What did Donald Trump do today?

He exaggerated the growth in the United States' GDP on his watch by a factor of about 43.

Trump gave an interview with the British tabloid The Sun today. It's already attracting attention for the fact that he used it to open try to destabilize the coalition government led by Prime Minister Theresa May, among other incendiary comments. 

But it also contained a lie about the American economy that was remarkable even by Trump standards: that the United States' GDP--that is, the total value of goods and services produced in the country--had "doubled and tripled" since he took office. (That statement is at 3:30 in the first audio clip at this link.)

Doubling GDP would mean a 100% growth rate. Last year, the U.S. economy grew by about 2.3%. The annualized rate was 2.2% in the first quarter of 2018. 

It's possible Trump simply became confused about what GDP meant or what economic growth was. (In fact, given his problems with basic economic concepts, it's possible he never knew.) But because interviews are unscripted, Trump also has a habit of straying into bizarre, impossible, or even self-incriminating territory during them--which is why his aides try to prevent them as much as possible. 

So what?

• A president who isn't in control of himself, or in touch with reality, can't do the job.

• Past a certain point, it doesn't really matter whether someone is lying or incompetent.