When the president of the United States makes several major shifts on policy in the course of the week, it’s bound to raise a series of questions. Luckily, there’s someone whose job is to answer those questions, giving the press information about the president’s thinking and direction: the White House press secretary.

At least in theory. Sean Spicer seemed less than enthused on Thursday about trying to explain why Donald Trump shifted his view on issues ranging from the Export-Import Bank to interest rates to Chinese currency manipulation in an interview with The Wall Street Journal. Trump also announced that NATO, which he had said was obsolete, is no longer obsolete. During Thursday’s White House briefing, reporters wanted to know what had happened, and what this meant for other Trump positions—were they equally malleable?

Spicer gamely began with a physics- and grammar-bending metaphor.

“I think, respectfully, I think you can look at what you’re referring to as a shift in a lot of ways, and by that I mean I saw a couple instances with respect to NATO being one of those shifts, and if you look at what’s happened, it’s those entities or individuals in some cases or issues evolving toward the president’s position,” he said.

On NATO, Spicer noted that Trump had demanded that the alliance focus more on terror and that other members increase their defense spending. Both those things are seeing movement, Spicer said. This is fair as far as it goes: The changes may not be due to Trump, but there has been movement.

But it doesn’t explain the economic-policy shifts, and on those Spicer was rather more vague. Why had the president decided the Ex-Im Bank wasn’t such a bad idea?

“Let me get back to you on the Ex-Im bank. It’s a very complex issue and I would like to get back.”

Why does Trump no longer believe China is devaluing its currency, even though he has said so as recently as February?

“It’s a very, very complex issue and I’m gonna leave it to the president to specifically answer it,” Spicer offered.

There’s an element of comedy to this: Spicer’s job is to explain the president’s positions to the press and the public. And sure, the press secretary can’t be expected to be an expert in every topic. Except that Spicer knows a thing or two about trade policy, having served as a spokesman for the Office of the U.S. Trade Representative during the George W. Bush administration.

Spicer’s had a rough week. On Tuesday, he stumbled into an unfortunate and ill-conceived comparison between Bashar al-Assad and Adolf Hitler, only digging himself deeper before realizing his error and trying to reverse it. It’s also hard to defend Trump when he changes his positions so abruptly, especially while admitting in some cases that he simply did not understand the question at hand. Moreover, Spicer has reason to be nervous. Trump is believed to watch press briefings closely. Spicer could be concerned about wedding himself too closely to any one position, since Trump could easily just change his mind back. He has on occasion contradicted Spicer’s statements in the briefing room.

Still, the correct answer is surely to defend whatever whatever the president says his policy is right now. If even his own spokesman can’t understand and explain that, how is anyone else to do so?