NEGOTIATING WITH THOSE WHO OPPOSE THEIR OWN PRINCIPLES…. This week, a couple of key Senate Republicans said they would never agree to any compromise on energy policy if it included a cap-and-trade provision. If a proposal puts a cap on carbon emissions, and applies that cap to anyone or anything, anywhere, even a little, Republicans said they will kill the legislation and not allow the Senate to vote on it.

It led Mark Kleiman to raise a good point, and I hope he won’t mind if I quote it at length.

Why, I’m so old that I remember when market-simulating pollution-control regulations — polluter charges or cap-and-trade — were the official conservative alternative to command-and-control regulation. I was sympathetic to that critique, and frustrated about the environmental movement’s unwillingness to see reason. But now that the enviros have embraced a GHG tax or its cap-and-trade equivalent as the way to deal with global warming, conservative support is nowhere in sight. They’re all too afraid of Grover Norquist. Remember this the next time a conservative explains how we ought to voucherize public education. The minute that happens, the conservatives will come back and decide that we need to means-test the vouchers. That done, they’ll attack the remaining program as “welfare.” This is not a group of people it’s possible to do business with.

This is important. Cap-and-trade — any version of it — has been deemed wholly unacceptable by Republicans this year. But given the intense opposition to the idea, it’s easy to forget that Republicans used to consider cap-and-trade a reasonable, market-based mechanism that was far preferable to command-and-control directives that the right found offensive.

And I’m not talking about the distant past — the official position of the McCain/Palin Republican presidential ticket, not even two years ago, was to support cap-and-trade. Not just in theory, either. The official campaign website in 2008 told Americans that John McCain and Sarah Palin “will establish … a cap-and-trade system that would reduce greenhouse gas emissions.” McCain/Palin’s official position added, “A cap-and-trade system harnesses human ingenuity in the pursuit of alternatives to carbon-based fuels.”

Even George W. Bush awkwardly endorsed cap-and-trade before leaving office.

Democratic policymakers could, today, endorse the policy put forward by the Republican ticket from 2008, and GOP senators would filibuster it. Republicans said they wanted cap-and-trade, but now refuse to take “yes” for an answer.

The goal posts are always on the move, which in turn makes substantive policymaking with Republican lawmakers practically impossible.

Indeed, after Kleiman posted his piece this week, plenty of others noticed how common the phenomenon is. Matt Yglesias noted:

Another major example I can think of is the Earned Income Tax Credit, once touted as the conservative alternative to welfare and/or restoring the real value of the minimum wage, but now supported almost exclusively by liberals while conservatives castigate the poor for not paying taxes. Section 8 housing vouchers, put forward as an alternative to public housing and then repeatedly cut by GOP congresses is another one. Of course this kind of consideration doesn’t invalidate any given idea — I think auctioned, tradable emissions permits actually are the best way to regulate most sources of pollution and that housing vouchers are superior to old-school public housing. But this kind of continual pulling away of the football by the conservative movement makes it quite difficult for us to reach stable consensus around decent policies.

Ezra Klein noted that Republicans used to support industry bailouts, but now consider them creeping socialism. Jon Chait noted that the Republicans “fervently embraced the logic of Keynesian stimulus in 2001,” but now fundamentally reject the same idea.

In perhaps my favorite example, the concept of an individual mandate as part of health care reform was, in fact, a Republican idea. Now, the GOP considers it the single most offensive part of the Democratic policy.

The point isn’t to point out Republican inconsistencies; that’s fairly routine. The point is to demonstrate that Republicans are so fundamentally unserious about solving public policy challenges, that they’ll shamelessly move the goalposts at a moment’s notice. The party supports cap-and-trade, EITC, industry bailouts, housing vouchers, and mandatory health insurance — right up until there’s a Democratic president. Then, Republicans are no longer willing to even consider Republican ideas.

When the David Broders of the world lecture the dysfunctional Congress on the importance of policymakers working together in good faith, this dynamic tends to be overlooked entirely. Credible people who are serious about solving problems can formulate consensus solutions. But they’ll invariably fail because Republicans have no qualms about fighting against their own proposals.