The U.S. economy added 10.3 million jobs during President Obama’s second term, or 214,000 a month. This brought the official unemployment rate below 5 percent, and a number of indicators suggested that by late last year we were fairly close to full employment. But Donald Trump insisted that the good news on jobs was “phony,” that America was actually suffering from mass unemployment.

Then came the first employment report of the Trump administration, which at 235,000 jobs added looked very much like a continuation of the previous trend. And the administration claimed credit: Job numbers, Mr. Trump’s press secretary declared, “may have been phony in the past, but it’s very real now.”

Reporters laughed — and should be ashamed of themselves for doing so. For it really wasn’t a joke. America is now governed by a president and party that fundamentally don’t accept the idea that there are objective facts. Instead, they want everyone to accept that reality is whatever they say it is.

So we’re just supposed to believe the president if he says, falsely, that his inauguration crowd was the biggest ever; if he claims, ludicrously, that millions of votes were cast illegally for his opponent; if he insists, with no evidence, that his predecessor tapped his phones.

And it’s not just about serving one man’s vanity. If you want to see how this attitude can hurt millions of people, consider the state of play on health care reform.

Obamacare has led to a sharp decline in the number of Americans without health insurance. You can argue that the decline should have been even sharper, that there may be troubles ahead, or that we should have done better. But the reality of the law’s achievement shouldn’t be in question, and you should worry about the consequences of Trumpcare, which would drastically weaken key provisions.

Republicans, however, are in denial about recent gains. The president of the Heritage Foundation dismisses the positive effects of the Affordable Care Act as “fake news.” In Louisville over the weekend, Vice President Mike Pence declared that “Obamacare has failed the people of Kentucky” — this in a state where the percentage of people without insurance fell from 16.6 to 7 percent when the law went into effect.

And as for the likely impacts of Trumpcare — well, they literally don’t want to know.

When Congress is considering major legislation, it normally waits for the Congressional Budget Office to “score” the proposal — to estimate its effects on revenues, outlays and other key targets. The budget office isn’t always right, but it has a very good track record compared with other forecasters; even more important, it has always been scrupulous about avoiding partisanship, and therefore acts as an important check on politically motivated wishful thinking.

But Republicans rammed Trumpcare through key committees, literally in the dead of night, without waiting for the C.B.O. score — and they have been pre-emptively denouncing the budget office, which is likely to find that the bill would cause millions to lose health coverage.

The truth is that while the office got some things wrong about health reform, on the whole it did pretty well at projecting the effects of a major new bill — and far better than the people now attacking it, who predicted disasters that never happened. And whatever criticisms one may have of its forthcoming score, it will surely be better than the ludicrous claim of Tom Price, the secretary of health and human services, that “nobody will be worse off financially” as a result of a plan that drastically cuts subsidies and raises premiums for millions of Americans.

But this isn’t really about whose analyses of health policy are most likely to get it right. It’s about Trump and company attacking the legitimacy of anyone who might question their assertions.

The C.B.O., in other words, is in the same position as the news media, which Mr. Trump has declared “enemies of the people” — not, whatever he may say, because they get things wrong, but because they dare to challenge him on anything.

“Enemy of the people” is, of course, a phrase historically associated with Stalin and other tyrants. This is no accident. Mr. Trump isn’t a dictator — not yet, anyway — but he clearly has totalitarian instincts.

And much, perhaps most, of his party is happy to go along, accepting even the most bizarre conspiracy theories. For example, a huge majority of Republicans believe Mr. Trump’s basically insane charges about being wiretapped by President Obama.

So don’t make the mistake of dismissing the assault on the Congressional Budget Office as some kind of technical dispute. It’s part of a much bigger struggle, in which what’s really at stake is whether ignorance is strength, whether the man in the White House is the sole arbiter of truth.