact was significant. They also downplay the influence of the Facebook-targeting work done by Cambridge Analytica, and they write that Facebook’s news-feed algorithm was of only modest importance. Rather, it was the feedback loop of right-wing quasi-journalism that had the most impact—and that hypothesis has profound implications not only for the study of the recent past but also for predictions about the not-so-distant future.