For the most part, U.S. presidential campaigns are long slogs punctuated by short gaffes. Think of Rick Perry’s “oops,” Mitt Romney’s “47 percent” or Howard Dean’s scream. Like the MVP who misses the game-deciding foul shot in the championship, one mistake can erase a season of disciplined campaigning in an instant.

Then there’s Donald Trump. These rules of political gravity do not apply to him. From insulting Sen. John McCain for getting captured in Vietnam to flubbing Jake Tapper’s question about the Ku Klux Klan, Trump’s 2016 campaign has been an extended gaffe.

At Thursday night’s Republican debate, Trump gave us plenty of head-scratchers. He said for example that the wives of 9/11 hijackers were whisked out of the country before 9/11. This was in response to a question about his earlier remark that he would not only go after terrorists as commander-in-chief, but that he would also target their families.

Then there was Trump University. In an exchange with Marco Rubio (whom he kept calling “little Marco”), Trump said the students of his for-profit college gave it high marks and then said he had reimbursed many of the students who asked for their money back.

So far these kinds of gaffes have had no effect. Indeed, it is part of Trump’s appeal. He tells it like it is. He’s not afraid to say things that are politically incorrect. Unlike career politicians, Trump is unscripted. Sure, the Beltway mandarins are sickened at the thought of deporting millions of illegal immigrants, but this is exactly the kind of policy the Republican base desires. The fact that elites are shocked is a feature, not a bug. As Michael Kinsley famously observed, a gaffe in Washington is when a politician accidentally tells the truth.

But this game works only if we assume Trump means the shocking things he has been saying. There’s a good chance he doesn’t.

This was a theme in Thursday’s debate. Sen. Ted Cruz for example attacked Trump three times for writing checks to Hillary Clinton’s 2008 presidential campaign. He asked how someone who claims to be so tough on immigration could support someone who was on the other side of this issue.

In his own way, Rubio too made this point about Trump. Rubio reiterated his line that Trump is a con man, willing to scam the suckers who enrolled in his for-profit university the same way he is scamming Republican primary voters.

It was the Fox News moderators however who really drove this point home. First they asked him about an off-the-record interview he gave to the New York Times. Buzzfeed reported this week that Trump in January told the paper that his positions on immigration were flexible. This led to a bizarre answer from Trump in which he claimed he would not authorize release of the tape of this interview because he sought to honor the off-the-record agreement he made with the Times.

Then the moderators played clips of Trump contradicting himself in television interviews on whether he supported the Afghanistan war and allowing Syrian refugees into the U.S. Trump’s response was not very Trumpian. He tried to explain that he may have said different things to different people, but that was only because he had meant to be consistent. At other times in the debate, Trump tried to make a virtue of his flexibility, explaining that this was what was needed to be effective in Washington.

Trump has said this kind of thing before. He is after all a great deal maker, he assures us.

But on Thursday night, it sounded different. When questioned about his contradictions, the unscripted outsider dissembled. Trump sounded evasive and uncertain. He sounded like a politician, for whom the rules of political gravity may still apply.

(c) 2016, Bloomberg View · Eli Lake  / Bloomberg photo by Andrew Harrer)