A. W. Phillips proposed the curve linking unemployment and wage inflation in a 1958 study of the United Kingdom.
In his paper, New Zealand-born economist Alban William Phillips examined British data from 1861 to 1957. He reported an inverse relationship between unemployment and the rate at which money wages changed: wage growth tended to be higher when unemployment was low and lower when unemployment was high.
Economists later adapted the relationship to connect unemployment with price inflation. The Phillips curve became influential in debates over whether policymakers could permanently trade higher inflation for lower unemployment. Milton Friedman and Edmund Phelps argued that expectations matter and that such a trade-off cannot be permanently maintained.
The original study concerned wage changes, not a universal law guaranteeing a fixed exchange between inflation and unemployment. Supply shocks, changing expectations, productivity, and institutional conditions can all shift or weaken the observed relationship.