'리카도의 동등성 정리'에 해당되는 글 1건

  1. [긴축vs성장 ②] GDP 대비 부채비율에서 중요한 건 GDP! 2012.10.21

[긴축vs성장 ②] GDP 대비 부채비율에서 중요한 건 GDP![긴축vs성장 ②] GDP 대비 부채비율에서 중요한 건 GDP!

Posted at 2012.10.21 16:57 | Posted in 경제학/2010 유럽경제위기

이전 포스트 <문제는 과도한 부채가 아니라 긴축이야, 멍청아!> 에서 "경제불황시 부채를 줄이기 위해 긴축정책을 구사하면 부채규모는 더더욱 증가한다."라고 말하는 IMF 세계경제전망보고서(World Economic Outlook)을 다루었다. IMF는 "부채를 줄이기 위해 재정·통화 긴축을 구사하면, 고금리·디플레이션·낮은 경제성장률로 인해 부채규모는 더욱 더 커진다. 오히려 확장적 통화정책이 부채를 축소시킨다." 라고 말한다. 

"아니 그래도 그렇지, 확장정책이 어떻게 부채를 축소시키지? 과다한 빚이 문제면 허리띠를 졸라매야 하는거 아닌가?"라는 물음이 나올 수 있다. 그것에 대한 해답을 찾기 이전에, 부채에 대한 올바른 경제학적 개념정부지출 증가가 어떻게 부채로 인해 생기는 경제적 문제를 해결하는지 알아보자.

※ 부채규모가 큰 것이 문제일까?

현재 경제적 논의의 초점은 과다한 부채에 맞춰져 있다. "가계·국가가 너무 많은 빚을 지고 있기 때문에 경제위기가 발생했고 따라서 해결책은 가계와 국가의 부채를 줄이는 데에 초점을 맞춰야 한다" 라는 것이다. 

그러나 중요한 건, 한 사람의 부채는 다른 사람의 자산이라는 것이다. 

과도한 부채가 문제가 되는 것은 부채규모가 크기 때문이 아니다. 과도한 부채로 인해 한 사람이 디레버리징에 착수하고 소비가 줄어 경제가 불황에 빠지기 때문이다.

소비성향이 높아 레버리징를 활용하는 A, 소비성향이 낮아 레버리징을 하지 않는 B가 있다고 가정하자. A는 레버리징을 통해 신용을 증가시키고 소비를 늘린다. 이와중에 B는 A에게 돈을 빌려주는 역할을 한다. 어느 순간, 부동산시장 폭락 등으로 인해 A가 돈을 더 빌릴 수 없고 디레버리징을 해야하는 시기가 오면 어떻게 될까? A가 디레버리징에 착수하면 경제 내의 소비는 줄어든다. 

그런데 그와중에 경제 전체의 자산 규모는 줄었을까? 경제 전체의 자산규모는 그대로다. 디레버리징을 했는데 전체 경제 내에서 자산은 증가하지 않았다. 다만, 분포가 변했을 뿐이다. 단지 분포만 변한 상태에서 경제 내의 소비는 줄어들었다. 경제가 침체에 빠진 것이다.

과다한 부채가 문제라고 그래서 허리띠를 졸라맸는데, 전체 경제에서 자산이 증가한 것도 아니고 되려 경제침체만 생겼다.

보다못한 정부가 채권발행을 통해 지출을 늘린다. 일자리가 생겨나 A의 소득이 증가하고 A는 다시 소비를 시작한다.

자, 이때 경제 전체의 부채규모는 변했을까? 경제 전체의 부채규모는 그대로다. 다만, 민간부채가 공공부채로 이전했을 뿐이다. 그런데 소비성향이 높은 A가 다시 소비를 시작하면서 경제는 살아나기 시작한다. 경제 전체 내의 부채규모는 변하지 않았는데, 경제침체는 해결됐다. 경제주체의 디레버리징은 경제를 침체에 빠뜨리는데, 이와중에 정부의 빚을 통해 빚으로 인해 생긴 경제침체를 해결할 수 있다. 빚을 빚으로 갚는다는 의미가 바로 이것이다.

그럼 경제를 위해 계속해서 빚을 증가시켜야 하나? 아니다. 다만, 불황에 빠졌을 때 경제주체가 디레버리징을 계속한다면, 경제는 더더욱 불황에 빠진다 라는 것이다.

One of the common arguments against fiscal policy in the current situation – one that sounds sensible – is that debt is the problem, so how can debt be the solution? Households borrowed too much; now you want the government to borrow even more?

What’s wrong with that argument? It assumes, implicitly, that debt is debt – that it doesn’t matter who owes the money. Yet that can’t be right; if it were, we wouldn’t have a problem in the first place. After all, to a first approximation debt is money we owe to ourselves – yes, the US has debt to China etc., but that’s not at the heart of the problem. Ignoring the foreign component, or looking at the world as a whole, the overall level of debt makes no difference to aggregate net worth – one person’s liability is another person’s asset.

It follows that the level of debt matters only if the distribution of net worth matters, if highly indebted players face different constraints from players with low debt. And this means that all debt isn’t created equal – which is why borrowing by some actors now can help cure problems created by excess borrowing by other actors in the past.

To see my point, imagine first a world in which there are only two kinds of people: Spendthrift Sams and Judicious Janets. (Sam and Janet who? If you’d grown up in my place and time, you’d know the answer: Sam and Janet evening / You will see a stranger … But actually, I’m thinking of the two kinds of agent in the Kiyotaki-Moore model.)

In this world, we’ll assume that no real investment is possible, so that loans are made only to finance consumption in excess of income. Specifically, in the past the Sams have borrowed from the Janets to pay for consumption. But now something has happened – say, the collapse of a land bubble – that has forced the Sams to stop borrowing, and indeed to pay down their debt.

For the Sams to do this, of course, the Janets must be prepared to dissave, to run down their assets. What would give them an incentive to do this? The answer is a fall in interest rates. So the normal way the economy would cope with the balance sheet problems of the Sams is through a period of low rates.

But – you probably guessed where I’m going – what if even a zero rate isn’t low enough; that is, low enough to induce enough dissaving on the part of the Janets to match the savings of the Sams? Then we have a problem. I haven’t specified the underlying macroeconomic model, but it seems safe to say that we’d be looking at a depressed real economy and deflationary pressures. And this will be destructive; not only will output be below potential, but depressed incomes and deflation will make it harder for the Sams to pay down their debt.

What can be done? One answer is inflation, if you can get it, which will do two things: it will make it possible to have a negative real interest rate, and it will in itself erode the debt of the Sams. Yes, that will in a way be rewarding their past excesses – but economics is not a morality play.

Oh, and just to go back for a moment to my point about debt not being all the same: yes, inflation erodes the assets of the Janets at the same time, and by the same amount, as it erodes the debt of the Sams. But the Sams are balance-sheet constrained, while the Janets aren’t, so this is a net positive for aggregate demand.

But what if inflation can’t or won’t be delivered?

Well, suppose a third character can come in: Government Gus. Suppose that he can borrow for a while, using the borrowed money to buy useful things like rail tunnels under the Hudson. The true social cost of these things will be very low, because he’ll be putting resources that would otherwise be unemployed to work. And he’ll also make it easier for the Sams to pay down their debt; if he keeps it up long enough, he can bring them to the point where they’re no longer so severely balance-sheet constrained, and further deficit spending is no longer required to achieve full employment.

Yes, private debt will in part have been replaced by public debt – but the point is that debt will have been shifted away from severely balance-sheet-constrained players, so that the economy’s problems will have been reduced even if the overall level of debt hasn’t fallen.

The bottom line, then, is that the plausible-sounding argument that debt can’t cure debt is just wrong. On the contrary, it can – and the alternative is a prolonged period of economic weakness that actually makes the debt problem harder to resolve.


Paul Krugman. "Sam, Janet, and Fiscal Policy". 2010.10.25

※ 실업이 문제일까? 재정적자가 문제일까?

케인지언Keynesian 경제학자를 대표하는 Paul Krugman『End This Depression Now!』를 통해, 현재의 경제위기를 끝내기 위한 통찰력 있는 해법을 제시해준다. 

Paul Krugman은 "재정적자와 국가부채가 문제가 아니라 높은 실업률이 문제! 부채에 신경쓰기보다 실업률을 낮추는 데 신경써야 한다." 라고 말한다.

much of the discussion in Washington had shifted from a focus on unemployment to a focus on debt and deficits.

The strange thing is that there was and is no evidence to support the shift in focus away from jobs and toward deficits. Where the harm done by lack of jobs is real and terrible, the harm done by deficits to a nation like America in its current situation is, for the most part, hypothetical. The quantifiable burden of debt is much smaller than you would imagine from the rhetoric, and warnings about some kind of debt crisis are based on nothing much at all. In fact, the predictions of deficit hawks have been repeatedly falsified by events, while those who argued that deficits are not a problem in a depressed economy have been consistently right.

Paul Krugman. 2012. "But What about the Budget Deficit?". 『End This Depression Now!』. 130-131

※ 유동성함정 하에서 정부지출 증가는 채권금리를 올리지 않는다.

몇몇 경제학자들이 정부지출 증가를 반대하는 이유는 채권 금리를 상승시켜 경제를 불안정하게 만들기 때문이다. 그러나 Paul Krugman은 현재와 같은 유동성함정[각주:1] 하에서는 정부지출 증가가 채권 금리 상승을 불러오지 않는다고 말한다. 되려 현재 경제가 유동성함정에 빠져있기 때문에, 정부지출의 증가가 없다면 경제는 더더욱 침체에 빠질 것이라고 한다.

many people thought and still think about government borrowing: that it must drive up interest rates, because it’s an extra demand for scarce resources— in this case, loans— and this increase in demand will drive up the price. It basically boils down to the question of where the money is coming from. 


in a depressed economy, budget deficits don’t compete with the private sector for funds, and hence don’t lead to soaring interest rates. The government is simply finding a use for the private sector’s excess savings, that is, the excess of what it wants to save over what it is willing to invest. And it was in fact crucial that the government play this role, since without those public deficits the private sector’s attempt to spend less than it earned would have caused a deep depression. 

Paul Krugman. 2012. "But What about the Budget Deficit?". 『End This Depression Now!』. 135-137

실제로 지난 5년간의 확장정책에도 불구하고, 미국의 10년 만기 채권 금리는 오히려 하락했다.

<출처 : Bloomberg's US Generic Govt 10 Year Yield Chart >

 GDP 대비 부채비율에서 중요한 건 GDP !

아무리 높은 실업률이 문제이고 정부지출 증가가 채권금리 상승을 가져오지 않는다고 하더라도, 정부부채를 줄이려는 노력은 해야 하지 않을까?

그런데 GDP 대비 부채비율에서 중요한 건 부채가 아니라 GDP다! 경제성장으로 인해 GDP가 증가하면 GDP 대비 부채비율은 줄어든다. 정부지출을 줄여 현재의 부채크기를 줄이더라도, 정부지출 감소는 미래 소득의 감소도 가지고 온다. 따라서 미래에 부채를 감당할 수 있는 능력만 훼손된다.

In fact, it won’t be a tragedy if the debt actually continues to grow, as long as it grows more slowly than the sum of inflation and economic growth.

To illustrate this point, consider what happened to the $ 241 billion in debt the U.S. government owed at the end of World War II. That doesn’t sound like much by modern standards, but a dollar was worth a lot more back then and the economy was a lot smaller, so this amounted to about 120 percent of GDP (compared with a combined federal, state, and local debt of 93.5 percent of GDP at the end of 2010). How was that debt paid off? The answer is that it wasn’t. 

Instead, the federal government ran roughly balanced budgets over the years that followed. In 1962 the debt was about the same as it had been in 1946. But the ratio of debt to GDP had fallen 60 percent thanks to a combination of mild inflation and substantial economic growth. And the debt-to-GDP ratio kept falling through the 1960s and 1970s even though the U.S. government generally ran modest deficits in that era. It was only when the deficit got much bigger under Ronald Reagan that debt finally started growing faster than GDP. 

Now let’s consider what all this implies for the future burden of the debt we’re building up now. We won’t ever have to pay off the debt; all we’ll have to do is pay enough of the interest on the debt so that the debt grows significantly more slowly than the economy. 

One way to do this would be to pay enough interest so that the real value of the debt— its value adjusted for inflation— stays constant; this would mean that the ratio of debt to GDP would fall steadily as the economy grows. To do this, we’d have to pay the value of the debt multiplied by the real rate of interest— the interest rate minus inflation. And as it happens, the United States sells “inflation-protected securities” that automatically compensate for inflation; the interest rate on these bonds therefore measures the expected real rate of interest on ordinary bonds.


Now think about what this means for the fiscal outlook: even if slashing spending reduces future debt, it may also reduce future income, so that the ability to bear the debt we have— as measured, say, by the ratio of debt to GDP— may actually fall. The attempt to improve the fiscal prospect by cutting spending in a depressed economy can end up being counterproductive even in narrow fiscal terms. Nor is this an outlandish possibility: serious researchers at the International Monetary Fund have looked at the evidence, and they suggest that it’s a real possibility.

Paul Krugman. 2012. "But What about the Budget Deficit?". 『End This Depression Now!』. 140-145

※ 그럼 부채규모 축소 없이 끝없이 부채를 증가시켜야 하나? 

- 경제가 안정 되었을 때 부채를 줄여야한다

확장정책으로 GDP가 증가해 GDP 대비 부채비율이 줄어든다고 하더라도 "그럼 부채의 절대규모를 줄이려는 노력 없이 증가시키기만 해야하나?" 라는 의문은 남아있을 수 있다. 그러나 Paul Krugman은 그런 주장을 하는 것이 아니다. 경제가 침체에서 벗어나 안정기에 접어들었을 때, 부채의 절대규모 축소에 나서는 것이 바람직하다고 말한다.

Finally, even if one took warnings about a looming debt crisis seriously, it was far from clear that immediate fiscal austerity— spending cuts and tax hikes when the economy was already deeply depressed— would help ward that crisis off. It’s one thing to cut spending or raise taxes when the economy is fairly close to full employment, and the central bank is raising rates to head off the risk of inflation. In that situation, spending cuts need not depress the economy, because the central bank can offset their depressing effect by cutting, or at least not raising, interest rates. If the economy is deeply depressed, however, and interest rates are already near zero, spending cuts can’t be offset. So they depress the economy further— and this reduces revenues, wiping out at least part of the attempted deficit reduction.

So even if you were worried about a potential loss of confidence, or at any rate worried about the long-term budget picture, economic logic would seem to suggest that austerity should wait— that there should be plans for longer-term cuts in spending and tax hikes, but that these cuts and hikes should not take effect until the economy was stronger. 

Paul Krugman. 2012. "Austerians". 『End This Depression Now!』. 194

※ 현재의 정부지출 증가가 미래의 세금인상을 불러오지 않을까?

정부지출 증가를 본 경제추제는 미래에 세금이 인상될 것이라고 예측할 수도 있다. 그렇게 된다면, 세금인상을 대비하여 현재의 소비를 늘리지 않는다. 즉, 현재의 정부지출 증가는 경제주체들의 신뢰Confidence를 훼손시키기 때문에 재정정책 효과는 상쇄되고 만다는 것이다. 이것을 리카도의 동등성 정리 Ricardian equivalence proposition 라고 한다. 바로 이런 점 때문에 긴축이 오히려 경제성장을 불러온다는 주장을 확장적 긴축정책Expansionary Austerity 이라 한다.

우리는 정책당국이 아무런 제약 없이 정부지출을 원하는 만큼 증가시키거나 감소시킬 수 있다고 가정하였지만 실제로 이 가정은 옳지 않다. 민간 소비와 마찬가지로 정부 소비에도 예산제약이 존재한다. 이러한 예산제약을 민간의 예산제약과 구분하여 “정부의 예산제약” (government budget constraint)이라고 부른다. 즉 정부소비를 증가시키려면 궁극적으로 정부가 민간으로부터 세금을 더 거두어야 한다. 따라서 현재 정부소비가 증가하면 우리는 (현재에 조세가 증가하지 않으면) 미래에 조세가 증가할 것임을 알 수 있다. 즉 정부지출의 팽창적인 효과가 조세 증가에 의하여 상쇄되는 제3의 밀어내기효과가 존재한다.

조장옥. 2010. "거시경제정책론-재정정책". 『거시경제학』. 639

이에 대해 Paul Krugman은 "5년, 10년 뒤의 세금부담이 얼마나 될지 계산하고 현재의 소비를 줄이는 사람을 본 적이 있느냐?" 라고 비아냥 거린다. 긴축주의자들의 Confidence 타령은 Confidence Fairy 라고 비판한다.

investors, impressed by a government’s effort to reduce its budget deficit, would revise down their expectations about future government borrowing and hence about the future level of interest rates. Because long-term interest rates today reflect expectations about future rates, this expectation of lower future borrowing could lead to lower rates right away. And these lower rates could lead to higher investment spending right away.

Alternatively, austerity now might impress consumers: they could look at the government’s enthusiasm for cutting and conclude that future taxes wouldn’t be as high as they had been expecting. And their belief in a lower tax burden would make them feel richer and spend more, once again right away.

The question, then, wasn’t whether it was possible for austerity to actually expand the economy through these channels; it was whether it was at all plausible to believe that favorable effects through either the interest rate or the expected tax channel would offset the direct depressing effect of lower government spending, particularly under current conditions.

To me, and to many other economists, the answer seemed clear: expansionary austerity was highly implausible in general, and especially given the state of the world as it was in 2010 and remains two years later. To repeat, the key point is that to justify statements like that made by Jean-Claude Trichet to La Repubblica, it’s not enough for these confidence-related effects to exist; they have to be strong enough to more than offset the direct, depressing effects of austerity right now. That was hard to imagine for the interest rate channel, given that rates were already very low at the beginning of 2010 (and are even lower at the time of this writing). As for the effects via expected future taxes, how many people do you know who decide how much they can afford to spend this year by trying to estimate what current fiscal decisions will mean for their taxes five or ten years in the future?

Paul Krugman. 2012. "Austerians". 『End This Depression Now!』. 194-196

  1. 기준금리가 상당히 낮은 수준임에도 불구하고 경제주체가 소비를 늘리지 않는 상황. 금리를 0보다 더 낮은 상태로 내릴 수 없기 때문에 유동성함정에 빠지게 되면 통화정책은 무용지물이 된다. 따라서, 경제가 유동성함정에 빠졌을 때 재정정책의 효과는 커지게 된다. 참고 포스트 http://joohyeon.com/101 [본문으로]

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