Why objectively false things in politics continue to be believed

“Everyone is entitled to his own opinion, but not his own facts,” goes the saying — one that now seems like a relic of simpler times.

Today, President Donald Trump is sticking with his own facts — his claim that the Obama administration wiretapped him during the election — in the face of testimony to the contrary by the FBI director, James B. Comey.

When asked about the accusations Trump had made on Twitter, Comey told a Senate committee on Monday, “I have no information that supports those tweets, and we have looked carefully inside the FBI.”

Other government authorities have come to similar conclusions. But press secretary Sean Spicer said after the hearing that Trump stands by his wiretap allegations despite Comey’s testimony.

Trump’s claims may appear to his opponents to have been embarrassingly debunked. But social science research suggestsTrump’s alternative version of reality may appeal to his supporters.

Partisan polarization is now so extreme in the United States it affects the way people consume and understand information — the facts they believe, and what events they think are important. The wiretapping allegations could well become part of a partisan narrative too powerful to be dispelled.

Trump, perhaps unconsciously, has grasped a core truth of modern politics: that voters tend to seek out information that fits the story they want to believe, usually one in which members of the other party are the bad guys.

Since the 1980s, Americans have been reporting increasingly negative opinions about the opposing party. Partisanship, and particularly “negative partisanship,” the rejection of the opposing party, has now become a kind of tribal identity that shapes how people define themselves and others, according to Sean Westwood, a professor at Dartmouth College who has studied partisan polarization. “It drives people to support their team at any cost, and oppose the opposing team at any cost,” he said.

This partisan polarization affects the way Americans of all political stripes consume information. People are more likely to believe stories that come from their side of the political divide, particularly if an authority figure vouches for them. And they are more likely to share news with their preferred slant as a way of showing they are good members of their political tribe.

Trump’s wiretap claim is particularly likely to appeal to that partisan dynamic. At its core, it is a story about Barack Obama being fundamentally untrustworthy, perhaps even dangerous to the country. Trump’s supporters, who already are more likely to believe that basic narrative, may be more likely to accept his wiretap claims.

Sticking to his version of events probably will strengthen Trump’s base, said John Sides, a political-science professor at George Washington University who studies political communication.

“At the end of the day, those people are going to put a floor under your approval ratings,” he said.

But, he cautioned, the constant cycles of controversy are preventing him from establishing the broader appeal required to assure a successful presidency.

One might expect facts would convince people Trump’s claim was baseless, but other political myths have proven remarkably robust to the sort of debunking Comey provided.

For instance, Trump disavowed the “birther” myth in September 2016, conceding Obama was in fact born in the United States. There was an increase afterward in the number of voters who said they believed Obama was born here, but polling by Morning Consult suggests part of that effect has already faded. In September, it found that 62 percent of registered voters said they believed Obama had been born in the United States, but in a follow-up poll early this month, that number had dropped to 57 percent.

This decline cannot be attributed simply to partisan bias; it occurred among both Democrats (who went to 77 percent from 82 percent) and Republicans (down to 36 percent from 44 percent). Over time, people may simply forget the contrary evidence they have heard and fall back on their old beliefs.