Several prominent bloggers are arguing that the commercial real-estate downturn is undermining theories that the government or predatory lenders led to the housing bubble, which could change how regulatory reform is shaped. Here's what's being said:

• The Damning (Dis-)Proof  Last night, Paul Krugman posted what he called a "highly significant" graph that he and other -- mostly left-of-center -- bloggers say is pretty clear proof that the bubble was neither the fault of government programs nor predatory lenders. The graph shows two similarly skewed bell curves -- one each for the residential and commercial real estate markets. The conclusion everyone is drawing is that if a) predatory lending and government programs were aimed only at the poor, which they were, and b) there was a matching commercial and residential boom and bust, as shown in the graph Krugman posted, then c) neither government programs nor predatory lending can fully be the cause for the bubble.

• You've Got It Backwards  Mother Jones' Kevin Drum and Think Progress' Matthew Yglesias both think that Krugman's graph may show that the bubble caused predatory lending and poor government policies, not the other way around. "The bubble provided more opportunity for predatory lending," Drum writes. Yglesias adds that "Fannie & Freddie didn't create the housing bubble, the money that non-GSEs were making off the bubble housing bubble pushed Fannie & Freddie into unsound behavior."

• It's Stupidity, Stupid  So what are bloggers saying did cause the bubble? "In both cases, prices were propped up by vastly increased use of debt and leverage at all levels," Drum writes. The Atlantic's Megan McArdle puts it more simply: "Though the commercial real estate bubble was smaller in scope than the residential one, it was characterized by essentially the same pathologies: rising prices, stupid banks, and stupid borrowers."

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