But there’s a sense in which the pipeline protesters and Midwestern unions are exactly the people that the O.W.S. crowd should not learn from, if they aspire to appeal to a wider audience than left-wing activists usually reach.

Yes, Occupy Wall Street was dreamed up in part by flakes and populated in part by fantasists. But to the extent that the movement briefly captured the public’s imagination, it was because it seemed to be doing what a decent left would exist to do: criticizing entrenched power, championing the common good and speaking for the many rather than the few.

The union rallies and the Keystone demonstrations, by contrast, represented what you might call the decadent left, which fights for narrow interest groups rather than for the public as a whole.

The Wisconsin protests didn’t defend American workers’ right to bargain for their fair share of company profits, as traditional union protests have. They defended government employees’ right to negotiate with elected officials over the division of taxpayer dollars — a recipe for profligacy that even liberal icons like Franklin Roosevelt and the A.F.L.-C.I.O.’s George Meany once opposed.