Matt Yglesias, Kevin Drum, Jon Bernstein and a few others have raised, I think, the strongest counterargument to my column arguing that policies that are considered liberal today are policies that Republicans thought up and supported through the ’90s and, in some cases, the mid-Aughts. The argument, in short, is that Republicans may have conceived of these policies, but they never really supported them. They were developed tactically in order to head off Democratic policies Republicans liked less. As Drum says, “it’s only natural that they haven’t supported any of these things under the Obama administration. They never really did, after all, and this time around they felt that flat-out opposition was politically feasible.”

I think the correct answer to this is: so what? Or perhaps: that’s the point.

I don’t think it’s possible to really “know” if Republicans ever supported, say, cap-and-trade. Tim Pawlenty certainly seems to have supported it. Back when he was governor of Minnesota, he cut commercials in favor of cap-and-trade and signed bill setting strict limits of carbon emissions. But maybe he was just playing 12-dimensional chess against a carbon tax or something. In the end, I don’t really care.

There was a time when these policies were supported by conservatives as a market-oriented alternative to liberal ideas. That much is easy to document. Now they’re associated with liberals. That’s important context for our current debate. American politics is an ongoing fight between Democrats and Republicans, and we largely take the two parties at their word that the fight is essentially about what they say it’s about. But if you look at the left/right divide through policy rather than party, it looks very different: the right of 10 and 20 years ago would be considered the left of today, even though, in many cases, we’re talking about the same people. The same policies which were, a decade ago, the alternative to command-and-control economics and government-takeovers of the health-care system are, today, the epitome of command-and-control economics and government-takeovers of the health-care system.

The takeaway here isn’t “BREAKING: Politicians can be cynical!” Cynicism is an overrated explanation for how people act. My hunch is that Republicans and Democrats mostly do support the policies they say they support, at least at the moment they say they support them, but people’s attachment to holding or regaining the majority tends to be much stronger than their attachment to specific policy plans, and so opinions align in whichever way is necessary to maximize the chances of political success in November. Many of these flip-flops are, for the most part, sincere. You don’t need to keep an especially skilled rhetoritician on retainer if all you’re doing is helping people believe what they want to believe. But much more commonly, these flip-flops are unnoticed. Most people do not pay in­cred­ibly close attention to policy, and so don’t realize how much or how fast the ground shifts in a decade.

But the fact remains: the ideological valence of policies isn’t, or shouldn’t be, considered identical to the ideologies of the parties that support them. The Republican Party might abandon cap-and-trade, but neither the media nor the public should forget that the Republican Party came up with cap-and-trade. Barack Obama might support cap-and-trade, but that doesn’t make cap-and-trade an exclusively liberal idea, even if its support, in the 2009-2011 period, mainly comes from liberals. It’s fair enough for the two parties to try and move the goalposts when their current positions cease to suit them. But that’s something that interpreters of politics should resist, and one way to resist it is to keep a close eye on policy. That partisanship explains political behavior far better than policy or philosophy is both something I’ve argued many times before and something that I think gets far too little attention. Hence the column.