The disconnect has tangible consequences. Republicans who support Mr. Trump are more likely to dismiss the threat of the virus in surveys and less likely to wear masks or maintain social distance. A poll last week by Axios and Ipsos found only half of Americans could correctly respond to six factual questions about the virus, indicating how far misinformation linked to reckless behavior has pervaded the public.
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Scientists have concluded that 130,000 lives could be saved in the United States in the coming months if there was universal mask wearing. But Mr. Trump mocks facial coverings and disparages medical experts, undercutting their credibility with the public, most notably Dr. Anthony S. Fauci, the federal government’s chief epidemiologist who now has to have a security detail after vilification by the president and his allies. With views of the virus increasingly falling along party lines, many Americans express distrust over a possible new vaccine, which could lead to widespread resistance to inoculation.
Beyond the health crisis, Mr. Trump’s successor, whether next year or in five years, could face a broader crisis in faith, challenged to re-establish credibility with overseas allies and adversaries, while presiding over a country where truth has been broken down into tribes and much of the public has been conditioned to distrust institutions of all sorts.
Mr. Trump has spent four years telling Americans not to trust anyone other than him, whether it be public health experts, scientists, journalists, judges, career government officials, investigators, generals, intelligence agencies, election officials and even mail carriers. “Just remember,” he told a crowd one summer, “what you are seeing and what you are reading is not what’s happening.”
Trust, once lost, is hard to restore. “We know a lot about the delegitimation of democratic institutions over the last two centuries,” Ms. Rosenblum said. “But we know nothing about how you relegitimate institutions that have lost their main value and authority for an awful lot of people. That’s the real question.”
Dishonesty has been a defining hallmark of the Trump presidency. The sheer volume of untruths, both petty and profound, has been cataloged and quantified time and again, the subject of a shelf full of books and endless hand-wringing over the “post-truth” world.