Federick Mishkin【货币金融学】
Figure 6
The goal of high employment can lead to inflationary monetary policy in another way. Even at full employment, unemployment is always present because of frictions in the labor market, which make it difficult to match workers with employers. An unemployed autoworker in Detroit may not know about a job opening in the electronics industry in California or, even if he or she did, may not want to move or be retrained. So the unemployment rate when there is full employment(the natural rate of unemployment) will be greater than zero. If policymakers set a target for unemployment that is too low because it is less than the natural rate of unemployment, this can set the stage for a higher rate of money growth and a resulting inflation. Again we can show how this can happen using an aggregate supply and demand diagram (see Figure 6).
If policymakers have an unemployment target(say, 4%) that is below the natural rate(estimated to be between 4.5%~5.5% currently), they will try to achieve an output target greater than the natural rate level of output. This target level of output is marked YT in Figure 6. Suppose that we are initially at point 1; the economy is at the natural rate level of output but below the garget level of output YT. To hit the unemployment target of 4%, policymakers enact policies to increase aggregate demand, and the effects of these policies shift the aggregate demand curve until it reaches AD2 and the economy moves to point 1'. Output is at YT, and the 4% unemployment rate goal has been reached.
If the targeted unemployment rate was at the natural rate level between 4.5%~5.5% there would be no problem. However, because at YT the 4% unemployment rate is below the natural rate level, wages will rise and the aggregate supply curve will shift in to AS2, moving the economy from point 1' to point 2. The economy is back at the natural rate of unemployment is again higher than the target level, policymakers would again shift the aggregate demand curve rightward to AD3 to hit the output target at point 2', and the whole process would continue to drive the economy to point 3 and beyond. The overall result is a steadily rising price level——an inflation.
为什么失业率水平低于自然失业率时,工资水平会上升?