From John Cochrane:
That paragraph contains a classic economic fallacy, that of composition; the confusion of relative prices and the level of prices and wages overall. If labor markets get “tight,” companies finding it hard to find workers, then yes, one expects wages to rise. But one expects wages to rise relative to prices. You only tempt workers to move to your company by offering them wages that allow them to buy more. Similarly, if there is strong demand for a company’s products, its prices will rise. But those prices rise relative to other prices and to wages. Offering a company higher prices when its wages, costs, and competitor’s prices are all rising does nothing to get it to produce more.
So, in fact, standard economics makes no prediction at all about the relationship between inflation — the level of prices and wages overall; or (better) the value of money — and the tightness or slackness of product and labor markets! The fabled Phillips curve started as a purely empirical observation, with no theory.
To get there, you need some mechanism to fool people — for workers to see their wage rise, but not realize that other wages and prices are also rising; for companies to see their prices rise, but not realize that wages, costs, and competitors’ prices are also rising. You need some mechanism to convert a rise in all prices and wages to a false perception that everyone’s relative prices and wages are rising. There are lots of these mechanisms, and that’s what economic theory of the Phillips curve is all about. The point today: it is not nearly as obvious as newspaper accounts point out. And if central bankers are a bit befuddled by the utter disappearance of the Phillips curve — no discernible relationship, or actually now a relationship of the wrong sign, between inflation and unemployment, well, have a little mercy. Inflation is hard.
There is more at the link.