Paul Krugman. His answer to Queen Elizabeth II’s now-famous question: “Why did no one see it coming?”
Krugman’s cheerful response is that the New Keynesians were looking the other way. Theirs was a failure not of theory, but of “data collection.” They had “overlooked” crucial institutional changes in the financial system.
While this was regrettable, it raised no “deep conceptual issue” – that is, it didn’t demand that they reconsider their theory.