People are determined to stick to their own beliefs -- no matter what fact-checkers say.
The day before the vice-presidential debate, the candidates are already prepping the public for the lies the other guy is planning to tell.
"The vice president has been studying up on (Ryan's) real positions and is prepared to call him out on his actual positions," an adviser to Joe Biden told Reuters, for example, who warned that "maybe there will be some dishonesty."
And while many resources have exposed the exaggerations and falsehoods of the first presidential debate, when we tune into Paul Ryan and Joe Biden on Thursday, most of us will still believe the rhetoric of our preferred candidate.
Why? It's human nature to seek out information that supports our own beliefs and values, said Trevor Parry-Giles, University of Maryland professor of political communications.
"It explains why people who fall on the conservative end of the political spectrum link to Fox News, whereas those on the liberal end are more likely to tune into National Public Radio or MSNBC," he said.
He's even noticed himself doing it.
"When I was listening to the debate, I was not preoccupied with fact checking the president," Parry-Giles said. "I assume the President is telling the truth, because of my politics. But to Romney, I was screaming at the screen 'That's a lie!' And on the other side, others have the same reaction to President Obama."
Our inclination to affirm our beliefs and preferences might also help explain the results of a poll by the Pew Research Center in July that showed that 30 percent of Republicans say that President Obama -- a Christian -- is a Muslim.
Not everything is as easily fact checkable as the religion of the President, Parry-Giles pointed out.
"When Paul Ryan said he ran a sub 3-hour marathon, you can empirically disprove that," he said. "But when Romney says my tax cut is not really $5 trillion -- that's fudgable. Is that over a decade? What does that really mean? When you get into the realm of fact-checking, you're assuming everything is fact checkable, and some political truths are not empirical."
Consider a candidate talking about future job projections, for example, and the truth becomes murky.
"Truth is a tough thing," said Brendan Nyhan, an assistant professor of government at Dartmouth. "We can disagree about what the right policy should be, but I'd like to hope we could agree on which facts are consistent with the best available evidence -- and keep claims that are unsupported or false out of the national debate. I hope ...or wish ... we could achieve more of a consensus on what is false."
But even that is not easy.
Corrections in the media can often backfire, Nyhan said. For one, they can perpetuate myths simply by repeating the information -- even when the negative in the statement is added, people often don't remember it. Second, consider an experiment Nyhan and a colleague conducted an experiment in 2010: Participants read a fake news story in which President Bush claimed that his tax cuts "helped increase revenues to the Treasury."
Some of the fake stories included a correction: the tax cuts "were followed by an unprecedented three-year decline in nominal tax revenues, from $2 trillion in 2000 to $1.8 trillion in 2003." All the participants were asked whether "Bush's tax cuts have increased government revenue."
Among liberals who read the corrected version, fewer respondents said the cuts increased revenue. But among conservatives who read the corrected version, over 60 percent said the cuts increased revenue -- as opposed to just over 30 percent of the conservatives who read the version without the correction.
"Once these things are out there, it's very hard to roll them back," Nyhan said. "Some people are quite determined to stick to their beliefs no matter what you tell them."
Throw in one more statistic -- that Americans who have a great deal of trust in the media is down to 40 percent, according to a Gallup poll -- and the magnitude of agreeing on a single truth becomes clear.
That's not stopping some from trying, however. Before he settles in to watch Thursday's debate, Nyhan will unplug from social media -- yes, even Twitter.
"My wife couldn't believe it, but I think there's some value in it," he said. "There's some clarity in having our own opinions and not accruing predigested opinions."