During a virtual town hall event last week, in response to a question about how he planned to appeal to young voters, Joe Biden harkened back to his experience as a university professor following his departure from the United States Senate:

When I left the United States Senate I became a professor at the University of Pennsylvania … and the University of Delaware has the Biden school as well, so I’ve spent a lot of time … on campus with college students.”

It’s fair to say many viewers probably drew the most obvious conclusion: that the former vice president had left public office (presumably the vice presidency, rather than the Senate as Biden had said) and taken up work lecturing to young people at the University of Pennsylvania.

The problem? Biden never actually taught at Penn.

As the school’s campus newspaper reported in 2017, the former Vice President’s appointment initially led some students and faculty to believe he was going to be working as an instructor but Biden spokesperson Kate Bedingfield (who currently serves in a senior role on his campaign) soon confirmed that he would “not,” in fact, “be teaching classes” after all. Last year, the Philadelphia Inquirer reported that Biden was paid more for the professorship than he’d made as vice president — $371,159 in 2017 plus $540,484 in 2018 and early 2019 — for what it called “a vaguely defined role that involved no regular classes and around a dozen public appearances on campus, mostly in big, ticketed events” (the average salary for a Penn professor, for comparison, was $217,411 in 2017-18).

In the most charitable interpretation, Biden was merely taking some liberty with regard to his role at Penn in order to underscore his sympathy for college students. Even this, of course, is quite a stretch: giving ticketed speeches to large crowds certainly doesn’t make you a professor in the sense most would understand it, even if the former Vice President’s role did technically carry the title. Moreover, having visited a campus a handful of times over the course of a few years hardly constitutes a prolonged exposure to college life as it’s experienced by average students – which was, after all, the very point it seems Biden was attempting to make.

In this exposition of his answer, the former Vice President was as good as holding up a small number of visits to a campus in Pennsylvania as evidence of his street cred with the young — engaging in some pretty egregious hyperbole, though not exactly lying. But, as it turns out, he said something very similar at an event in Georgia, South Carolina last month as part of a lengthy (and not, it must be said, particularly coherent) answer to a question about schools and education policy:

When I got out of the United State Senate, instead of taking a Wall Street job – and they’re not bad, I’m not making them bad – but instead of doing the things that I never did before, I figured I wasn’t going to change all these years from what I was comfortable doing. So I became a teacher. I became a professor.

Once again, Biden presumably meant to refer to the Vice Presidency rather than the Senate (which he left in 2009, to assume the Vice Presidency). Nonetheless, the remark appears to be a more explicit version of the falsehood from his virtual townhall event this week, coming as it did with the addendum “I became a teacher.”

By Biden’s standards, all this is actually a comparatively trivial bending of the truth.

Though hastily forgotten, if indeed many noticed it at all, Biden last summer spun an elaborate tale about visiting Afghanistan to honor a Naval officer who he said had rappelled down a ravine while under fire to retrieve the body of a fellow soldier. “This is God’s truth,” Biden said, “My word as a Biden.” But as the Washington Post, having investigated the story, put it at the time:

… almost every detail in the story appears to be incorrect … it appears as though the former vice president has jumbled elements of at least three actual events into one story of bravery, compassion and regret that never happened … The upshot: In the space of three minutes, Biden got the time period, the location, the heroic act, the type of medal, the military branch and the rank of the recipient wrong, as well as his own role in the ceremony.

More recently, Biden claimed several times to have been “arrested” in the 1970s while “trying to see” Nelson Mandela in prison, a claim that seems to have been entirely fabricated. During a separate town hall event this month Biden also insisted he’d cosponsored the Endangered Species Act (he didn’t). Over the course of the campaign, Biden has elsewhere lied about the circumstances surrounding his vote for the 2003 invasion of Iraq and revived an old falsehood that he “came out of” the Civil Rights Movement.

None of these incidents seem to have done visible harm to his political prospects or made their way into the broader campaign narrative even when they have registered in mainstream publications. At time of writing no mainstream news outlet has mentioned Biden’s latest untruth — now made on at least two occasions — that he worked as a professor after leaving public office. Instead, it’s appeared in conservative outfits like Fox News, the Daily Caller, Washington Times, and the Washington Examiner, all of which have reported regularly on the former vice president’s well-established proclivity for lying.

This observation isn’t made to praise right-wing news outlets, but rather to point out a wider problem with America’s media ecosystem and help answer the most pressing and obvious question in relation to all of this: namely, why so few prominent liberals (or primary voters) seem to know or care that the Democratic frontrunner has spent the past year or so lying through his teeth.

Biden’s 1988 presidential campaign, after all, was derailed in a matter of days as a result of similar (and in some cases, identical) falsehoods alongside a plagiarism scandal that saw him lifting oratory almost word-for-word from British Labour leader Neil Kinnock. Moreover, the importance of truth and facts, especially when it comes to claims made by politicians, is supposed to be a major concern of the Trump era — particularly among liberal audiences. In light of all this, it’s worth pondering why Biden’s lies have received so little attention outside the conservative media and why they have never really grown into a major story like the one that ended his presidential ambitions just over three decades ago.

Most people, even many of those who harbor deep partisan commitments, intuitively recognize that America’s media landscape is dangerously siloed: that is, liberals and conservatives alike consume content specifically cooked up to satiate their ideological appetites and reinforce whatever narratives they’ve already internalized. Fewer really understand how uniquely destructive this is to democratic politics beyond the oft-invoked complaint that media partisanship coarsens discourse and prevents Americans from using their indoor voices.

The effect is actually much worse than that given the extent to which many media consumers ultimately come to inhabit different realities curated exclusively for whatever market niche they happen to belong to. As journalist Matt Taibbi writes in his book Hate Inc.:

People need to start understanding the news not as “the news,” but as … an individualized consumer experience — anger just for you. This is not reporting. It’s a marketing process designed to create rhetorical addictions and shut down any non-consumerist doors in your mind. This creates more than just pockets of political rancor. It creates masses of media consumers who’ve been trained to see in only one direction, as if they had been pulled through history on a railroad track, with heads fastened in blinders, looking only one way.

One particularly dangerous implication of this process is that it’s often, and sometimes exclusively, right-wing media outlets that take up stories of Democratic corruption or scandal (and vice versa for liberal outlets vis a vis Republicans). If Fox News or Breitbart reports a story, for example, there’s a good chance many liberals will never hear about it. If they do, it will instantly lose all credibility by virtue of association with the depraved and frequently misleading media mouthpieces of the Right and potentially benefiting their partisan foes — even if it happens to be true.

America’s bifurcated media structure, founded on a corporate business model that has effectively commodified partisan infotainment, is among the major reasons Biden’s cavalcade of lies hasn’t really become a story among liberals. Some simply haven’t heard about them. Many others, meanwhile, are liable to greet the reports that do emerge with a perfunctory shrug (who among us, after all, is going to trust a story that originated on Fox News?) or worse, dismiss them all as part of a right-wing conspiracy even when they turn out to be credible or demonstrably true.

More than anything else, this epistemological loophole explains how it is that partisan liberals are so often able to ignore or even contravene their own espoused standards in the face of information that may harm their side. It’s why so few regularly incensed by Donald Trump’s untruths seem to care that a former Democratic vice president has a well-documented history of making things up and why there’s been virtually no outrage at his campaign’s hiring of a former advisor to Harvey Weinstein. And it’s why, in the coming days, many will probably find it alarmingly easy to dismiss and ignore a woman who has come forward with an allegation against him far more serious than a tall tale about a no-show professorship at the University of Pennsylvania.