Columnist

A common defense of President Trump points to the positive things he has done from a Republican perspective — his appointment of Justice Neil M. Gorsuch and other conservative judges, his pursuit of the Islamic State, his honoring of institutional religious freedom. This argument is not frivolous. What frustrates is the steadfast refusal among most Republicans and conservatives to recognize the costs on the other side of the scale.

Chief among them is Trump's assault on truth, which takes a now-familiar form. First, assert and maintain a favorable lie. Second, attack and discredit sources of opposition. Third, declare victory based on power or applause. So, Trump claimed that Florida Democratic Rep. Frederica Wilson's account of his conversation with a Gold Star widow was "totally fabricated." (Not true.) Wilson, after all, is "wacky." (Not relevant.) And Trump won the interchange because Wilson is "killing the Democrat Party." (We'll see.)

The pattern is invariable. President Barack Obama is a Kenyan; the Mexican government deliberately dumps criminals across the border; "thousands and thousands" of people in New Jersey celebrated the 9/11 attacks ; Texas Republican Sen. Ted Cruz's father consorted with Lee Harvey Oswald; vaccination schedules can be tied to autism; Obama was "wiretapping" Trump Tower during the presidential campaign; Obama asked British intelligence to spy on Trump; at least 3 million immigrants voted illegally in the 2016 election. Any source that disputes Trump is personally defamed or dismissed as "fake news." And how is truth ultimately adjudicated? "The country believes me," Trump said earlier this year. "Hey, I went to Kentucky two nights ago. We had 25,000 people." Confronted by a reporter about his routine deceptions, Trump answered, "I can't be doing so badly, because I'm president and you're not."

Thirty years ago, University of Chicago professor Allan Bloom's "The Closing of the American Mind" began with the words: "There is one thing a professor can be absolutely certain of: Almost every student entering the university believes, or says he believes, that truth is relative." Bloom found this deeply problematic, because the ability to determine truth from falsehood, right from wrong, is essential to personal flourishing and civic health. I wonder what Bloom would make of a political philosophy in which truth is determined by 25,000 screaming partisans and reality is a function of fabulism. Conservatives were supposed to be the protectors of objective truth from various forms of postmodernism. Now they generally defend our thoroughly post-truth president. Evidently we are all relativists now.

Not quite all. Some of us still think this attack on truth is a dangerous form of political corruption. The problem is not just the constant lies. It is the dismissal of reason and objectivity as inherently elitist and partisan. It is the invitation to supporters to live entirely within Trump's dark, divisive, dystopian version of reality. It is the attempt to destroy or subvert any source of informed judgment other than Trump himself. This is the construction of a pernicious form of tyranny: a tyranny over the mind.

Not that the attempt is fully conscious. Some of this preference for deception may be the result of pathological compulsions. Some of it is surely the intuitive use of trolling to draw attention away from scandals and failures. Some of it may be a strategy to discredit contending sources of truth in Trump's upcoming public battle with special counsel Robert S. Mueller III.

But here is the cost. When there is no objective source of truth — no commonly agreed upon set of facts and rules of argument — political persuasion becomes impossible. There is no reasoned method to choose between one view and another. The only way to settle political disputes is power — determined by screaming mobs or because "I'm president and you're not." Politics becomes an endless battle of true believers, conditioned to distrust and dismiss every bit of evidence that does not confirm their preexisting views. The alternative to reasoned discourse is the will to power.

This is the frightening direction of Trumpism. It is the corruption that good men such as White House Chief of Staff John F. Kelly are enabling. And it is a source of enduring shame for many conservatives. "Sycophancy toward those who hold power," said Bloom, "is a fact in every regime, and especially in a democracy, where, unlike tyranny, there is an accepted principle of legitimacy that breaks the inner will to resist. . . . Flattery of the people and incapacity to resist public opinion are the democratic vices, particularly among writers, artists, journalists and anyone else who is dependent on an audience."

Exactly how the conservative movement was broken.

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