I didn’t realize it, but just before my lament over the imperviousness of conventional wisdom to evidence, Simon Wren-Lewis made a similar point, but more broadly. Reading his post, I had some further thoughts.

To this day, one often hears pundits and establishment types in general talking as if we had a clear distinction between the elite, who know How Things Work, and the great unwashed who need to be led to elite wisdom. The reality, however, is nothing like this. It’s true that there are crank doctrines — goldbuggery, the Laffer curve,etc. — that play a substantial role in popular opinion but have no traction with the elite. But the elite itself has spent much of the past five years committed to economic doctrines — the prevalence of structural unemployment, the urgency of deficit reduction and entitlement reform, the destructive effects of “uncertainty” — that may not be quite as contrary to the evidence as fears of hyperinflation just around the corner, but are pretty bad. And the influence of these doctrines has remained almost unscathed even though this past year should have driven them completely out of respectable discussion.

It has, after all, been quite a year — not just the sea-change in professional opinion on structural unemployment, but the collapse of the expansionary austerity doctrine and its replacement by the view that multipliers are quite large, the collapse of the 90 percent debt threshold view, the plunging deficit and the vanishing of medium-term debt concerns, and more.

Yet policy hasn’t changed at all, and elite views have hardly shifted. How is this possible? Wren-Lewis hits the main points: politicians seek out economists who reinforce their prejudices; news media are either propaganda organs or desperately afraid of declaring, in any straightforward way, that politicians are wrong, no matter how much what they say is at odds with the truth.

That is, by the way, where the PolitiFact deficit bungle comes in. Eric Cantor says that the deficit is growing when it’s actually falling fast; PolitiFact rules this “half true” because projections suggest that the deficit will rise (modestly) after 2015. It’s as if I said it was raining when it was actually sunny, and you declared my statement half true because (unreliable) weather forecasts call for rain later in the week. The reality, surely, is that the so-called fact checkers thought they were playing it safe, avoiding calling a top GOP official either uninformed or a liar; as it turns out, they’re getting a different kind of grief, and that’s a good thing.

But back to the frustrations of policy analysis. Obviously economists have to do what they can to get things right, and get the word out. But the past five years have been a disappointing revelation: knowledge, it seems, isn’t power, and actual power is all too eager to ignore actual knowledge in favor of stuff that sounds Serious and/or serves an agenda.