“I continue to stick to my guns that we’re not going to fall backward into a recession,” said David Crowe, the chief economist at the National Association of Home Builders. “It’s just hard to figure out how you can get much lower than we are already.”

It is the simple math of recession. Consider housing, which is typically a major factor in recessions. At the peak of the last boom, Americans were spending $813 billion a year on residential investment. That figure bottomed out last year at only a $327 billion.

In other words, a major part of the story of the economic downturn was of half a trillion dollars in spending on new houses and apartment buildings vanishing from the economy.

Since hitting its low ebb, residential investment spending has rebounded only slightly, to a $336 billion annual rate this past spring. That means that, mathematically, it would be impossible for a new housing downturn to be as powerful an economic drain now as it was over the past several years; there isn’t $500 billion worth of housing activity left to vanish. Even if housing investment fell back to its low point from last year, that would subtract a trivial $9 billion in economic activity from overall growth.