Going to the well again

It's too good. The Barro piece in the WSJ was an embarrassment, Krugman calls him on it.

[W]hy, exactly, are we supposed to have such faith in “regular economics”? What is the compelling evidence that the vision of a competitive, efficient economy allocating resources to the right uses is actually a good description of the world we live in?

I mean, it’s a lovely model, and one I, like everyone else in economics, use a lot. But I would not have said that it’s a model backed by lots of evidence. We do know that demand curves generally slope down; it’s a lot harder to give good examples of supply curves that slope up (as a textbook author, believe me, I’ve looked); and it’s a very long way from there to the vision of Pareto efficiency and all that which Barro wants us to take as the true economics. Realistically, imperfect competition, market failure, and more are everywhere.

To which I can only add this.