世界抵達貨幣政策的極限了嗎

Have we reached the limits of monetary policy? No. The central banks’ medicine cabinet is still full. Yet using the old treatments more aggressively or using altogether new treatments creates political, financial and economic risks. Worse, such action cannot solve some of the bigger difficulties the high-income economies confront. In an ideal world, therefore, monetary policy, should not remain “the only game in town”, as the title of a book by the economist and investment manager Mohamed El-Erian suggests it now is. Unfortunately, we do not live in an ideal world. In the real world, central banks must remain our doctors of choice.

我們已到達貨幣政策的極限了嗎？沒有。中央銀行的藥箱仍是滿滿的。不過，更激進地使用舊療法，或者使用全新療法，都會產生政治、金融和經濟風險。更糟糕的是，這麼做無法解決高收入經濟體面對的一些更大的難題。因此，在理想世界中，貨幣政策不應繼續是“唯一的選擇”（經濟學家、投資經理穆罕默德•埃爾-埃利安(Mohamed El-Erian)所著《唯一的選擇》(The Only Game in Town)的書名暗示，當前情形恰恰如此）。遺憾的是，我們並非生活在理想的世界裏。在現實世界中，央行必須繼續充當我們的首選醫生。

Central banks have duly employed more radical treatments than ever before. All the leading central banks of advanced economies have set short-term intervention rates close to zero. The Bank of Japan has applied rates this low since 1995. The US Federal Reserve and the Bank of England have used ultra-low rates since early 2009. By 2013, the European Central Bank followed suit — albeit too slowly.

各國央行已正確地採取了比以往任何時候都要激進的療法。主要發達經濟體的央行都把短期干預利率設置爲接近零的水平。自1995年以來，日本央行(BoJ)一直把利率維持在這麼低的水平。自2009年初以來，美聯儲(Fed)和英國央行(BoE)一直採取超低利率政策。到2013年，歐洲央行(ECB)也開始跟進，儘管動作太晚了。

These central banks have also substantially expanded their balance sheets through quantitative easing or, in the case of the Bank of Japan, “quantitative and qualitative easing” (which includes lengthening of the maturity of the assets it buys). Like the Fed, the Bank of England has stopped purchasing assets. But its balance sheet is bigger, relative to UK gross domestic product, than throughout its long history. The BoJ and ECB are still expanding their balance sheets today (see charts).

這些央行還通過量化寬鬆——日本央行則採取“量化兼質化寬鬆”（包括延長所購資產的期限）——大幅擴大了自己的資產負債表。與美聯儲一樣，英國央行已停止購買資產。但是，英國央行資產負債表相對英國國內生產總值(GDP)的比例，已達其史上最高。日本央行和歐洲央行目前仍在擴大自身資產負債表（參見圖表）。

More recently, as Mark Carney, governor of the Bank of England, noted in Shanghai in February: “Central bank innovation has … extended to negative rates, with around a quarter of global output produced in economies where policy rates are literally through the floor.”

正如英國央行行長馬克•卡尼(Mark Carney) 2月在上海所指出的：“央行的創新已……擴展到負利率，全球產出中大約有四分之一是政策利率低於零的經濟體創造出來的。”

Yet, even after years of such effort, the US is the only significant high-income economy to have achieved its target rate of core consumer price inflation. That is also why the Fed alone has started a tightening cycle, albeit in a gingerly fashion, with the federal funds rate still below 0.5 per cent.

然而，即便經過多年的如此努力，美國仍是唯一實現核心消費價格通脹率目標的重要高收入經濟體。也正因爲如此，唯有美聯儲啓動了緊縮週期，不過動作小心翼翼，聯邦基金利率現在仍低於0.5%。

One response to this apparent failure is the argument that hitting the inflation target does not matter. Some even argue that deflation has merits. This view is flawed, for three reasons.

針對這一明顯失敗，有人提出了達成通脹率目標並不重要的觀點。有些人甚至辯稱，通縮也有好處。這一看法是錯誤的，原因有三。

First, if inflation is zero or, still worse, if it turns negative, it becomes harder to secure needed changes in relative prices and wages. The obstacle here is nominal wage rigidity. This difficulty is particularly important in a multi-country currency union, such as the eurozone.

第一，如果通脹率爲0，或者更糟，通脹率變爲負值，那麼我們將更難實現相對物價和工資的必要變化。這裏的障礙是名義工資剛性。這一難題在歐元區這樣的多國貨幣聯盟尤爲突出。

Second, under deflation negative real interest rates are possible only with strongly negative nominal interest rates. Without negative real interest rates, countries might end up in a prolonged period of deficient demand, elevated unemployment and weak investment.

第二，在通縮情況下，只有顯著低於零的名義負利率才能產生實際負利率。若沒有實際負利率，各國或許最終會陷入更長期的需求不足、失業率升高和投資不振。

Third, under deflation the real burden implied by a given level of nominal debt spirals upwards. This risks creating “debt deflation”, a condition explained by the US economist, Irving Fisher, in the 1930s. While Japan managed to stabilise deflation at a slow rate, this may be due to its aggressive use of fiscal policy. With the latter ruled out in the eurozone, the risks of accelerating deflation might be even greater there.

第三，在通縮情況下，給定水平名義債務所隱含的實際債務負擔會螺旋式上升。這就可能產生“債務通縮”，美國經濟學家歐文•費雪(Irving Fisher)在1930年代解釋過這種情況。儘管日本成功地把通縮穩定在低水平上，但這可能是該國積極使用財政政策的結果。由於歐元區排除了財政政策，那裏通縮加速的風險或許會更高。

It is important, then, for central banks to hit their inflation targets. This entails very low, or even negative, nominal rates. As Mario Draghi, president of the ECB, explained in a recent speech, many complain that these low interest rates are themselves the problem. “But,” he responds, “they are not the problem. They are the symptom of an underlying problem, which is insufficient investment demand, across the world, to absorb all the savings available in the economy.”

因此，央行達成通脹率目標非常重要。這需要很低、甚至負值的名義利率。正如歐洲央行行長馬里奧•德拉吉(Mario Draghi)在不久前一次演講中所解釋的那樣，許多人抱怨稱，低利率本身就是問題所在。“但是，”他回答說，“低利率本身並不是問題，而是另一個深層次問題的表象，那就是全球投資需求不足，無法吸收經濟中的全部儲蓄。”

The question is how well monetary policy can remedy such a chronical deficiency in demand. One answer is that central banks possess many ways of delivering further monetary stimulus: low and even negative interest rates, asset purchases, forward guidance, higher inflation targets, outright monetary financing of government deficits, and direct dispatch of money to households.

問題在於，貨幣政策能在多大程度上解決長期需求不足的難題。一個答案是，央行擁有提供進一步貨幣刺激的多種手段：低利率甚至負利率、資產購買、前瞻指引、提高通脹率目標、直接爲政府赤字提供貨幣融資，以及直接向家庭派發現金。

In recent blogs, Ben Bernanke, former chairman of the Fed, demonstrates the potency of such tools. He could even be too cautious about how low negative rates can go, arguing that “beyond a certain point, people will just choose to hold currency, which pays zero interest”. But creating a payment system based on cash is a difficult and expensive task. More fundamentally, as Martin Sandbu has argued, it would be possible for the central bank or the banks to limit access to cash or impose charges on converting deposits into cash. Some economists even recommend abolishing cash.

在不久前的博客文章中，美聯儲前主席本•伯南克(Ben Bernanke)闡釋了這些工具的強大作用。對於負利率可能低到什麼程度，他甚至可能太過謹慎了，他說，“超過某個臨界點後，人們將選擇持有貨幣，利率爲零”。但是，創建一種基於現金的支付系統，是一項艱難且成本高昂的任務。更根本的問題是，正如馬丁•桑德布(Martin Sandbu)所指出的那樣，央行或普通銀行有可能限制人們取現、或者對存款取現收費。有些經濟學家甚至建議取消現金。

Nevertheless, going further does run into significant difficulties.

不過，進一步採取貨幣政策的確會遇到重大困難。

First, the more unconventional the policy, the more difficult it is to calibrate its effects. It is necessary to create just enough additional demand, but not too much, along with manageable side effects. This is quite hard to do, not least because monetary policy works via many channels. Moreover, the effects can be unpredictable. Do negative rates, for example, increase confidence by showing that central banks are not out of ammunition, or damage it by proving how bad the illness is?

第一，貨幣政策越是非常規，衡量其效果的難度越大。有必要創造剛好足夠的額外需求，但又不能創造太多需求，同時要讓副作用處於可控範圍。做到這一點是相當困難的，重要原因在於，貨幣政策是通過多條渠道發生作用的。另外，影響可能是不可預測的。比如說，負利率到底會因表明央行並未耗盡彈藥而增強信心，還是會因證明病症有多麼嚴重而削弱信心？

Second, some remedies might be worse than the disease. Perhaps the biggest concern is that extreme monetary policy risks distorting asset prices and generating new financial bubbles. Another critique is that reliance on monetary policy treatmentsrelieves pressure on governments to conduct necessary structural reforms. Again, policies apparently designed to affect the exchange rate could be viewed as beggar-my-neighbour devices.

第二，有些療法或許會比疾病更有害。最令人擔心的或許是，極端貨幣政策可能扭曲資產價格，並引發新的金融泡沫。另一種批評是，依賴貨幣政策療法會減輕政府執行必要結構性改革的壓力。此外，明顯旨在影響匯率的政策可能被視爲以鄰爲壑的勾當。

Third, extreme monetary policy runs into political objections. Creditors object to all policies aimed at lowering interest rates, for example. Again, people fear that direct financing of government deficits would merely encourage fiscal profligacy.

第三，極端貨幣政策會遇到政治障礙。比如說，債權人反對一切旨在降息的政策。此外，人們擔心，直接爲政府赤字提供貨幣融資將只會助長財政揮霍。

Apart from these objections, there are two other important difficulties with heavy reliance on monetary policy.

除這三點外，嚴重依賴貨幣政策還有兩大難題。

One of these is that, if the fundamental difficulty is an excess of savings over investment, fiscal policy would be a better targeted remedy. In Japan, for example, the great difficulty has been the excess savings of the non-financial corporate sector. The obvious remedy would be higher taxation of retained profits. Higher taxation of consumption is simply misdirected. An alternative would be for governments to increase spending on high-priority public investments.

其一是，如果根本難題在於儲蓄相對於投資過剩，那麼財政政策將是更有針對性的對策。比如，在日本，非金融企業部門的儲蓄過高一直是個重大難題。顯而易見的對策是提高對留存收益的徵稅。提高消費稅完全是誤入歧途。替代方案將是，政府增加在優先公共投資項目上的支出。

Another objection is that weakness of demand is not the sole difficulty. At least as important is declining growth of productivity and, in a number of countries, the inflexibility of markets. For such reasons, a more complete package should include structural reforms. The latter are not a panacea, particularly in the short term, as theInternational Monetary Fund has noted. But they need to be a part of the mix.

另一條反對理由是，需求不足並非唯一難題。至少同樣重要的難題，是生產率提高的速度在放緩，以及許多國家存在的市場不靈活。出於此類原因，一個更全面的解決方案應當包括結構性改革。正如國際貨幣基金組織(IMF)所指出的那樣，結構性改革不是萬靈丹，尤其在短期內不是。但是，需要把結構性改革作爲政策組合的一部分。

Monetary policy is not exhausted, and active use of it is essential. But undue reliance on monetary policy is problematic.

貨幣政策並未用盡，積極採用貨幣政策是不必可少的。但不適當地依賴貨幣政策，則會帶來問題。

One difficulty lies in the political limits to further action. Another limitation is the need to calibrate policy and mitigate side effects. Fiscal policy should play a far bigger part in demand management. More importantly, monetary policy can palliate, but not cure, structural problems of low growth and inflexible markets. We still need active monetary policy. But it is not all we need

一個難點是，採取進一步的貨幣政策面臨政治障礙。另一個障礙是，需要衡量政策、並減弱副作用。財政政策應在需求管理中扮演重要得多的角色。更重要的是，貨幣政策只能減輕、而不能治癒增長率低和市場不靈活的結構性問題。我們仍需要積極的貨幣政策。但貨幣政策並非我們需要的全部。