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.

The Bush tax cuts should be extended permanently for families with annual incomes of less than $250,000 and should be phased out slowly for those making more than that. Raising taxes on anyone now, when the economic recovery is so fragile, would be a mistake.

Past experience with fiscal austerity at home and overseas strongly suggests that it is best for the economy's long-run performance to restrain government spending rather than raise taxes.

There are different flavors of recession. You can get into some pretty dark scenarios pretty quickly.

Lenders look at potential borrowers from many angles before extending credit: How much of its income will a household need to put into debt repayment? How large is the down payment? Does the borrower have a job with a stable income? What is the borrower's credit score?

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.

There is a banking adage that if it's growing like a weed, it's a good chance that it's a weed.