A lot of news coverage this past week has taken note of Trump's policy reversals, several of which Trump himself has attributed to learning things he didn't know.
For example, during the campaign he declared that it would be easy to solve the U.S. health insurance problem to enable everyone to get high quality care at low cost, but when the House Republicans lacked the votes to pass Paul Ryan's plan -- which would actually have cost millions of people their insurance -- Trump told a meeting of American governors, "Nobody knew health care could be so complicated."
More recently, Trump thought China could deal with North Korea's nuclear threat, but as Trump told The Wall Street Journal, when he raised the subject with Chinese President Xi Jinping, Xi gave him an impromptu history of Chinese-Korean relations that changed his mind. "After listening for 10 minutes, I realized it's not so easy," Trump said.
He's also decided that China isn't a currency manipulator after all, that NATO is "no longer obsolete" (inaccurately suggesting that this was based on changes at NATO), and so on.
All presidents learn on the job, but they usually start a lot farther ahead, and they usually surround themselves with experienced people. Trump is the only president in American history with no prior experience in government, and while some of his cabinet nominees and White House advisors have been decent if not ideal choices, too many are hopeless unqualified or outright cranks, and Trump is well behind naming people to fill a large number of jobs.
(For comparison, Obama, caricatured by Republicans as inexperienced, served three notably productive terms as an Illinois state senator before being elected to the U.S. Senate, and in both cases worked with both Democrats and Republicans to introduce and pass laws. Prior to that he'd been among other things a professor of constitutional law. As president he hired and listened to qualified and experienced people and he filled posts at a much higher rate than Trump, or George W. Bush for that matter.)
Maybe Trump really can learn on the job, though it's a little troubling to think of him leaning on the president of China for advice rather than American experts, or apparently basing a lot of his thinking on the last thing he saw on Fox News.
(Updated 2017 April 17 with some minor edits.)