To judge by Yellen’s recent speeches, the Fed may no longer believe in any version of the “natural” unemployment rate. Friedman’s assumptions of ever-accelerating inflation and irrationally “rational” expectations that lead to single-minded targeting of price stability remain embedded in official economic models like some Biblical creation myth.
但美联储的克制也有可能出于一个更深层次的原因。由耶伦近期的讲话判断，美联储可能不再相信任何版本的“自然”失业率了。导致一心关注物价稳定的弗里德曼长期加速通胀假设和非理性的“理性”预期依然如圣经创世神话那样深植在官方的经济模型中。但美联储，与几乎所有他家央行一道，显得已经对这个神话失去了信仰。