金融海嘯過後 經濟學教科書「落伍了」

來源: 公民與社會

作者:經濟學人  出處:天下雜誌 444期 2010/04
相關關鍵字:經濟學人

這場金融危機影響深遠,現在連美國頂尖大學的經濟學教材與授課方式,都要大變身。還在念舊版的教科書嗎?專家都說,那落伍了。

教了三十幾年的總體經濟學導論,普林斯頓大學教授布蘭德從沒看過學生的上課興趣,像去年這麼高。哈佛大學教授萊卜森也形容,他的學生現在都「迫不及待」要聽他開講。

學生們對經濟學的興趣大增,是這些頂尖大學在衰退困境中,意外的驚喜。然而,這次金融危機卻也暴露出總體經濟學教科書的「落伍」問題。

暢銷教科書《經濟學原理》作者、哈佛教授曼昆直言,學生要是對金融業的角色一無所知,如何搞懂這場危機的前因後果?他打算修改自己的書,明年以新版上市。布蘭德也批評,大部份入門書即使提到了「金融體系」,通常也只談貨幣供需,學生對於金融危機的種種疑問,「現在的課程教法,甚至連個不完美的答案,都給不出來。」

因此,布蘭德也在修改他自己跟人合寫的教科書,新版預計在六月推出,書中將詳細解釋「槓桿操作」(leverage),以及這種操作如何釀成了金融危機。

經過這麼一改,難免會增加難度,例如,證券化與系統性風險等問題,大學生也許不容易掌握,但布蘭德卻認為有必要探討。他引用愛因斯坦的名言,提醒經濟學家謹記:「凡事都應盡可能簡化,但不能過於簡單。」

另一位總經教科書作者、史丹佛大學教授鍾斯,原本替自己的書補充了兩章的新內容,但現在乾脆把這兩章提到的重要觀念,整合到全書中。

不僅這樣,全美許多一流大學的經濟學課程也都在調整。哈佛的萊卜森說,他已經決定不用任何標準教材來授課。麻省理工學院教授吉亞瓦齊則是把四○%的授課時間,都用來討論金融危機如何改變經濟,以及當利率跌到零,財經政策的效果會有什麼不同。

原本常被大學部課程打入冷宮的「流動性陷阱」(指利率持續走低下,寬鬆貨幣政策宣告失效),現在又熱門起來;資產泡沫的問題也大受學生歡迎。

這些經濟學的教學變革,影響力能否持久?至少,重新編寫常用教科書,可以確保某些詮釋這次危機的重要觀念,成為未來課程的一部份。鍾斯建議,不妨在十年後,把那時最暢銷的教科書,拿來跟曼昆的舊版《經濟學原理》比一比,他相信兩者將大不同。(吳怡靜譯)

原文如下
Economics textbooks

By The Economist print edition
From The Economist  Published: April 09, 2010

IN MORE than 30 years of teaching introductory macroeconomics, says Alan Blinder of Princeton University, he has never seen interest as high as it was last year. At Harvard, says David Laibson, students in his undergraduate macroeconomics course are “chomping at the bit”. At elite American universities, where endowments have shrivelled and hiring is down, increased interest in economics is among the most benign of the recession’s effects.

Yet the crisis has also highlighted flaws in the existing macroeconomics curriculum. Greg Mankiw, a Harvard economist and the author of a bestselling textbook, points out that students can hardly be expected to make sense of the crisis if they know virtually nothing about things like the role of financial institutions. Yet if there is a “financial system” in most introductory texts, Mr Blinder observes, it usually focuses on the demand and supply functions for money. “The current curriculum fails to give students even imperfect answers” to their legitimate questions about recent economic events, he says.

Changes are coming. Mr Blinder is one of the authors of another popular undergraduate textbook, which he is now revising. In the process, he is having to think long and hard about how to balance the need for more detail about things like finance with the constraints under which introductory macroeconomic courses are taught. The new edition is likely to have a prominent place for the idea of leverage and how it contributed to the crisis. That is fairly simply explained. But some additional complexity will be unavoidable.

For instance, the convenient fiction of a model of the economy with a single interest rate was defensible as long as different rates moved in concert. This, Mr Blinder says, is no longer something that students can be told “with a straight face”. Some discussion of the role of securitisation and systemic risk is essential, even if it feels like a lot of detail for beginners to grasp. Mr Blinder, with a nod to Albert Einstein, says that economists need to remember that things should be made as simple as possible, but no simpler.

Revised textbooks will soon find their way into bookshops. Charles Jones of Stanford University has put out an update of his textbook with two new chapters designed to help students think through the crisis, and is now working on incorporating these ideas into the body of the book. A new edition of Mr Mankiw’s book should be out in about a year. And Mr Blinder’s publishers aim to have his revised text on sale by June.

Courses in many leading universities are already being amended. Mr Laibson says he has chosen to teach his course without leaning on any standard texts. Francesco Giavazzi of the Massachusetts Institute of Technology is now devoting about two-fifths of the semester’s classes to talking about how things are different during a crisis, and how the effects of policy differ when the economy hits boundaries like zero interest rates. Discussion of the “liquidity trap”, in which standard easing of monetary policy may cease to have any effect, had fallen out of vogue in undergraduate courses but seems to be back with a vengeance. Asset-price bubbles are also gaining more prominence.

Will these changes in the way macroeconomics is taught really stick? The rewriting of widely used texts should ensure that some of the ideas that have helped explain the crisis become part of the future curriculum. Mr Jones says it will be instructive to compare the bestselling textbook in ten years’ time with the pre-crisis version of Mr Mankiw’s book. He thinks they will differ substantially.

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