简介

雅各布·维纳(Jacob Viner,1892年5月3日- 1970年9月12号)是一位经济学家，并作为现今的芝加哥经济学派的早期成员之一。瓦伊纳出生于1892年在蒙特利尔，魁北克移民父母和罗马尼亚获得了 1914年在麦吉尔大学的学士学位。他在哈佛大学获得博士学位，是当时著名经济理论和国际经济学权威陶西格(Frank W.Taussig,1859~1940)的学生与朋友。

他是从1916年开始在芝加哥大学任教，直至1946年。在不同时候，瓦伊纳还任教于斯坦福大学和耶鲁大学，并两次前往在瑞士日内瓦国际研究学院。1946年，他离开普林斯顿大学，直到1960年退休。

瓦伊纳曾担任芝加哥大学教授，并担任著名的《政治经济学杂志》主编18年之久。他对成本曲线、垄断竞争和寡头市场上的拗折的需求曲线的研究都是开创性的，在经济思想史的研究中也造诣颇深。他影响最大的是关于成本理论的研究和成本曲线的图形表述。这些仍然是今天微观经济学中成本理论的重要内容。

瓦依纳错误

在研究成本理论时，他提出了今天人们都熟悉的包络曲线概念，即长期平均成本曲线是无数条短期平均成本曲线的包络曲线。当时瓦伊纳认为，在长期中企业总可以通过调整生产规模实现平均成本最低，因此，长期平均成本曲线应该是无数条短期平均成本曲线最低点组成的轨迹。根据这种思路，他要求制图员画出一条满足以下两个条件的包络曲线：第一，这条包络曲线要把无数条短期平均成本曲线包在内；第二，这条包络曲线要和所有短期平均成本曲线的最低点相切。

据记载，瓦伊纳的这个制图员是一个中国人(可惜名字已无法考证)，且精通数学。制图员告诉瓦伊纳，这个图是画不出来的，因为在数学上任何一条包络曲线都无法同时满足这两个条件。如果要把无数条曲线包在内，这条包络曲线就不能与这些曲线的最低点相切；如果要使包络曲线与各条曲线的最低点相切，这条包络曲线都不能把各条曲线都包在内。这就说，包络曲线只能满足瓦伊纳要求的两个条件之一，而不能同时满足这两个条件。瓦伊纳为此与制图员发生争吵。

在此之前，经济学家普遍认为，既然长期中企业可以调整规模使平均成本最低，长期平均成本曲线就应该是短期平均成本曲线最低点的轨迹。瓦伊纳的包络曲线概念和对包络曲线两个必须满足的条件的总结正是这种思想的概括。但事实上长期平均成本曲线并不能是各短期平均成本曲线最低点的包络曲线。这种对短期与长期平均成本曲线关系的误解被称为“瓦依纳错误”。是一个不知名的中国制图员纠正了这个错误。

JacobViner

Jacob Viner(May 3, 1892 - September 12, 1970)

Together with Knight, the Canadian-born Jacob Viner was the leading light of the Chicago School of the inter-war period. His work ranged all over economics, but it is perhaps his work on the history of economic thought and international trade theory that we find his remarkable strengths. Nonetheless, as Robbins characterized him, Viner was "the outstanding all-rounder of his time in our profession" (Robbins, 1970: p.2).

Trained by Taussig at Harvard, Viner's very first publication was on methodology (1917), in which he provided a full-fledged defense of the inductive method. His subsequent work was on problems in trade theory (1923, 1924) - a concern which he maintained throughout the rest of his career.

This work was concurrent with his masterly 1921 and 1931 articles on price theory - the first began inching towards a theory of imperfect competition, the second providing an analytical and graphical exposition of the theory of the firm (the long-run and short-run cost curves we see in modern principles textbooks). A famous error on the long-run envelope of short-run average cost curves in his 1931 article and anticipation by Harrod did not diminish his claim to fame.

Jacob Viner was fiercely opposed to the Keynesian Revolution - but not because of its policy prescriptions as indeed, Viner himself had recommended them. As he wrote in several papers (e.g. 1933), he believed the Great Depression was due to deflation in output prices being faster than the collapse in costs. Recovery, he believed, required a restoration of profit margins and thus government-induced inflation - not by monetary expansion, but rather by deficit spending. This would create the necessary price rise,(and, with costs lagging, profits) and the consequent cumulative rise in output to pull the economy out of depression. He was very much a fiscal policy advocate and a believer in policy discretion rather than fixed rules - thus he did not take Milton Friedman's attempt to paint him as an "early Monetarist" very well.

Viner's famous 1936 critique of Keynes was not over policy implications but rather a result of theoretical disputes over liquidity preference and what Viner thought was oversimplified theory of effective demand.　Viner preferred to famously characterize Keynesian theory as "short-run" analysis while considering Neoclassical theory to be true in the "long-run". It was Viner's scathing 1936 critique that prompted J.M. Keynes to write his famous 1937 QJE article as a response.

Viner's work on the history of economic thought began with his 1926 essay on Adam Smith and culminated in his magnum opus, Studies in the Theory of International Trade (1937) - to which we owe most of our knowledge of the Bullionist Controversy in 19th Century Britain - and the masterful introduction to the 1965 reprint of Rae's Life of Adam Smith.

Viner's relations with Knight were cool but respectful. Compared to Knight, Viner was less opposed to quantitative techniques but remained wary of them. A recurring, if pointless, amusement at Chicago was the controversy over cost theory between Knight and Viner - with Knight supporting the Austrian doctrine of opportunity cost and Viner espousing the Marshallian "real cost" theory. This position was, in fact, more than a personal diversion: Viner (1932, 1937), after all, had promoted a "real cost" version of the comparative advantage thesis as opposed to Haberler's "opportunity cost" version or Ohlin's "factor-endowment" version.

Despite being one of the leaders of the Chicago School, Viner left Chicago for Princeton in 1946 - perhaps to the relief of many Chicago first-year students: Viner's "price theory" course was notorious for the terrifying way in which he conducted the classroom discussion. In later years, when questioned as to whether he thought himself part of the Chicago School, his reply was unequivocal:

"I am willing to consider the existence of a 'Chicago School' (but not one confined to the economics department and not embracing all of the department) and that this `School' had been in operation, and had won many able disciples, for years before I left Chicago. But at no time was I consciously a member of it, and it is my vague impression that if there was such a school it did not regard me as a member, or at least as a loyal and qualified member" (Letter to Patinkin, Nov. 24, 1969).