Krugman has been refuted (2014). Keynes and the Post Keynesians have been refuted (2011). Traditional Heterodoxy has failed to replace these degenerate research programs by a progressive program. Economists have a realistic self-perception and know well that they will never get out from under the self-produced heap of scientific rubbish: “Yet most economists neither seek alternative theories nor believe that they can be found.” (Hausman, 1992, p. 248). The Malmö branch of Heterodoxy has even fallen into total apathy and reduced itself to the endless repetition of: ‘We know that we know nothing.’
Whether Krugman is entitled to call himself a New Keynesian is a matter of indifference outside the economics kindergarten. Krugman has nothing to offer in the way of scientific insights about how the actual economy works. He is a political economists and political economics has not produced anything of scientific value in the last 200 years.
Walrasianism, Keynesianism, Marxianism, Austrianism are materially/formally inconsistent, that is, provable false. The problem is that all four approaches are tied to political groups/interests and are used as a means of persuasion/propaganda/justification. The current versions of economics have no scientific raison d’être, merely some political utility.
When Krugman supports the Democrats, when Wren-Lewis and Keen support Corbyn, when Varoufakis fights for democratizing the Eurozone, has this anything to do with science? What have they and Hayek and Keynes and Friedman in common? NEITHER of these so-called economists has a scientifically valid theory about how the economy works.
Political economists have made economics a banana science. Krugman is a prominent representative of this aberration. From the position of constructive Heterodoxy, Krugman is out of science and his contributions to economics are sitcom stuff.* Science and politics do not mix, never have, and never will. Political economics is NOT economics.
Hausman, D. M. (1992). The Inexact and Separate Science of Economics. Cambridge: Cambridge University Press.
Kakarot-Handtke, E. (2011). Why Post Keynesianism is Not Yet a Science. SSRN Working Paper Series, 1966438: 1–20. URL
Kakarot-Handtke, E. (2014). Mr. Keynes, Prof. Krugman, IS-LM, and the End of Economics as We Know It. SSRN Working Paper Series, 2392856: 1–19. URL
* For a map of current/future economics see on Wikimedia
For more details of the big picture see cross-references Political economics and Incompetence
For the after-election sequel see on Zero Hedge
You overlooked what Napoleon has said about economists: “Late in life, moreover, he claimed that he had always believed that if an empire were made of granite the ideas of economists, if listened to, would suffice to reduce it to dust.” (Viner, 1963)
Economists in their abysmal incompetence were a public danger then and in the interim things have worsened. You say “Truth, untruth, who knows and cares.” This has always been the motto of political economists.
Newton stood on the shoulders of scientific giants, economists stand since Adam Smith on the shoulders of political cockroaches.* It suffices to look at who has achieved what in the last 200 years.
* See cross-references Incompetence