"The puzzle and promise of the Phillips curve is the idea that tighter labor markets, traditionally measured by the unemployment rate, correlate with higher wages and prices. That takes more doing. Typically, you have to think that workers are fooled into working for what they think are higher real wages, and only later discover that prices have gone up too. And you have to think that firms rather mechanically raise prices passing on higher labor costs, and keep selling things when they do. Despite the intuitive appeal of tight markets leading to rising prices and wages, that simple intuition is wrong to describe a correlation between tight markets and both prices and wages, which is what the Phillips curve is and was."