通胀的言下之意？

For a central bank to keep unemployment below the natural rate, it must keep outdoing itself, delivering inflation surprise after inflation surprise. Hence, Friedman reasoned, Keynesians were wrong to pin a low rate of unemployment to a given, high rate of inflation.

对于想把失业率维持在自然比率之下的央行来说，它必须保持不断地超越自身，传递出一个又一个的通胀惊奇。因而，弗里德曼分析道，凯恩斯主义把低失业率与给定的、高通胀率相挂钩是错误的。

To sustain unemployment even a little below the natural rate, inflation would need to accelerate year in, year out. Friedman’s and Phelps’s natural rate became known as the “non-accelerating inflation rate of unemployment” (NAIRU).

要想把失业率维持在哪怕是比自然比率低一点的地方，通胀也必需不断加速。弗里德曼和菲尔普斯的自然比率已成为众所周知的“非加速通胀型失业比率”(non-accelerating inflation rate of unemployment 简称NAIRU)。

No society could tolerate endlessly rising, or falling, inflation. Phillips had observed a correlation in the data, but it was not one that policymakers could exploit in the long run. “There is always a temporary trade-off between inflation and unemployment,” Friedman said. “There is no permanent trade-off.” Nearly 50 years on, that remains the premise on which rich-world central banks operate.

没有社会可能容忍上蹿下跳的通胀。菲利浦斯在数据中找到了一种关联，却不是决策者可以长期利用的那种。 “在通胀和失业之间，有的总是一种暂时的取舍，”弗里德曼说，“没有永久的取舍”。将近50年以后，这仍然是富裕世界的央行以之运作的前提。

When officials talk about the Phillips curve, they mean Friedman’s temporary trade-off. In the long run, they believe, unemployment will come to rest at the natural rate.

当官员们谈论菲利普斯曲线时，指的是弗里德曼的暂时取舍。他们坚信，从长期来看，失业率终将止息于自然比率。

The idea has such influence partly because Friedman’s and Phelps’s contributions were so well timed. Before 1968, America had had two years with unemployment below 4% and inflation below 3%. But when Friedman spoke, prices were indeed accelerating; inflation rose to 4.2% in 1968.

这种思想之所以有如此的影响力，部分是因为弗里德曼和菲尔普斯的贡献正合时宜。1968年之前，美国曾经有两年失业低于4%、通胀低于3%。但是，弗里德曼讲话时，物价的确是在加速；1968年，通胀上涨到了4.2%。