The problem with Donald Trump isn’t just that he lies constantly, but also that he can’t keep his story straight. On Sunday, he issued forth a string of tweets about the election results and the ongoing recount efforts launched by Green Party leader Jill Stein. They advanced three separate arguments. The first tweet read: “So much time and money will be spent [on the recount]—same result! Sad.” The subsequent tweet read: “In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally.” And the next two tweets formed a single thought: “It would have been much easier for me to win the so-called popular vote than the Electoral College in that I would only campaign in 3 or 4-states instead of the 15 states that I visited. I would have won even more easily and convincingly (but smaller states are forgotten)!”

What’s interesting about these three tweets is that, on the face of it, Trump’s second point contradicts both his first and third assertions. For if Trump truly did win the popular vote despite massive fraud (as alleged in point 2), then a recount wouldn’t give the same result, as he’s asserting in the first tweet. And saying that Trump is already the real popular-vote winner flatly goes against saying he would have been the popular-vote winner if that had been his goal. It’s logically possible that points 1 and 3 are right, or that point 2 is right. It’s impossible that all three are right.

Fact-checkers have done a fine job of debunking Trump’s wild assertion that millions voted illegally, although many headlines too credulously described it simply as a “claim” rather than a demonstrable falsehood. But the media response to Trump’s dishonesty shows the limits of fact-checking. Fact-checkers typically look at individual comments a politician makes and judge them against known evidence. That’s fine so far as it goes, but it simply establishes the accuracy or inaccuracy of that one statement, rather than the pattern of deception or even irrationality at work.

Trump is out to create a post-truth world where his assertion of the moment is the only thing that counts.

At the end of a wholly persuasive refutation of Trump’s claim about actually winning the popular vote, for instance, Glenn Kessler at The Washington Post offered this meta-analysis: “Now that Trump is on the verge of becoming president, he needs to be more careful about making wild allegations with little basis in fact, especially if the claim emerged from a handful of tweets and conspiracy-minded websites. He will quickly find that such statements will undermine his authority on other matters.”

This analysis assumes that Trump wants to govern like a normal president, so that if he’s caught in untruths, he’ll face a credibility gap like the one that plagued Lyndon Johnson. What it fails to entertain is the possibility that Trump’s lies aren’t just incidental to his approach to politics but essential to it, that the president-elect sees lying as the source of his authority rather than as something that undermines it.