我大略讀了一下克魯曼 2012 年的一篇相關論文（Gauti B. Eggertsson and Paul Krugman, "Debt, Deleveraging, and the liquidity trap: A Fisher-Minsky-Koo Approach," The Quarterly Journal of Economics, (2012), 1469–1513.）這一篇論文的結論基本上是在支持辜朝明的主要論點：（1）當民間企業普遍地遭遇到劇烈的資產大幅縮水，的確會造成總體經濟運作不良，因而必須要有人擴大支出來彌補負債者支出的大幅縮水；而資產縮水的幅度如果夠大，的確有可能連零利率都不足以激發出所需要的擴大支出；（2）這種情境下的經濟復甦確實很接近辜朝明所描述的「資產負債表式衰退」;（3）在這種情境下，政府正確規劃的短期財政擴大支出不但不會排擠民間支出，還會帶動民間支出的擴張，而加速帶領經濟體走出困境。底下是海外台籍經濟學者的完整來函。
-------------------------- 一位海外經濟學者的來函 --------------------------
Just last October (yes, less than 3 months ago), IMF admitted publically they had errored in calculation of fiscal multipliers. They now say multipliers are large, 1.5 on average. It is qute unusal for such a conservative ( or ideological, according to some liberals) organization to swallow their pride and admit their mistake. Actually this is probably the most important news among macroeconomists in 2012. The following is a comment by Gavyn Davies, a senior editor of Financial Times in
"Nothing in economics is more potent than a simple idea whose time has come. Illustrating this maxim, a three-page article in the IMF’s latest World Economic Outlook promises to have a greater effect on global economic policy than all of the interminable meetings held at the annual meetings of the IMF and the World Bank in Tokyo a week ago.
That article, written by IMF chief economist Olivier Blanchard and Daniel Leigh, presented evidence that the fiscal multiplier in the advanced economies is considerably larger than had been assumed..."
Keynes followers like Paul Krugman has declared that Keynes is biggest winner in the history of Macroeconomics. (google IMF, multipliers......, you will find some interesting articles)
Krugman revised this idea that increasing inflation expectation can save the world out of the liduidity trap we are in in the very early stage of the Financial Crisis. He has been arguing that increasing inflation expectation is a second best policy choice at best and, more importantly, like Stiglitz, that fiscal policy is more powerful than monetary policy. This is the main driving thesis of his most recent book: End This Depression Now. Yesterday he ridiculed people advocating austerity policy by saying:
"Usually I’m criticizing the kind of people who believe that deficits are terrible, awful, and therefore that slashing deficits now now now will promote recovery — when it would actually kill it".
And if monetary is more potent than fiscal policy, how on earth we have this kind of threat like Fiscal Cliff - a term coninaged by Ben Bernanke? Ben knows it quite wll that there are limitations to monetary policy.
My judgement is that Koo got about 80% right. The difference between Krugman and Koo is Mr Koo completely dislikes monetary policy (QE, inflation expectation etc) while Krugman (or Stiglitz and other liberals like me) say loose monetary policy helps but takes longer time to dig us out of this trap.