Because of its dual mandate from the Congress, which specifies both maximum employment and price stability as policy objectives, the Federal Reserve could not adopt a numerical inflation target as its exclusive goal. Nor would it have been appropriate for the FOMC simply to provide a fixed objective for some measure of employment or unemployment, in parallel with an inflation objective.
In contrast to inflation, which is determined by monetary policy in the longer run, the maximum level of employment that can be sustained over the longer run is determined primarily by nonmonetary factors, such as demographics, the mix of workforce skills, labor market institutions, and advances in technology. Moreover, as these factors evolve, the maximum employment level may change over time.