Typically, the two are equal, and, if not, powerful forces push them towards each other. But, with high and persistent levels of unemployment in the United States, there is a real question about the nature of the problem: is aggregate demand too low, or are there problems with supply?
芝加哥——经济学的全部内容就是需求与供给。 供需一般相互平衡，否则的话就会产生强大的力量让两者相互靠近。 但美国失业率长期居高不下意味着供需出现了本质性问题： 是总需求太低，还是供给出现了问题？