What surprises me about the Phillips curve is that anyone ever took it seriously in the first place.(posted 8758 days ago)Back when inflation was "a problem," I used to study the various theories of the causes of inflation. In the case of all of them, I sooner of later found the point where the theory went " mumble, mumble, the money supply expands relative to the volume of goods and services produced." If the authors of the theories were pressed, they invariably explained that of course, if the money supply stayed stable, all kinds of terrible things would happen, but prices would remain stable. If they asked what would happen if the money supply was expanded without any of the things taking place that their theories used to explain inflation, they would claim it wouldn't happen, but eventually get around to admitting that prices would rise.
So expansion of the money supply relative to the supply of goods and services is necessary and sufficient to explain inflation. What therefore is the question the Phillips curve and other such things are useful for answering?