超低利率不是央行的陰謀

Why are interest rates so low? The best answer is that the advanced countries are still in a “managed depression”. This malady is deep. It will not end soon.

當前利率爲何如此之低？最佳答案是，發達國家仍處於一種“可管理的蕭條”之中。這種蕭條非常嚴重，它不會很快結束。

One can identify three different respects in which interest rates on “safe” securities in the principal high-income monetary areas (the US, the eurozone, Japan and the UK) are exceptionally low. First, the short-term intervention rates of central banks are 0.5 per cent or lower. Second, yields on conventional long-term government bonds are extremely low: the German 30-year bond yields 0.7 per cent, the Japanese close to 1.5 per cent, the UK 2.4 per cent and the US 2.6 per cent. Finally, long-term real interest rates are minimal: UK index-linked 10-year gilts yield minus 0.7 per cent; US equivalents yield more, but still only plus 0.4 per cent.

人們可以發現，主要高收入貨幣區（美國、歐元區、日本和英國）的“安全”證券利率異常低表現在三個不同方面。首先，央行的短期干預利率是0.5%甚至更低。其次，長期政府債券的收益率極低：德國30年債券收益率爲0.7%，日本接近1.5%，英國是2.4%，美國是2.6%。最後，長期實際利率也非常低：英國十年期通脹掛鉤國債收益率爲-0.7%，美國同類債券收益率高一些，但也只有0.4%。

If you had told people a decade ago that this would be today’s reality, most would have concluded that you were mad. The only way for you to be right would be if demand, output and inflation were to be deeply depressed — and expected to remain so. Indeed, the fact that vigorous programmes of monetary stimulus have produced such meagre increases in output and inflation indicates just how weak economies now are.

如果你在十年前告訴人們，今天會出現上述這些情況，大多數人會認爲你瘋了。只有需求、產出和通脹全都極度低迷，並且人們預期這種低迷還會持續下去，你的預言纔有可能成真。實際上，力度極大的貨幣刺激措施給產出和通脹帶來的增幅非常小，可見當前經濟多麼疲弱。

Yet today we hear a different explanation for why interest rates are so low: it is the fault of monetary policy — and especially of quantitative easing, the purchase of long-term assets by central banks. Such “money printing” is deemed especially irresponsible.

然而，現在我們聽到了關於利率極低的不同解釋：它是貨幣政策（尤其是央行購買長期資產這類量化寬鬆政策）的錯。有些人認爲此類“印鈔行爲”特別不負責任。

As Ben Broadbent, deputy governor of the Bank of England, has argued, this critique makes little sense. If monetary policy had been irresponsibly loose for at least six years — let alone, as some have argued, since the early 2000s — one would surely have seen inflationary overheating, or at least rising inflation expectations. Moreover, central banks cannot set long-term rates wherever they wish. Empirical analysis of the impact of quantitative easing suggests it might have lowered bond yields by as much as a percentage point. But note that yields remained extremely low even well after QE ended, first in the UK and now in the US.

正如英國央行(Bank of England)副行長本•布羅德本特(Ben Broadbent)所說的，這種指責毫無道理。如果貨幣政策在至少6年時間裏——還有些人說是自本世紀初以來——保持一種不負責任的寬鬆，人們肯定會看到通脹飆升，或者至少是通脹預期不斷上升。此外，央行不可能隨心所欲地制定長期利率。對量化寬鬆效果的實證分析表明，它可能將債券收益率拉低了1個百分點。但請注意，即便在量化寬鬆政策結束之後（先是英國，現在是美國），收益率依然保持了極低的水平。

The price level is the economic variable that monetary policy influences most strongly. Central bankers cannot determine the level of real variables — such as output, employment, or even real interest rates (which measure the return on an asset after adjusting for inflation). This is especially true over the long run. Yet the slide in real interest rates is longstanding. As measured by index-linked gilts, they fell from about 4 per cent before 1997, to about 2 per cent between 1999 (after the Asian financial crisis) and 2007, and then towards zero (in the aftermath of the western financial crisis).

物價水平是受貨幣政策影響最明顯的經濟變量。央行家們不可能決定實際經濟變量的水平，比如產出、就業，甚至是實際利率，後者衡量的是經通脹調整後的資產回報率。長期而言尤其如此。然而實際利率的下降是長期性的。以通脹掛鉤債券衡量，它們的收益率從1997年以前的4%左右，降至1999年（亞洲金融危機爆發之後）至2007年間的2%左右，隨後又降至接近零的水平（西方金融危機爆發之後）。

There is a more convincing story about why interest rates are so low. It is that the equilibrium real interest rate — crudely, the interest rate at which demand matches potential supply in the economy as a whole — has fallen, and that central bankers have responded by cutting the nominal rates they control. Lawrence Summers, former US Treasury secretary, has labelled the forces “secular stagnation” — by which is meant a tendency towards chronically deficient demand.

利率極低的原因有更令人信服的解釋。那就是，均衡實際利率——簡單地說，就是整體經濟中需求與潛在供給相匹配時的利率——已經下降，央行行長通過降低他們控制的名義利率來應對。美國前財政部長勞倫斯•薩默斯(Lawrence Summers)將這種狀況稱爲“長期停滯”(secular stagnation)，意指長期性需求不足的趨勢。

The most plausible explanation lies in a glut of savings and a dearth of good investment projects. These were accompanied by a pre-crisis rise in global current account imbalances and a post-crisis overhang of financial stresses and bad debt. The explosions in private credit seen before the crisis were how central banks sustained demand in a demand-deficient world. Without them, we would have seen something similar to today’s malaise sooner.

最合理的解釋是儲蓄過剩和缺乏良好的投資項目。伴隨着這些問題，金融危機前全球經常賬戶失衡加劇，危機後金融壓力和不良債務問題嚴重。危機前出現的私人信貸激增，顯示了在一個需求不足的世界，央行怎樣維持需求。如果不是它們，我們會更早看到與今日類似的低迷景象。

Since the crisis, central banks have not chosen how to act — their hands have been forced. Events in the eurozone provide a powerful example. In early 2011, the European Central Bank raised its intervention rate from 1 to 1.5 per cent. This was wildly inappropriate, and in the end the ECB had to cut rates again and embark on QE. If central banks are to be a stabilising force, they have to move interest rates in an equilibrating direction — and that direction is not something they can choose.

危機爆發以來，各國央行沒有選擇如何行動——它們的手一直被壓着。歐元區發生的事提供了一個有力例證。2011年初，歐洲央行(European Central Bank)將干預利率從1%上調到1.5%。此舉極爲不妥，歐洲央行最後不得不再次降息，並開始採取量化寬鬆。如果央行想成爲一個起到穩定作用的力量，它們就得按照一個平衡的方向調整利率——而這個方向還不是它們能選擇的。

Rising risk aversion might be another reason why real interest rates on safe securities have fallen. The idea is that the crises increased the appeal of the safest and most liquid assets. This is part of the explanation for ultra-low yields on German Bunds. But it does not seem to be the dominant explanation over the longer run. The gap between the interest rate on treasuries and US corporate bonds has not been consistently wider since the crisis, for example.

厭惡風險心理加重可能是安全證券實際利率出現下降的另一個原因。因爲金融危機增加了最安全以及流動性最強的資產的吸引力。這在一定程度上解釋了爲什麼德國國債的收益率極低。但從長期角度來看，這似乎不是一個主要因素。比如自金融危機以來，美國國債和企業債券之間的息差並不是一直都比較大。

We should view central banks not as masters of the world economy, but as apes on a treadmill. They are able to balance demand with potential supply in high-income countries only by adopting ultra-easy policies that have destabilising consequences down the line.

我們不該將央行看作是全球經濟的主宰，而應將它們看成在一臺跑步機上奔跑的猩猩。它們只有採用超寬鬆的政策，才能在高收入國家平衡潛在供給與需求之間的關係，但這些政策會在各個方面產生不穩定的後果。

When will we see an enduring rise in real and nominal interest rates? That would require a marked strengthening of investment, a marked fall in savings and a marked decline in risk aversion — all unlikely in the near future. China is slowing, which is likely to depress interest rates further. Many emerging economies are also weakening. The US recovery might not withstand significantly higher rates, particularly given the dollar’s current strength. Debt also remains high in many economies.

什麼時候我們才能看到實際利率和名義利率出現持續上升？這將需要投資明顯加強，儲蓄明顯減少以及避險意識明顯下降，所有這些在近期都不大可能發生。中國經濟正在放緩，這很可能進一步抑制利率。許多新興經濟體也在變得疲弱。美國的經濟復甦可能無法承受利率大幅提高，尤其是考慮到美元目前的強勢。許多經濟體的債務負擔仍很重。

Ultra-low interest rates are not a plot by central bankers. They are a consequence of contractionary forces in the world economy. While upward moves in rates seem ultimately inevitable from current levels, it is likely that historically low rates will be with us for quite a while. Those who bet on jumps in inflation and a bond-market rout will continue to be disappointed. The depression has been contained. But it is a depression, all the same.

超低利率不是央行的陰謀，而是緊縮性力量在全球經濟中製造的後果。雖然利率上行最終是不可避免的，但處在歷史低點的利率很可能將伴隨我們很長一段時間。那些打賭通脹會飆升、債券市場會崩潰的人仍將失望。蕭條已經得到了遏制，但蕭條畢竟是蕭條。