Democrats are bringing back earmarks, and plenty of media voices are cheering the development. Some commentators, on both the Left and the Right, say earmarks are the grease that makes the congressional machine work. Another defense, from some conservatives and libertarians, is that Congress rightly should exercise more spending authority than it does and should cede less to the executive.

Both of these arguments have merit and ought to be weighed against the costs (in terms of corruption, mostly, of earmarking). But one argument that strikes me as naive is that earmarks are just about helping out local communities. I believe this ignores both the economics and the politics of earmarks.