全球經濟需求不足的詛咒

David Cameron, the UK prime minister, states that “red warning lights are once again flashing on the dashboard of the global economy”. The lights are not as red as in 2008. Nevertheless, the difficulties caused by the fiscal austerity that his government recommends have become particularly evident in Japan and the eurozone. These stagnant high-income economies are the weakest links in the world economy. To understand why, one needs to analyse today’s most important economic illness: chronic demand deficiency syndrome.

英國首相戴維•卡梅倫(David Cameron)聲稱，“在全球經濟的儀表板上，紅色警示燈又亮了起來”。這次信號燈沒有2008時那樣紅。然而，財政緊縮——卡梅倫政府也提出實施緊縮政策——引起的困難在日本和歐元區表現得特別明顯。這兩個停滯的高收入經濟體是全球經濟中最薄弱的環節。要理解箇中緣由，有必要分析當前經濟中最重要的病症：慢性需求不足綜合徵。

Jack Lew, US Treasury secretary, provided a sobering overview in a speech delivered in Seattle, en route to last weekend’s summit of the group of 20 leading high-income economies in Australia. As he noted, the world is far from achieving the “strong, sustainable, and balanced” growth, promised at the 2009 summit in Pittsburgh.

最近，美國財長傑克•盧(Jack Lew)去澳大利亞參加全球20個主要高收入經濟體的峯會。他在途經西雅圖時發表了一次演說，他對當前形勢的概述令人警醒。正如他所指出的，世界經濟遠未實現2009年匹茲堡G20峯會承諾的“強勁、可持續、平衡的”增長。

Global recovery has been “uneven, with sharply different trajectories,” he said. “In the US, domestic demand surpassed pre-crisis levels in the first quarter of 2012 and is now about 6 per cent higher than before the crisis. Domestic demand in both Japan and the UK is about 2 per cent higher,” he added. “But demand in the eurozone has yet to recover the ground lost during the crisis, remaining more than 4 per cent below its pre-crisis level.”

全球復甦是“不平衡的，呈現大不相同的軌跡，”他說。“在美國，2012年一季度內需已超過危機前的水平，目前大約比危機前高了6%。日本和英國的內需都比危機前高約2%，”他補充道，“但是，歐元區需求尚未恢復至危機前水平，仍比那時低4%以上。”

What Mr Lew did not add is that this feeble performance – even the 6 per cent rise in real demand in the US over more than six years is pathetic by historical standards – occurred despite the most aggressive monetary policies in history. The official intervention rates of the US Federal Reserve, the European Central Bank and the Bank of England have been not far above zero since late 2008. The ECB struggled to raise rates above 1 per cent in 2011, but then succumbed to the pull of near zero. The Bank of Japan has been offering near zero rates for two decades.

傑克•盧沒有說的是，這一疲軟表現——以歷史標準衡量，美國實際需求在6年多時間裏增加6%都是很差勁的——產生的背景是，全球各主要央行實施了史上最積極的貨幣政策。自2008年末以來，美聯儲(Fed)、歐洲央行(ECB)、英國央行(BoE)的官方干預利率都一直略高於零。2011年，歐洲央行曾勉爲其難地把利率提高到1%以上，但隨後又不得不調回至零附近。過去20年裏，日本央行(BoJ)執行的利率一直接近於零。

Yet this has not been nearly enough. All these central banks have increased their balance sheets sharply. In the US and UK, the balance sheet expansion has stabilised. In the eurozone, the contraction since 2012 is being reversed, while the Bank of Japan’s balance sheet is heading towards the economic stratosphere, at 80 per cent of gross domestic product and counting.

不過，這麼做還遠遠不夠。這些央行都大幅擴張了各自的資產負債表。在美國和英國，央行資產負債表的擴張已穩定下來。在歐元區，自2012年來的收縮正在發生逆轉，日本央行的資產負債表規模與國內生產總值(GDP)的比例已達到80%的極高水平，且在繼續升高。

How do we explain such weak demand, particularly in the eurozone and Japan? Only if we understand this do we have any hope of deciding on the right remedies. One can identify three sets of underlying explanations.

那麼我們該如何解釋爲何需求會如此疲弱，尤其是在歐元區和日本？只有理解這一點，我們纔有希望對症下藥。我們可以歸納出三種基本解釋。

The first set stresses the post-crisis overhang of private debt and the damage to confidence caused by the sudden disintegration of the financial system. The by-now canonical response consists of cleaning up balance sheets and forced injection of capital into the banking system, supported by stress tests, to convince the public that the financial system is again creditworthy. To this should be added fiscal and monetary support for demand. In this view, a return to growth should be swift.

第一種解釋強調後危機時期的鉅額私人債務，以及金融體系突然崩潰對信心的傷害。到目前爲止的典型對策，包括清理資產負債表，強行向金融體系注資，並輔以銀行壓力測試，以使公衆相信，金融體系如今又是可信的。在此基礎上，還應從財政和貨幣方面支持需求。按照這種解釋，恢復增長應該是很迅速的。

The second set of explanations denies this last proposition. It argues that the pre-crisis demand was unsustainable because it relied on huge accumulations of private and public debt – the former associated with bubbles in property prices. Japan suffered such a post-bubble reversal in private debt accumulation after 1990; the US, UK and Spain after 2008. The implication of this is that economies suffer not just from a post-crisis balance-sheet recession, but from an inability to generate credit-driven demand on the pre-crisis scale. Behind the unsustainability of pre-crisis demand lie global imbalances, shifts in income distribution and structurally weak investment. A symptom is a chronic financial surplus (excess of income over spending) in the private sector, as in Japan and the eurozone.

第二種解釋否認了上述看法。它認爲，危機前的需求是不可持續的，因爲當時需求依賴於私人和公共債務的積累——其中前者與房地產泡沫息息相關。日本在1990年後經歷了泡沫破裂後私人債務積累的逆轉；美國、英國和西班牙在2008年後也發生了這種情況。其後果在於，各經濟體不但受困於後危機時期的資產負債表萎縮，而且苦於在後危機時期不能產生像危機前那麼高的、由信貸驅動的需求。危機前需求的不可持續，其根源在於全球失衡、收入分配的變化，以及結構性的投資疲軟。一種症狀就是私人部門長期資金過剩（指收入高於支出的部分），就像日本和歐元區那樣。

The third set of explanations points to a slowdown in potential growth, due to some combination of demographic changes, slowing rises in productivity and weak investment. But this last set of explanations feeds directly into the second. If growth of potential supply is expected to slow, consumption and investment will be weak. That will generate feeble growth in demand. If central banks fight this, they get bubbles. If they accept it, weak growth of supply turns into a self-fulfilling prophecy.

第三種解釋指向了潛在增長率的放緩，其原因在於人口結構變化、生產率增長放慢和投資不足。但是，這最後一種解釋，直接爲第二種提供了支持。如果潛在供給增速預計將放緩，消費和投資也將變弱。這將造成需求增長緩慢。如果央行採取對策扭轉這一狀況，則將催生泡沫。如果央行接受這一狀況，則供給增長疲軟會變成自我實現的預言。

The high-income economies suffer from all three sets of ailments, to a greater or lesser extent: the US less, Japan and the eurozone more. Even China, albeit enjoying a much higher prospective rate of growth, also suffers from the second and third sets of concerns – even if it has not suffered a financial crisis. Its growth of recent years was driven by unsustainably rapid accumulations of debt and unsustainably high rates of investment, given the deceleration in its underlying growth.

高收入經濟體或多或少都患上了這三種病：美國病情輕一些，日本和歐元區病情重一些。就連預期增長率要高得多的中國，也存在第二種和第三種問題，儘管沒有爆發金融危機。就潛在增長率放緩而言，中國近年來的增長驅動力是快速信貸積累和高投資率，而這二者都是不可持續的。

The reason that extreme policy has been so ineffective is that the economies suffer from such deep-seated ailments. It is not just about weak supply. But it is also not just about weak demand. Nor is it just about the debt overhang or financial shocks. Each economy also has a different combination of ailments.

非常政策不太奏效的原因在於，各經濟體患上了上述慢性病。問題不僅在於供給疲軟，也不僅在於需求疲軟。問題也不單純在於鉅額債務或金融危機。每個經濟體還都患上了這樣或那樣的病症。

As a more demographically dynamic and more innovative economy, with low rates of private saving, the chances of escape into normal policy settings are better for the US than for the eurozone or Japan. Similarly, as an economy with catch-up potential, China ought to have a manageable adjustment. But the eurozone and Japan face far bigger challenges in restoring healthy growth. This is because their private sectors are unable to use the savings they wish to generate. This leaves them with unconventional policy choices, probably even more unconventional than those they have tried. The consequences of going further could be politically devastating, particularly in the eurozone. What those possibilities are and why they are so painful will be my topic next week.

作爲一個人口結構更具活力、創新能力更強並且私人儲蓄率低的經濟體，美國迴歸正常政策制定軌道的可能性要大於歐元區和日本。同樣，作爲一個具有追趕潛力的經濟體，中國應當會經歷可以應付的調整。但歐元區和日本要恢復健康增長將面臨更大的挑戰。這是因爲，它們的私人部門無法使用它們希望產生的儲蓄。這讓它們只能採取非常規政策，或許比它們已經嘗試過的更加非常規。那樣的話可能會在政治上造成破壞性影響，對歐元區而言尤爲如此。我將在下一篇文章中討論這些可能性及其痛苦後果。