information:filtering, linguistic:paraphrasing
NAIRU and rational expectations

The rational expectations theory said that expectations of inflation were equal to what actually happened, with some minor and temporary errors. This, in turn, suggested that the short-run period was so short that it was non-existent: any effort to reduce unemployment below the NAIRU, for example, would immediately cause inflationary expectations to rise and thus imply that the policy would fail. Unemployment would never deviate from the NAIRU except due to random and transitory mistakes in developing expectations about future inflation rates. In this perspective, any deviation of the actual unemployment rate from the NAIRU was an illusion.