Defaulting on the nation's debt would be cataclysmic. The U.S. Treasury's Aaa rating is the one constant in the world's financial system. When times are bad anywhere on the planet, global investors flock to Treasury bonds because they know they will get their money back.

Indeed, the FHA was born out of the Great Depression, which was also caused in significant part by a foreclosure crisis. Mortgages in the early 1930s were mostly three- to five-year 'bullet' loans, which did not amortize and were due in full at maturity.

Predicting recessions is indeed a dark art, but I think we are several years away from the next one.

The upshot of Mr. Trump's economic policy positions under almost any scenario is that the U.S. economy will be more isolated and diminished.

There is plenty of blame to go around for the U.S. housing bubble, but not much of it belongs to Fannie Mae and Freddie Mac. The two giant housing-finance institutions made many mistakes over the decades, some of them real whoppers, but causing house prices to soar and then crater during the past decade weren't among them.

Too-easy credit and millions of bad loans made during the U.S. housing bubble paved the way for the financial calamity and Great Recession that followed. Today, by contrast, credit is too tight. Mortgage loans are particularly hard to get, creating a problem for the housing market and the broader economy.

Defaulting on the nation's debt would be cataclysmic. The U.S. Treasury's Aaa rating is the one constant in the world's financial system. When times are bad anywhere on the planet, global investors flock to Treasury bonds because they know they will get their money back.