When I see Delong more or less indiscriminately trashing everyone at Chicago, or Krugman trashing Barro, etc., what doesn’t arise in my mind is a sense that some of these guys really know what they’re talking about while some of them are idiots. What arises in my mind is the strong suspicion that economic theory, as it is practiced and taught at the world’s leading institutions, is so far from consensus on certain fundamental questions that it is basically useless for adjudicating many profoundly important debates about economic policy. One implication of this is that it is wrong to extend to economists who advise policymakers, or become policymakes themselves, the respect we rightly extend to the practitioners of mature sciences. There is a reason extremely smart economists are out there playing reputation games instead of trying to settle the matter by doing better science. The reason is that, on the questions that are provoking intramural trashtalk, there is no science.
I'd hypothesize that the reason for this is that economics is not merely not a science, but that any given school of economic thought or tradition of inquiry and research merely reifies the circumstances and conditions of a previous era, policy framework, or set of conundrums, whereas all of these things are much more circumscribed, historically speaking: things work, or don't, until they don't, or do, and the permutation space of possible Lessons of Economic History is rather smaller than anyone wishes to believe.
(HT: Jim Manzi.)