At least in theory, Mitt Romney and Michele Bachmann represent very different elements of the Republican Party. When the former is echoing the strange arguments of the latter, there’s a problem.

In last night’s debate, for example, Romney complained that gasoline prices have “doubled” since President Obama took office. If this line sounds familiar, it’s because Bachmann repeated it in nearly every stump speech for months.

The argument also happens to be ridiculous.

More important, though, is the reason that gas was — comparatively speaking — so cheap a few years ago. It wasn’t because the U.S. was suddenly pumping more oil, or because the Saudis had decided to flood the market, or because the head of ExxonMobil lost his mind and started to give all Americans a 2-for-1 deal on gas. The U.S. — and the world — was in the depths of the worst recession since the 1930s, depressing demand for everything from data centers to electricity to driving.

It’s Econ 101: precipitous falls in demand usually trigger precipitous falls in price, which is what happened to gas prices, dropping from a high of $4.05 a gallon in mid-July 2008 to a low of $1.69 a gallon at the end of December that year.

As Romney has noted repeatedly, under Obama, the economy has “gotten better.” And as the economy improved, demand went up, and the price of gas started climbing. This really isn’t complicated.

And yet, despite the simplicity of reality, Romney is spewing nonsense. Indeed, I’m not sure which is worse — the idea that Romney believes Bachmann’s silly talking points have merit, or the idea that Romney understands the facts just fine and wants to deceive the public on purpose.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.