There is truth, and then there is everything that is not truth. The Trump administration is betting its continued existence on its capacity to blur that important distinction, to claim that truth is unknowable and thus not worth the effort to discover, and that with truth unknowable, we are freed to believe whatever we prefer to believe, the actual truth be damned.

This is how it works:

In an appearance on “Meet the Press” Sunday, Trump attorney Rudy Giuliani told America that when Donald Trump Jr. set up a meeting on June 9, 2016 to collect dirt on Hillary Clinton, he had no idea that the woman offering the dirt was Russian or that she was being sent by the Russian government.

“She didn’t represent the Russian government, she’s a private citizen. I don’t even know if they knew she was Russian at the time. All they had was her name,” Giuliani said. “All they knew is that a woman with a Russian name wanted to meet with them. They didn’t know she was a representative of the Russian government and indeed, she’s not a representative of the Russian government.”

Contrast that statement to the email that got Donald Trump Jr. so excited about setting up that meeting:

“Emin (Agalarov, a Russian friend of Trump) just called and asked me to contact you with something very interesting.

The crown prosecutor of Russia met with his father Aras this morning and in their meeting offered to provide the Trump campaign with some official documents and information that would incriminate Hillary and her dealings with Russia and would be very useful to your father.

This is obviously very high level and sensitive information but is part of Russia and its government's support for Mr. Trump.”

In a followup email trying to nail down the time and place of the meeting, Trump Jr. is again told:

“Emin asked that I schedule a meeting with you and The Russian government attorney who is flying over from Moscow for this Thursday.”

A Russian government attorney, sent by a top Russian official, was bringing official Russian documents as “part of Russia and its government's support for Mr. Trump,” yet Trump Jr. had no idea the Russian government was involved?

Obviously, Giuliani is lying, and I think it’s the obviousness of the lie that tells us the most. Giuliani knows full well that those contradictory emails exist; he knows full well what they say. He knows that Trump Jr. responded to the offer with an email of his own, replying that “if it’s what you say I love it especially later in the summer.”

So why spin such an obvious lie? Why make an argument that Giuliani knows is not true, that he knows can be easily disproved by documentary evidence?

Because he does not care. He understands that a significant number of Americans have retreated into a post-truth age in which the truth doesn’t matter and does not even exist anymore. All he needs to do is create an alternative narrative, backed by alternative “facts” in an alternative world, that Trump defenders can choose to enter and find comfort and reassurance, protected against the intrusion of facts.

In fact, later in the interview, Giuliani makes that strategy explicit.  In an exchange with host Chuck Todd, Giuliani tries to explain why Trump is balking about testifying before a grand jury.

GIULIANI: “I am not going to be rushed into having him testify so that he gets trapped into perjury. And when you tell me that, you know, ‘he should testify because he’s going to tell the truth and he shouldn’t worry,’ well that’s so silly because it’s somebody’s version of the truth. Not the truth. He didn’t have a, a conversation... “

TODD: “Truth is truth. I don’t mean to go like --”

GIULIANI: “No, it isn’t truth. Truth isn’t truth.”

In the court of public opinion, Trump and Giuliani believe that they can get away with such nonsense. Indeed, the record shows that they already have done so, repeatedly, and with very little cost to their credibility.

Initially, the Trump election operation had asserted in blunt language that it had had zero contacts with Russians during the campaign, and it expressed outrage at any suggestion otherwise. Once the Trump Tower meeting and dozens of other such contacts came to light, they retreated to a second line of defense, claiming that the Trump Tower meeting had been about Russian adoptions, not about getting dirt on Clinton. When that was exposed as a lie, the campaign claimed that President Trump had played no role in drafting that fake adoption story as a coverup. That too was false;  Trump’s attorneys now concede that the president did indeed dictate that false claim, which they try to brush away with the explanation that “facts develop over time.”

Again, in the court of public opinion, where people can choose to believe what they want to believe, Trump can get away with such an approach. A court of law, however, operates by very different rules. In a court of law, this notion that “the truth isn’t truth” doesn’t wash. The central notion of our legal system is that truth does exist, and that as rational creatures wanting justice we are obligated to seek such truth. That’s why it requires witnesses to tell the truth, the whole truth and nothing but the truth.

In a court of law, then, lies and the liars who tell them are sifted out.  Various versions of the truth might be proposed, but each is tested against the evidence and testimony until one version of the truth is accepted. And unlike the court of public opinion, in the court of law there are grim consequences for lying. So while Giuliani might safely tell his cock-and-bull story about the Trump Tower meeting on national TV, presumably he would never advise Trump Jr. to go into a courtroom and try to sell that nonsense to a jury, because it would be a slam-dunk case of perjury.

Likewise, if President Trump claims that he and James Comey never discussed “going easy” on Michael Flynn, but Comey says they did, the legal system has long-established, well-tested means of determining which of them is the liar.  And it is that systematic, disciplined, rule-driven process of determining truth that Giuliani and the rest of the Trump legal team need so desperately to avoid.