ANOTHER MONTH, ANOTHER EXCUSE…. That Joe Lieberman would rather kill health care reform than let some consumer choose between competing public and private plans isn’t exactly new. I continue to find it fascinating, though, to see his evolving explanations.

In June, Lieberman said, “I don’t favor a public option because I think there’s plenty of competition in the private insurance market.” That didn’t make sense, and it was quickly dropped from his talking points.

In July, Lieberman said he opposes a public option because “the public is going to end up paying for it.” No one could figure out exactly what that meant, and the senator moved onto other arguments.

In August, he said we’d have to wait “until the economy’s out of recession,” which is incoherent, since a public option, even if passed this year, still wouldn’t kick in for quite a while.

In September, Lieberman said he opposes a public option because “the public doesn’t support it.” A wide variety of credible polling proved otherwise.

In October, Lieberman said the public option would mean “trouble … for the national debt,” by creating “a whole new government entitlement program.” Soon after, Jon Chait explained that this “literally makes no sense whatsoever.”

Well, it’s November. And guess what? We’re onto the sixth rationale in six months. I actually like the new one.

“This is a radical departure from the way we’ve responded to the market in America in the past,” Lieberman said Sunday on NBC’s “Meet The Press.” “We rely first on competition in our market economy. When the competition fails then what do we do? We regulate or we litigate…. We have never before said, in a given business, we don’t trust the companies in it, so we’re going to have the government go into that business..”

What a pleasant change of pace. Lieberman is moving away from practical and policy arguments — that’s a good move, since he’s totally wrong on the merits — and shifting towards opposition based on traditions.

That’s at least creative. We haven’t set up public plans to compete with dysfunctional private models before, therefore we shouldn’t in the future. The first half of the equation may very well be true, but the second half is more of an observation than an argument.

In a nutshell, reform advocates are saying, “Giving people the choice of a public option is likely to help consumers by cutting costs and promoting competition.” Lieberman is effectively responding, “We haven’t done things that way in the past.”

To which I respond, “So?”

The goal here is not to preserve ideologically-based traditions; the goal is to help consumers get the care they need at a price they can afford.

But don’t worry, December is almost here. Lieberman will have a new line soon enough.

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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.