All the way back in 2005, Donald Trump stumbled on what would become the fundamental operating principle of today's Republican Party. And we have Billy Bush to thank for bringing it to light.

The shamed former NBC host re-emerged this week, after a year out of the public eye in which he claims to have conducted rigorous soul-searching over the notorious Access Hollywood tape. Bush wrote an op-ed for The New York Times looking back on his role in President Trump's 2005 confession, revealed in the closing weeks of the 2016 campaign, and said that that on one occasion, when "I called him out for inflating his ratings" on The Apprentice, the future president replied, "People will just believe you. You just tell them and they believe you."

At that moment, it might have seemed like the sentiment of an amoral sociopath, one who had learned from long experience that if you're rich enough and brazen enough, you can get away with behavior that ordinary people feel qualms about. But it would also turn out to be a profound insight into contemporary politics, one that the Republican Party has now adopted as one of its fundamental principles.

Not that the GOP was afraid to lie before it raised Trump up as its champion. But they've decided that they really can say anything, no matter how ridiculous, obviously false, or morally repellent it might be. People — or at least some people — will just believe them, and even change their own beliefs to match those of their political leaders.

Let's look at a few vivid recent examples.

For starters, Roy Moore. For a while, the party seemed genuinely torn over supporting someone who thinks homosexuality should be illegal, Muslims should be banned from serving in Congress, and judges can ignore the law if they think it's what scripture commands — and oh yeah, who has been credibly accused by multiple women of everything from hitting on them to outright sexual assault when they were teenagers, allegations that are backed up not only by people they knew at the time but by people who were acquainted with Moore as a man in his 30s who was known around town for dating high school girls and hanging around the local mall to hit on them.

But Republicans are torn no longer. President Trump has enthusiastically endorsed Moore, Mitch McConnell now says the people of Alabama should "make the call" as to whether Moore should serve in the Senate (after opposing him before), and the Republican National Committee has recommitted itself to helping his candidacy. As for all that talk about not seating him in the Senate, that's no longer operative. As Sen. Orrin Hatch (R-Utah) said when asked if there should be an Ethics Committee investigation of the charges against Moore, "Frankly if he gets elected, that will settle an awful lot of the questions."

Perhaps most colorfully, Moore's spokesperson went on television to respond to the charges of all the women who have accused Moore of misconduct. "We need to make it clear," she said, "that there's a group of non-accusers, that have not accused the judge of any sexual misconduct or anything illegal." So when you're in the voting booth, ask yourself: Did Roy Moore personally molest me or a member of my family? If the answer is no, that's good enough for Republicans in Alabama.

Next up, we have the Russia scandal. President Trump's attorney said this week that his client can't possibly be guilty of obstruction of justice, despite the mounting evidence that he is, for the convenient reason that the president is the chief law enforcement officer of the government, and therefore anything he does with regard to the pursuit of justice can't obstruct justice. To call that idea "Nixonian" is generous, but this was the same lawyer who claimed that he wrote a tweet in which Trump made the obstruction case against himself significantly stronger, a claim nobody really believed.

But as the kids on the internet say:

It's not just scandals, sexual or otherwise, in which the GOP has apparently decided it can say literally anything. Their entire party has decided that their tax plan, which showers benefits on the wealthy and corporations, will generate so much economic activity that it will pay for itself, despite the fact that this has never happened and will never happen, and not even conservative economists will claim it to be true. But it's what every Republican in Congress is saying, apparently on the theory that Paul Ryan is in possession of a pocketful of magic beans that will make it come true. That includes the supposedly moderate and thoughtful Sen. Susan Collins, who went on TV and cited conservative economists to support this fantastical claim; when The Washington Post's Jennifer Rubin contacted those economists, they said Collins doesn't know what she's talking about. And she's just about the sanest person they've got.

What unites these episodes is the belief that it really doesn't matter what you say when you're arguing for a candidate, a policy, or even a legal defense. There's no point in even trying to make your argument persuasive, because persuading people who might not already be with you isn't really the point. All you have to is signal to your partisans: This is what we're saying now, and yes I know it's ridiculous, but just say it.

And they will. To return to our friend Billy Bush and his supporting role in that historic episode, you may remember that after the Access Hollywood tape emerged, many Republicans panicked, assuming that Trump couldn't possibly win after he was revealed on tape bragging about his ability to sexually assault women with impunity. But they were wrong, and they've learned their lesson.

"People will just believe you. You just tell them and they believe you."