Reality TV star and presumptive Republican presidential nominee Donald Trump  has convinced thousands of people that he s an expert on business, finance, and commerce. There isn t much evidence of those claims, and as he consolidates his power at the head of the Republican Party, his words reveal a dangerous lack of knowledge about global economics.In an interview with CNBC (on the phone, of course) Trump proposed a radical idea. He told the interviewer that he would reduce the national debt by having the United States fail to pay back on the money it owes. I would borrow, knowing that if the economy crashed, you could make a deal,  he told CNBC.  And if the economy was good, it was good. So, therefore, you can t lose. Trump doesn t seem to understand that the United States economy isn t one of his many, many casinos and other ventures that he sent into bankruptcy at the expense of his investors (and rarely himself). To set him straight, Gene Sperling, who was an economic adviser to Presidents Clinton and Obama, released a statement lacerating Trump s insane proposal: For Donald Trump to casually announce he would consider defaulting on our debt for the first time in our history shows a stunning lack of responsibility and understanding of the global economy,  he said.Sperling also pointed out that Trump s plan  would risk a global financial meltdown, drive up interest rates for Americans for decades, and seriously harm middle-class families. In case anyone might think that this is simply a case of a Democrat hitting Trump, Republicans and business experts also think his idea is bonkers:Tony Fratto, a spokesman for the U.S. Treasury Department under former President George W. Bush and a vocal member of the  Never Trump  movement, called the comments  dumb as a bucket of rocks.  Fortune Editor Alan S. Murray called them  scary. In Trump s first week as the Republican standard-bearer, he s revealing just how ill-prepared he is to govern, more than even your average modern Republican.Featured image via Flickr