Economics outside the academy has become the continuation of politics by other means. If you wish to know what Mr [Paul] Krugman thinks on any policy question, do not read his scholarly writings; see which policies are advocated by the progressive wing of the Democratic party. Mr Krugman agrees with liberal Democrats about most things, and for the rest gives as much cover as the discipline of economics can provide - which, given its scientific limitations, is plenty. He does this even on matters where, if his scholarly work is any guide, the economics is firmly against his allies. Liberal Democrats are protectionists. Mr Krugman is not, but politics comes first.
The syndrome affects economists on the right as much as on the left. Just as there is a consensus among economists that protectionism should be opposed, most economists believe that a powerful fiscal stimulus is both possible and desirable in present circumstances, and that the best stimulus would include big increases in public spending. Yet recently, Robert Barro, a scholar with conservative sympathies, wrote in the Wall Street Journal that this view was an appeal to "magic".
The problem is not that Mr Krugman questions the consensus on trade (if indeed he does), or that Mr Barro questions the consensus on fiscal policy (as he certainly does). It is that both set the consensus aside so carelessly. In doing so, these stars of the profession destroy the credibility of their own discipline. Mr Krugman gives liberals the economics they want. Mr Barro gives conservatives the same service. They narrow or deny the common ground. Why does this matter? Because the views of readers inclined to one side or the other are further polarised; and in the middle, those of no decided allegiance conclude that economics is bunk.
Crook threw in a (mostly accurate) criticism of the blogosphere as well:
The web, for all its blessings, is an aggravating factor. Many of the most successful economics blogs promote communication within political groupings, not across them. On the web you best build an audience by organising a claque and stroking its prejudices. Extend elaborate courtesy to people you agree with and boorish contempt to those who do not get it. Celebrate exasperation and incivility as marks of intellectual authenticity - an attitude easier to tolerate in teenagers under hormonal stress than in professors at world-class universities.
For Krugman's and Barro's respective responses to that column, see Crook's Atlantic blog post, "The Dismal Science, Revisited".