Dishonesty Has Defined the Trump Presidency. The Consequences Could Be Lasting.

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.

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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.

This is a president who casually accused a television anchor of murder, who spread the claim that Osama bin Laden is not actually dead and that President Barack Obama and Vice President Joseph R. Biden Jr. had the Navy’s SEAL Team 6 killed, who literally took a Sharpie to a map to create his own fake weather forecast and reprimanded meteorologists who dared to correct him.