that the Phillips curve was only applicable in the short run and that, in the long run, inflationary policies would not decrease unemployment. Friedman correctly predicted the stagflation of the 1970s.

In the 2010s the slope of the Phillips curve appears to have declined and there has been controversy over the usefulness of the Phillips curve in predicting inflation. A 2022 study found that the slope of the Phillips curve is small and was small even during the early 1980s. Nonetheless, the Phillips