Krugman commits an intrinsic contradiction; and if that's too strong of an interpretation, then we should at least call it an unresolved tension. There's Exhibit A:
[I]nfluential people on both sides of the Atlantic heaped praise on the prophets of austerity ... because the doctrine of expansionary austerity dovetailed with their ideological agendas.
Versus Exhibit B:
[P]olicy makers, pundits and, I’m sorry to say, many economists decided, largely for political reasons, to forget what they used to know.
Krugman is not alone in blurring these vitally distinct propositions: Conservative (I would say "pseudoconservative"), anti-Keynesian Western pols are genuinely entrenched in "their ideological agendas," yet they simultaneously, and with aforethought, have deployed these agendas "largely for political reasons"? Either the former negates the latter, or the latter -- as the term "for political reasons" is generally understood -- obliterates the former. Which is to say, either these pols sincerely believe in their agendas, or they are merely opportunistic, pandering windbags.
I mentioned that Krugman isn't alone in this blurring, since I've committed the selfsame ambiguity countless times. So this isn't a criticism of Krugman, but an honest puzzlement. Are these anti-Keynesian pols of "expansionary austerity" really that ideologically dimwitted? -- as Krugman notes, "any economist ... or for that matter any undergraduate who had read Paul Samuelson’s textbook 'Economics' ... could have told you that austerity in the face of depression was a very bad idea" -- or are they just playing to the dimwitted crowd, understanding, as they do, that the simplicity of Cut spending! is, compared to perhaps complicated macroeconomics, a stirring comprehensibility.
I don't know. It's unanswerable -- or at least with any real and final authority, it's unanswerable. My native cynicism, however, compels the suspicion that, say, John Boehner and Mitch McConnell, or Mitt Romney and Newt Gingrich, aren't really so dumb as to believe that slashing federal spending while in the powerful gusts of economic headwinds is a smart idea. Even the most rudimentary of empirical economics belies such an opinion. Still, such an opinion can be a humdinger of a crowd-pleaser, assuming the crowd itself has for years meticulously evaded all enlightenment while languishing in its Platonic cave -- e.g., has been boobtube-glued to nothing but Fox News' glittering disinformation.
Such a suspicion suggests nothing less than the politically sociopathic on the part of Messrs. Boehner et al. My apologies if that's rhetorically strident -- but maybe, just maybe, profoundly true.