Long Run Growth and Functional Finance

Tom Michl has some comments — insightful as always — on the previous post on functional finance. The key point he raises is that we can’t treat the long-run growth rate as given exogenously. Policy that targets current output will also have effects on the long run trajectory that have to be taken into account. He writes:

I’ve become convinced that the real interest rate belongs in the investment equation, g(r), which means that g-r is not something we can just set greater than zero to solve the problem of fiscal deficits. Also that fiscal policy, e.g. the debt ratio, affects the long run position of the IS curve (assuming interest payments go to rentiers who spend them on consumption), so it affects the r that stabilizes inflation.  

The question of exo/endogenous growth is important because a given growth target puts constraints on the feasible fiscal policy, or given fiscal policy, on the ability of a monetary authority to set the inflation-neutral interest rate. 

This is something I’ve heard from other smart people in response to these arguments. [1] I certainly agree with Tom and everyone else that a complete story cannot just take g as given. And I agree that there should be some systematic relationship between the liquidity conditions that we summarize as the interest rate and demand conditions, and the long term growth of income. But it doesn’t seem so straightforward to show that this relationship will be a constraint on the fiscal position.
There are two (sets of) channels: The one Tom mentions here, from financial conditions to investment to growth, and the other, on the supply side from the output gap via the labor supply (hysteresis) or technological change (Verdoorn’s law) to growth. I think the second kind of channel is very important, but it doesn’t create any issues for a functional finance position. It just means that we should define a higher level of output as “full employment” or “price stability.” So let’s focus on the first channel.
We think of investment as additions to the capital stock. Then we have g = s/cdk, where g is the growth rate, s is the average savings rate, c is the incremental capital-output ratio, d is the depreciation rate and k is the average capital-output ratio. This is just accounting. As we know, this accounting relationship is often used to develop the idea of knife-edge instability. But that’s never seemed right to me (and I don’t think it’s what Harrod intended with it.) s is the average savings rate, so in a Keynesian framework it will be a negative function of output. So what this equation is telling us is that if we need to achieve a given growth rate, and the capital-output ratio is fixed, then the output gap will have to adjust so as to get s to satisfy this equation. This is the adjustment that policy is allowing us to avoid. Fiscal policy raises or lowers average s at a given level of income. Monetary policy perhaps raises or lowers s also; more conventionally it is supposed to change the desired capital-output ratio c
So from my point of view, it is not quite correct to say that growth is a function of the interest rate. Rather, variation in the interest rate allows us to reconcile full employment with our chosen growth rate, whatever it may be. 
Now, if we think that interest rates act through the capital-output ratio, then we need that as an additional degree of freedom if we want to combine full employment, our chosen growth rate, and a stable debt-income ratio. As it happens, Peter Skott and Soon Ryoo presented a paper at the Easterns where the requirement to achieve a target capital-output ratio meant that monetary policy was not available to close the output gap, requiring the use of fiscal policy. The additional degree of freedom is supplied by allowing the debt-GDP ratio to evolve freely.  This isn’t a problem in this case. In their model, fiscal policy works through its additions to the stock of assets available to private wealth-owners, not through the flow of demand for currently produced goods and services. So the public-debt GDP ratio will automatically converge to whatever level satisfies the private sector’s demand for net wealth above the capital stock.
So Peter’s paper, I think, addresses Tom’s point. Yes, fiscal policy affects the IS curve. Namely, it moves the IS curve to wherever it needs to be to get full employment at a given growth rate, as long as we are willing to let either the ratio of either capital or debt to output vary endogenously.
The bottom line is that when you move from the short run to the long run you do have to think about growth but that does not necessarily impose any additional constraint. First, if monetary policy operates through the savings rate, then the price stability target already implicitly means price stability at a given growth rate. So the model works the same regardless of what you think the growth rate is or should be. If monetary policy works through the capital-output ratio, then we can no longer say that, but in that case the capital-output ratio itself provides an additional degree of freedom. Only if we impose both a given growth rate and a given capital-output ratio do we possibly foreclose the option of setting r at whatever value is consistent with price stability and a constant debt ratio. And even then, I emphasize “possibly,” because it depends on what you think happens to maintain the constraint. It seems to me the most natural answer is that at some point the desired capital-output ratio becomes insensitive to the interest rate, so, assuming that savings are also insensitive, then full employment cannot be reached at our target growth rate through monetary policy alone. In that case, fiscal policy becomes mandatory. This is where Keynes ended up, more or less, and also the implication of Peter’s paper. But this doesn’t give any argument for why interest rates cannot stay arbitrarily low, it just says that even very low interest rates won’t be sufficiently expansionary to get us to full employment at low growth rates and that fiscal policy or some equivalent will be required as well. Which, as they say, is where we came in.
(I realize that this post probably will not make sense unless you’re already having this conversation.)
[1] Last year’s functional finance post is, thanks to my coauthor Arjun Jayadev, evolving into an academic article; I presented a version at the Eastern Economic Association a few days ago. This was one of the main comments there.

A Response to Tom Palley

Tom Palley wrote a strongly worded critique of Modern Monetary Theory last year, which got a lot of attention int he world of heterodox economics. He has just put up a second piece, MMT: The Emperor Still Has No Clothes, reiterating and extending his criticisms.

Palley is a smart guy who I’ve learned a lot from over the years. But this is not his best work.

By way of preliminaries: MMT consists of three distinct arguments. First is chartalism, the claim that the value of money depends on its acceptability to settle tax obligations. This goes back to G. F. Knapp. Second is functional finance, the claim that government (conceived of as a consolidated budget and monetary authority) seeks to adjust the budget balance to achieve full employment, it can never be prevented from doing so by a financing constraint. This goes back to Abba Lerner and Evsey Domar. And third is the employer of last resort (ELR), a proposal for a specific form of spending to be adjusted under the functional finance rule. This seems to be an original contribution of Warren Mosler goes back to Hyman Minsky.

Personally, I find it useful to set aside the first and third of these arguments and focus on the second, functional finance. My own attempt to restate the functional finance claim in the language of contemporary textbooks is here. In my view, the essential difference between functional finance and orthodoxy is that the assignments of the interest rate and budget instruments are flipped. Instead of setting the interest rate to keep output at potential and setting the budget balance to keep the debt on a sustainable path, we assign the budget balance to keeping output at potential and the interest rate to debt sustainability.

Palley wants to knock down all three planks of MMT. What are his objections to functional finance?

(1) In the absence of economic growth, government deficits will lead to inflation regardless of the output gap. This claim is asserted rather than argued for. [1] It’s not clear what the relevance of this point is, since he agrees that deficits are not inherently inflationary when there is positive growth. Perhaps more importantly, this is a rejection not just as of MMT but of almost all policy-oriented macroeconomics, mainstream and heterodox. Whether you’re reading David Romer or Wendy Carlin or Lance Taylor, you’re going to find a Phillips curve that relates inflation to current output. There are plenty of disagreements about how expected inflation comes in, but nobody is going to include the budget balance as an independent term. In his eagerness to debunk MMT, Palley here finds himself reasserting Milton Friedman-style monetarism.

(2) If we assume an arbitrary floor on spending and an arbitrary ceiling on taxes, then it may be impossible to achieve both full employment/price stability and a sustainable debt path with interest rates fixed at zero. Yes, this is true. But it proves too much: If we impose arbitrary constraints on tax and spending levels then there is no guarantee that we can achieve debt sustainability and price stability with ANY interest rate. At any given interest rate, there is minimum primary balance that must be achieved to keep output at potential. There is also a minimum primary balance that must be achieved to keep the debt-GDP ratio constant. There is no a priori reason to think the first balance is higher than the second. So Palley’s argument here could just as well be a proof that there is nothing government can do to prevent public debt from rising without limit. In any case, these arbitrary limits on taxes and spending are not a feature of standard macro models (including Palley’s own models elsewhere), so it’s hard to justify bringing them in here.

(3) MMT lacks a theory of inflation. On the contrary, MMT has exactly the same theory of inflation as orthodox macro: High or rising inflation is the result of output above potential, disinflation or deflation the result of output below potential. In other words, MMT is consistent with a standard Phillips curve of the same kind Palley (and almost everybody else) uses. To be fair, the Wray and Tymoigne piece Palley is responding to is not as clear as it might be on this point. But Palley is supposed to be writing a critique of MMT, not just of one particular article. And people like Stephanie Kelton state unambiguously that MMT shares the orthodox output-gap story of inflation; see for instance slide 13 here.

(4) MMT doesn’t work in open economies because it requires persistent interest rate differentials between countries. Palley claims that the idea that you can hold interest rates in a given country at zero indefinitely is inconsistent with covered interest parity, a “well-established empirical regularity” that “states there is no room for systematic arbitrage of cross-country interest rates.” It seems that Palley has confused covered and uncovered interest parity. CIP is indeed well established empirically, but it only says that there is no arbitrage possible between the spot and forward markets for a given exchange rate. It does not rule out interest-rate arbitrage in the form of the carry trade, and so does not have any implications for the viability of MMT. If UIP held, that would indeed rule out a persistent zero interest policy in the absence of an equally persistent currency appreciation. But UIP, unlike CIP, gets no empirical support in the literature. Japan has sustained the near-zero interest rates that Palley says are unsustainable for 15 years now, and in general, persistent interest rate differentials without any offsetting exchange rate movements are ubiquitous. Furthermore, if financial openness rules out a policy of i=0, then it equally rules out the use of interest rates as a tool for demand management. The best thing you can say about Palley here is that he is parroting orthodoxy; otherwise he is thoroughly confused.

There is one thing that Palley is right about, which is that substantially all of MMT can be found in the old Keynesian literature. This isn’t news — in the same Stephanie Kelton slideshow linked above, she goes out of her way to say that there is nothing “modern” about MMT. And so what? There’s nothing wrong with updating insights from the past. In my opinion, most useful work in economics is about pouring old wine in new bottles.

I don’t write this from a position within MMT. I tend to feel that the genuine insights of Lernerian functional finance are obscured rather than strengthened by basing them in a chartalist theory of money. It’s fine if Tom Palley disagrees with our friends at UMKC and the Levy Institute. But he needs to put down the blunderbuss.

[1] In fact it’s a bit hard to understand what Palley is claiming here. First he says that “money financed deficits” must lead to inflation in a static economy, even with a zero output gap. He adds in a footnote that money-financed are not inflationary in a growing economy; in that case, for price stability “the high-powered money stock must grow at the rate of growth.” Then when he writes down a model, this has become the condition that government budget must be balanced, which is something different again. Also, I must say I can’t help wrinkling my nose a little, when I read about the “stock of high-powered money,” at the smell of a musty antique.

EDIT: Thanks to Daniele Santolamazza for correcting me on the origins of the ELR proposal.

Functional Finance and Sound Finance


Anyone who who has been following debates on fiscal policy over the past few years will have noticed that, among those who think fiscal policy can be effective, there are two distinct camps. There is a minority who think that fiscal policy is not subject to a budget constraint; that is, that as long as a government borrows in its own currency, its existing liabilities never limit its ability to adjust taxes and spending to bring the economy to full employment. And there are the majority who think that governments are subject to a binding budget constraint; that is, that while adjusting spending and taxes can in principle be used to bring about full employment, it may be impossible or undesirable to do so when the level of government debt is already high. In this view, maintaining full employment should be left to monetary policy. Following Abba Lerner, I call the first position “functional finance” and the second position “sound finance.”

I believe there are important differences between these two positions. But I also believe that these differences have not been clearly articulated, and as a result these debates between them been unproductive. It is my view that there are no important differences in terms of economic theory between the two positions. A perfect application of a functional finance policy rule and of a sound finance policy rule are indistinguishable. The difference between the camps is with respect to policy errors — which errors are most likely, and which are most costly.

Alternative Policy Rules

The starting point is the idea of instruments, which are variables directly controlled by the policymaker; and targets, which are the variables the policymaker wants to set at some level but cannot control directly. When the target variable is not at its desired level, the policymaker adjusts one or more instruments to try to bring it there. This creates relationship between the current level of the target and the chosen level of the instrument. We call this relationship a policy rule. Both functional finance and sound finance represent policy rules in this sense. Tinbergen’s Rule says that for policy rules to be successful (in the sense that all targets converge to their desired levels), there must be at least as many instruments as targets. One policy lever cannot be relied on to achieve two separate outcomes.

We have two instruments in macroeconomic policy: the government budget balance, and the central bank-controlled interest rate. What are our targets?

At first glance, full employment and price stability appear to be two separate targets. But in fact, both Lerner’s functional finance and the sound finance of modern textbooks agree that inflation is the result of demand-determined expenditure departing from a technologically determined level of potential output. Less than full employment means falling inflation, or deflation; overfull employment means high or rising inflation. So full employment and price stability are not two separate targets, they are two ways of describing the same target.

Both camps agree that we can identify a unique target level of output, and they agree on what that target should be. They also agree that output rises with higher government deficits, and falls with higher interest rates. So when interest rates are too high, or budget deficits too small, we will see unemployment (and perhaps deflation); when interest rates are too low or deficits are too large, we will see inflation (and perhaps bottlenecks and rising relative prices of factors in inelastic supply).

This consensus is shown in Figure 1. The full employment locus shows all the combinations of interest rates and fiscal balances that are compatible with full employment and price stability. A fall in private demand will require a rise in the deficit and/or a fall in interest rates to maintain full employment, so it will shift the full employment locus down and to the left. Similarly, a rise in private demand will shift the locus up and to the right. But for any level of private demand, with two instruments and only one target, there are an infinite number of combinations that achieve full employment.

(It is convenient to think of the fiscal balance on the horizontal axis as the primary balance, that is, the balance net of interest payments. So we are implicitly assuming that interest payments do not raise aggregate demand. It is also convenient to think of the interest rate as the real rate, that is, net of inflation. It would be straightforward to incorporate the effects of interest payments and inflation into the story, but would not change it in any interesting way.)

The first point of disagreement is what to do at a point like a. Output is below potential, but which instrument should be used to raise it? Functional finance says, the fiscal balance: government spending should be raised (or taxes should be lowered), moving the economy to the left, until we reach the full employment locus. The modern sound-finance consensus says that the interest rate should be lowered, moving the economy downward to the full employment locus. Both agree that government should do something to raise output. The disagreement is over which instrument to use.

Whichever instrument is used to keep output at potential, there is one instrument left over for some other target. The logical candidate is the sustainability of government debt.

We’ve discussed the math of government debt dynamics quite a bit on this blog. (See here and here and here and here.) The important thing for our purposes is that the long-run trajectory of the debt-GDP ratio depends on the primary balance, the interest rate on government borrowing, and the growth rate of GDP. If we write the ratio of government debt to GDP as b, and the primary deficit as a share of GDP as d, then for a given deficit, the equilibrium condition is b=d* 1/(g-r), where g is the average or expected growth rate of GDP over the period of interest. So for a given debt-GDP ratio b, the primary deficit required to hold it constant is d = b(g-r). (This is all just accounting; it does not depend on any economic assumptions.) It’s evident that, if we take the growth rate as exogenous, then for any given debt-GDP ratio there is a set of r, d combinations for which the debt-GDP ratio is constant. We can represent these values graphically in Figure 2. The dotted horizontal line is the growth rate. The diagonal line is the constant debt ratio locus. With a deficit or interest rate above the diagonal line, the debt-GDP ratio will rise; below, it will fall.

Note that the slope of the diagonal depends on the starting debt-GDP ratio — the higher it is, the shallower the slope will be. With no government debt, the line is vertical at the primary balance = 0 axis. So in any period in which the economy is at a point above the debt-sustainability locus, the diagonal rotates clockwise; in any period in which the economy is below the debt-sustainability locus, the diagonal rotates counter-clockwise.

What happens if the economy is off the constant-debt locus? It depends. In the area marked A (everything above the heavy line), the debt-GDP ratio rises without limit. In B, the debt-GDP ratio rises but converges to a finite value. In C the ratio falls to a finite value. In D, the debt-GDP ratio falls to zero and the government then accumulates a positive asset position, which eventually converges to a finite fraction of GDP. Finally, in area E the debt-GDP ratio falls to zero and the government then accumulates a positive asset position that rises without limit as a share of GDP. (If you are unconvinced we can go through the math.) Since the government budget constraint is normally taken to be the condition that debt-GDP ratio not rise without limit, we can ignore the distinctions between cases B through E and regard the heavy line as the government budget constraint.

We then combine this constraint with the full employment locus to give Figure 3.

Now we have two instruments and two targets. Or rather, one and a half targets: Since there is nothing special about the current debt-GDP ratio, we don’t need it to stay constant; we just need it not to go to infinity. So we don’t need to be on the debt-sustainability curve, we need to be on or below it. Point b, which satisfies the budget constraint exactly, is fine, but so is anywhere on the full employment locus below and to the right of b.

The functional finance-sound finance divide is just this: Functional finance says the fiscal balance instrument should be assigned to the full employment target and the interest rate instrument should be assigned to the debt sustainability target. Sound finance says the interest rate instrument should be assigned to the full employment target and and the fiscal balance instrument should be assigned to the debt sustainability target.

Functional finance and sound finance agree that the economy should be at a point like b. If policy were executed perfectly, the economy would always be at such a point, and there would be no way of knowing which rule was being followed. Since both target should always be at their chosen levels, it would make no difference — and be impossible to tell — which instrument was assigned to which target. The difference between the positions only becomes apparent when policy is not executed perfectly, and the economy departs from a position of full employment with sustainable public debt.

Consider a point somewhere above b, where we are have high unemployment but the debt-GDP ratio is rising without limit. What to do? Both orthodoxy and Lernerism want to get the economy back to a point like b, but they disagree on how.

In the sound-finance view, the interest rate instrument is committed to the output target. This means we must use the fiscal balance instrument free to meet the debt sustainability condition. This is how policy is normally discussed: An unsustainable upward trajectory in the debt position requires the government balance to move  toward surplus. In this case, that means that the government must cut spending or raise taxes, despite the fact that demand is already too low. Under Lernerian functional finance, on the other hand, the fiscal balance is committed to the output target, so the rule calls for higher deficits even though the debt position is already unsustainable. It is then the responsibility of monetary policy to adjust to maintain debt sustainability.

These alternatives are shown in Figure 4. The right-hand trajectory from c to b is the orthodox path. The left-hand trajectory is the Lernerian path. Implicit in the orthodox path is the idea that deficits must be brought down first, meaning a substantial period of high unemployment and output below potential; only once debt is on a sustainable path can interest rates be reduced to move back toward full employment. While the Lernerian path says in effect: If government debt is rising out of control, the central bank should intervene to force interest rates down to a level where the debt is sustainable. Then, if the resulting liquidity raises expenditure above the full employment level, you can subsequently raise taxes or cut transfers to bring demand back down.

Orthodoxy says that budget problems must be addressed fiscally. But this is true only on the implicit assumption that the interest rate is not available as an instrument to target debt sustainability. Sound finance’s policy rule is a Taylor-type rule for monetary policy, combined with a long-term government budget position that satisfies the debt-sustainability constraint at that interest rate. Functional finance’s policy rule: (1) fix the interest rate at a level at or below the expected growth rate (maybe even zero); (2) adjust transfers and taxes until output is at the full employment/stable prices level. The claim that fiscal policy must be subject to a budget constraint, comes down to the claim that the central bank cannot or will not keep r sufficiently low to make the full-employment fiscal position sustainable.

Why is there such disagreement about which instrument should be assigned to which target? It seems to me that the most important argument from the sound finance side is that elected governments cannot be trusted with the instrument of discretionary fiscal policy. They will not set taxes and transfers to bring aggregate demand to the full employment level, but will choose a higher, inflationary level of demand. Only independent central banks can be trusted to bring output to its socially optimal level. In this sense, the functional finance-sound finance divide is not a debate about economic theory, but about politics and sociology.

There are also more specifically economic disagreements. The sound finance side is more confident than the functional finance side about how quickly and reliably a change in interest rates will affect output. If there is a long lag between the change in the instrument and its effect, hitting the target requires accurate prediction of the state of the economy farther into the future. The existence of the ZLB reinforces this concern, since it is really just a special case of interest-inelasticity. (The statement “output does not respond strongly to any feasible change in interest rates” is equivalent to the statement “the interest-rate change needed to achieve a strong output response is not feasible.”) The functional finance side also tends to see a greater social cost in falling below full employment than rising above it, while the sound finance side tends to see the costs as symmetrical.

That is the framework. Now consider some modifications and special cases.


A natural objection to the functional finance view is that it may not be possible for the central bank to maintain interest rates low enough to keep debt sustainable. If we live in a world of high capital mobility and our government’s liabilities are close substitutes for liabilities elsewhere in the world, then the private sector will not hold them if their yield is too much lower. In this case — which is not unrealistic for small, open countries — the interest rate ceases to be a policy variable. This is shown in Figure 5, where r* is the exogenous work interest rate.

At a point like d in the figure, the public debt is stable but output is below potential. A move toward a primary deficit would raise output but put the debt on an unsustainable path. This case is not inherently implausible — one would need to think carefully about the concrete assumptions it embodies — but it is important to recognize that it rules out sound finance as well as functional finance. If the interest rate is set exogenously at the world level, it cannot be used to stabilize public debt or to stabilize output. An additional instrument is needed; the exchange rate is the natural choice. Since the exchange rate cannot straightforwardly be used to achieve debt sustainability, in this case there is a natural argument to switch the assignment of fiscal policy to debt sustainability and achieve full employment via the exchange rate.

Another possibility, which has been getting increasing attention recently, is that very low interest rates are destabilizing for the financial system. (I have criticized this idea before, but I don’t think it can be ruled out definitively.) Then we have another condition to satisfy, a asset price stability condition. Like the debt sustainability condition, this is asymmetrical, it doesn’t have to be satisfied exactly. But this one is a floor on interest rates rather than a ceiling. The is shown in Figure 6. Here, the asset price stability constraint does not initially prevent achieving both the other targets: As in Figure 3, point b initially satisfies all the constraints, as does any other point along the full employment locus below and to the right of it, down to the dotted line.

But what if a fall in private demand shifts the full employment locus far to the left? Here there is an important difference between the sound finance and functional finance rules. The functional finance rule says that the fall in private demand requires the government budget to move toward deficit. That is, we move left from b to the new full employment locus. This may in turn require a fall in interest rates, if the higher deficits would otherwise put the public debt on an unsustainable path. But public debt sustainability never requires an interest rate below the long term growth rate. So, since it is not plausible that the minimum interest rate compatible with asset price stability condition is greater than the growth rate, the possibility of asset bubbles should not limit the application of the functional finance rule.

The sound finance rule, on the other hand, says that the response to a fall in private demand should be a reduction in the interest rate. In other words, faced with the fall in private demand shown in the figure, we should move downward from point b  to the new full employment locus. Now there is the possibility that the required interest rate is incompatible with asset price stability. (In some views, this is precisely what happened a decade ago, setting the stage for the housing bubble.) This becomes an argument for setting interest rates higher than the conventional policy rule implies, even at the cost of higher unemployment.

Formally, the ZLB is identical to the asset price stability condition: both set floors to allowable interest rates. It is curious that, while concern with the ZLB and with the destabilizing effects of low interest rates often come from opposite political positions, they are — at least in this framework — equivalent in their implications for policy. Both are arguments for a reliance on fiscal policy to offset fall in private demand in general, rather than waiting for the floor to be reached — that is, for some form of functional finance.

Finally, consider the case where the fiscal balance is exogenously fixed, as shown in Figure 7. I think this is the case most critics of functional finance have in mind. If the budget authority, for whatever reason, is committed to tax and spending policies corresponding to a primary deficit, there may be no interest rate that can deliver both debt sustainability and full employment. The central bank must choose one. If it chooses debt sustainability, we have a situation known in the literature as “fiscal dominance.” The central bank must increase its liabilities as needed to finance the government deficit, even if that results in aggregate demand rising to inflationary levels. This is the situation at point e.

It is important to stress that Figure 7 is not what is advocated by functional finance. There is an understandable but unfortunate confusion between the claim “deficits can be at whatever level is needed to reach full employment” and “deficits can be at whatever level you want.” Functional finance says the former, not the latter. A functional finance rule would call for the government to raise taxes or cut spending at a point like e — not to balance the budget, but to eliminate the inflation. The practical problem for functional finance supporters is to convince skeptics that such a rule will be followed by an elected government.


Advocates of functional finance say that a government that borrows in its own currency never needs to adjust its taxes or spending on account of its current deficit or accumulated debt. The fiscal balance can always be set at whatever level is needed to achieve full employment. Their sound-finance critics reply, “It’s true that a deficit will raise current output. But over the long run you need a primary surplus to ensure that the government stays on its budget constraint. If the central bank is forced to monetize the debt instead, you will have runaway inflation.”

The critics are correctly describing the situation in Figure 7, where it is true that the government budget position has been set without regard for debt sustainability, the central bank is monetizing the debt (this is simply another way of describing holding interest rates low enough to maintain a stable path for government liabilities), and there is uncontrolled inflation. But the inference the critics draw from this possibility — that fiscal policy must target debt sustainability — is not correct. The correct inference is that at least one of the two instruments must target debt sustainability, and at least one must target full employment. The problem in Figure 7 is that budget balance is being set without regard for either condition — that is, it is in violation of both policy rules. Either the sound finance rule, or the functional finance rule, or any linear combination of the two, would ensure that the economy does not remain at a point like e but instead converges to one like b in Figure 3.

The debate between sound finance and functional finance cannot be resolved as long as they are framed in terms of what kind of rule is feasible in principle, and what outcome results when it is followed exactly. The disagreement is about what kinds of rules policymakers can be expected to adhere to in practice, and about the relative costs of different policy errors.

[This post was inspired by this talk by Brad DeLong, and by some comments by Nick Rowe which I cannot locate now.]

Borrowing ≠ Debt

There’s a common shorthand that makes “debt” and “borrowing” interchangeable. The question of why an economic unit had rising debt over some period, is treated as equivalent to the question of why it was borrowing more over that period, or why its expenditure was higher relative to its income. This is a natural way of talking, but it isn’t really correct.

The point of Arjun’s and my paper on debt dynamics was to show that for household debt, borrowing and changes in debt don’t line up well at all. While some periods of rising household leverage — like the housing bubble of the 2000s — were also periods of high household borrowing, only a small part of longer-term changes in household debt can be explained this way. This is because interest, income growth and inflation rates also affect debt-income ratios, and movements in these other variables often swamp any change in household borrowing.
As far as I know, we were the first people to make this argument in a systematic way for household debt. For government debt, it’s a bit better known — but only a bit. People like Willem Buiter or Jamie Galbraith do point out that the fall in US debt after World War II had much more to do with growth and inflation than with large primary surpluses. You can find the argument more fully developed for the US in papers by Hall and Sargent  or Aizenman and Marion, and for a large sample of countries by Abbas et al., which I’ve discussed here before. But while many of the people making it are hardly marginal, the point that government borrowing and government debt are not equivalent, or even always closely linked, hasn’t really made it into the larger conversation. It’s still common to find even very smart people saying things like this:

We didn’t have anything you could call a deficit problem until 1980. We then saw rising debt under Reagan-Bush; falling debt under Clinton; rising under Bush II; and a sharp rise in the aftermath of the financial crisis. This is not a bipartisan problem of runaway deficits! 

Note how the terms “deficits” and “rising debt” are used interchangeably; and though the text mostly says deficits, the chart next to this passage shows the ratio of debt to GDP.
What we have here is a kind of morality tale where responsible policy — keeping government spending in line with revenues — is rewarded with falling debt; while irresponsible policy — deficits! — gets its just desserts in the form of rising debt ratios. It’s a seductive story, in part because it does have an element of truth. But it’s mostly false, and misleading. More precisely, it’s about one quarter true and three quarters false.
Here’s the same graph of federal debt since World War II, showing the annual change in debt ratio (red bars) and the primary deficit (black bars), both measured as a fraction of GDP. (The primary deficit is the difference between spending other than interest payments and revenue; it’s the standard measure of the difference between current expenditure and current revenue.) So what do we see?
It is true that the federal government mostly ran primary surpluses from the end of the war until 1980, and more generally, that periods of surpluses were mostly periods of rising debt, and conversely. So it might seem that using “deficits” and “rising debt” interchangeably, while not strictly correct, doesn’t distort the picture in any major way. But it does! Look more carefully at the 1970s and 1980s — the black bars look very similar, don’t they? In fact, deficits under Reagan were hardy larger than under Ford and Carter —  a cumulative 6.2 percent of GDP over 1982-1986, compared with 5.6 percent of GDP over 1975-1978. Yet the debt-GDP ratio rose by just a single point (from 24 to 25) in the first episode, but by 8 points (from 32 to 40) in the second. Why did debt increase in the 1980s but not in the 1970s? Because in the 1980s the interest rate on federal debt was well above the economy’s growth rate, while in the 1970s, it was well below it. In that precise sense, if debt is a problem it very much is a bipartisan one; Volcker was the appointee of both Carter and Reagan.
Here’s the same data by decades, and for the pre- and post-1980 periods and some politically salient subperiods.  The third column shows the part of debt changes not explained by the primary balance. This corresponds to what Arjun and I call “Fisher dynamics” — the contribution of growth, inflation and interest rates to changes in leverage. [*] The units are percent of GDP.
Totals by Decade
Primary Deficit Change in Debt Residual Debt Change
1950s -8.6 -29.6 -20.9
1960s -7.3 -17.7 -10.4
1970s 2.8 -1.7 -4.6
1980s 3.3 16.0 12.7
1990s -15.9 -7.3 8.6
2000s 23.7 27.9 4.2
Annual averages
Primary Deficit Change in Debt Residual Debt Change
1947-1980 -0.7 -2.0 -1.2
1981-2011 0.1 1.3 1.2
   1981-1992 0.3 1.8 1.5
   1993-2000 -2.7 -1.6 1.1
   2001-2008 -0.1 0.8 0.9
   2009-2011 7.3 8.9 1.6

Here again, we see that while the growth of debt looks very different between the 1970s and 1980s, the behavior of deficits does not. Despite Reagan’s tax cuts and military buildup, the overall relationship between government revenues and expenditures was essentially the same in the two decades. Practically all of the acceleration in debt growth in the 1980s compared with the 1970s is due to higher interest rates and lower inflation.

Over the longer run, it is true that there is a shift from primary surpluses before 1980 to primary deficits afterward. (This is different from our finding for households, where borrowing actually fell after 1980.) But the change in fiscal balances is less than 25 percent the change in debt growth. In other words, the shift toward deficit spending, while real, only accounts for a quarter of the change in the trajectory of the federal debt. This is why I said above that the morality-tale version of the rising debt story is a quarter right and three quarters wrong.

By the way, this is strikingly consistent with the results of the big IMF study on the evolution of government debt ratios around the world. Looking at 60 episodes of large increases in debt-GDP ratios over the 20th century, they find that only about a third of the average increase is accounted for by primary deficits. [2] For episodes of falling debt, the role of primary surpluses is somewhat larger, especially in Europe, but if we focus on the postwar decades specifically then, again, primary surpluses accounted for only a about a third of the average fall. So while the link between government debt and deficits has been a bit weaker in the US than elsewhere, it’s quite weak in general.

So. Why should we care?

Most obviously, you should care if you’re worried about government debt. Now maybe you shouldn’t worry. But if you do think debt is a problem, then you are looking in the wrong place if you think holding down government borrowing is the solution. What matters is holding down i – (g + π) — that is, keeping interest rates low relative to growth and inflation. And while higher growth may not be within reach of policy, higher inflation and lower interest rates certainly are.

Even if you insist on worrying not just about government debt but about government borrowing, it’s important to note that the cumulative deficits of 2009-2011, at 22 percent of GDP, were exactly equal to the cumulative surpluses over the Clinton years, and only slightly smaller than the cumulative primary surpluses over the whole period 1947-1979. So if for whatever reason you want to keep borrowing down, policies to avoid deep recessions are more important than policies to control spending and raise revenue.

More broadly, I keep harping on this because I think the assumption that the path of government debt is the result of government borrowing choices, is symptomatic of a larger failure to think clearly about this stuff. Most practically, the idea that the long-run “sustainability” of the  debt requires efforts to control government borrowing — an idea which goes unquestioned even at the far liberal-Keynesian end of the policy spectrum —  is a serious fetter on proposals for more stimulus in the short run, and is a convenient justification for all sorts of appalling ideas. And in general, I just reject the whole idea of responsibility. It’s ideology in the strict sense — treating the conditions of existence of the dominant class as if they were natural law. Keynes was right to see this tendency to view of all of life through a financial lens — to see saving and accumulating as the highest goals in life, to think we should forego real goods to improve our financial position — as “one of those semicriminal, semi-pathological propensities which one hands over with a shudder to the specialists in mental disease.”

On a methodological level, I see reframing the question of the evolution of debt in terms of the independent contributions of primary deficits, growth, inflation and interest rates as part of a larger effort to think about the economy in historical, dynamic terms, rather than in terms of equilibrium. But we’ll save that thought for another time.

The important point is that, historically, changes in government borrowing have not been the main factor in the evolution of debt-GDP ratios. Acknowledging that fact should be the price of admission to any serious discussion of fiscal policy.

[1] Strictly speaking, debt ratios can change for reasons other than either the primary balance or Fisher dynamics, such as defaults or the effects of exchange rate movements on foreign-currency-denominated debt. But none of these apply to the postwar US.

[2] The picture is a bit different from the US, since adverse exchange-rate movements are quite important in many of these episodes. But it remains true that high deficits are the main factor in only a minority of large increases in debt-GDP ratios.

Did We Have a Crisis Because Deficits Were Too Small?

In comments to the previous post on fiscal policy, Steve Roth points to a couple posts from his own (excellent) blog pointing to a similar argument by Randy Wray, that falling federal debt-GDP ratios nominal volumes of government debt have consistently preceded financial crises historically.

Also in comments, Chris Mealy asks,

Isn’t the idea that sufficient government debts will prevent phony safe assets and the financial crises they lead to?

Right, exactly!
A couple years ago, VoxEU ran several good pieces making exactly this argument — that it was the lack of sufficient government debt that spurred the growth of mortgage securitization. Here is one:

The increased demand for US government debt by emerging economy central banks led to lower yields, thus forcing those savers in the OECD countries who would normally have held government assets to frantically “search for returns”. … The AAA tranches on securitised US mortgages … seemed to provide the safety plus a “yield pick up” without any risk… 

The key technology that permitted the transformation of US mortgages into safe liquid assets was securitisation. … The massive buying of US government paper by emerging market central banks had displaced other investors whose preference previously had been for safe, short-term, liquid assets.  … The excess demand for short-term, safe, liquid assets created by emerging economies’ accumulation of reserves could not have been satisfied by the securitisation of US mortgages (and consumer credit) without massive credit and liquidity “enhancements” by the banking system. … 

Looking forward, this analysis implies that the current (smaller but still sizeable) US current account deficit should not lead to similar asset supply and demand mismatches since US households are now starting to save and it is the US government which is running the deficit, thus supplying exactly the kind of assets needed

And here is another, from an impeccably mainstream author:

The entire world had an insatiable demand for safe debt instruments – including foreign central banks and investors, but also many US financial institutions. This put enormous pressure on the US financial system… The financial sector was able to create micro-AAA assets from the securitisation of lower quality ones, but at the cost of exposing the system to a panic… In this view, the surge of safe-asset demand was a key factor behind the rise in leverage and macroeconomic risk concentration in financial institutions… These institutions sought the profits generated from bridging the gap between this rise in demand and the expansion of its natural supply. … 

[Once the crisis began], the underlying structural deficit of safe assets worsened as the … triple-A assets from the securitisation industry dried up and the spike in perceived uncertainty further increased demand for these assets. Safe interest rates plummeted to record low levels. … Global imbalances and their feared sudden reversal never played a significant role for the US during this deep crisis. In fact, the worse things became, the more domestic and foreign investors ran to US Treasuries for cover and treasury rates plummeted (and the dollar appreciated). … 

One approach to addressing these issues prospectively would be for governments to explicitly bear a greater share of the systemic risk. … If the governments in asset-producing countries were to do it directly, then they would have to issue bonds beyond their fiscal needs.

The logic is very clear and, to me at least, compelling: For a variety of reasons (including but not limited to reserve accumulation by developing-country central banks) there was an increase in demand for safe, liquid assets, the private supply of which is generally inelastic. The excess demand pushed up the price of the existing stock of safe assets (especially Treasuries), and increased pressure to develop substitutes. (This went beyond the usual pressure to develop new methods of producing any good with a rising price, since a number of financial actors have some minimum yield — i.e. maximum price — of safe assets as a condition of their continued existence.) Mortgage-backed securities were thought to be such substitutes. Once the technology of securitization was developed, you also had a rise in mortgage lending and the supply of MBSs continued growing under its own momentum; but in this story, the original impetus came unequivocally from the demand for substitutes for scarce government debt. It’s very hard to avoid the conclusion that if the US government had only issued more debt in the decade before the crisis, the housing bubble and subsequent crash would have been much milder.
While we’re at it, I can resist reposting the old post where I first mentioned this stuff:
A focus on cyclical stabilization assumes that there is no systematic long-term divergence between aggregate supply and aggregate demand. But Keynes believed that there was a secular tendency toward stagnation in advanced capitalist economies, so that maintaining full employment meant not just using public expenditure to stabilize private investment demand, but to incrementally replace it.
Another way of looking at this is that the steady shift from small-scale to industrial production implies a growing weight of illiquid assets in the form of fixed capital. There is not, however, any corresponding long-term increase in the demand for illiquid liabilities. If anything, the sociological patterns of capitalism point the other way, as industrial dynasties whose social existence was linked to particular enterprises have been steadily replaced by rentiers. The whole line of financial innovations from the first joint-stock companies to the recent securitization boom have been attempts to bridge this gap. But this requires ever-deepening financialization, with all the social waste and instability that implies.
It’s the government’s ability to issue liabilities backed by the whole economic output that makes it uniquely able to satisfy the demands of wealth-holders for liquid assets. In the functional finance tradition going back to Lerner, modern states do not possess a budget constraint in the same way households or firms do. Public borrowing has nothing to do with “funding” spending, it’s all about how much government debt the authorities want the banking system to hold. If the demand for safe, liquid assets rises secularly over time, so should government borrowing.
From this point of view, one important source of the recent financial crisis was the surpluses of the 1990s, and insufficient borrowing by the US government in general. By restricting the supply of Treasuries, this excessive fiscal restraint spurred the creation of private sector substitutes purporting to offer similar liquidity properties, in the form of various asset-backed securities. But these new financial assets remained at bottom claims on specific illiquid real assets and their liquidity remained vulnerable to shifts in (expectations of) the value of those assets.
The response to the crisis in 2008 then consists of the Fed retroactively correcting the undersupply of government liabilities by engaging in a wholesale swap of public for private liabilities, leaving banks (and liquidity-demanding wealth owners) holding government liabilities instead of private financial assets. The increase in public debt wasn’t an unfortunate side-effect of the solution to the financial crisis, it was the solution.
Along the same lines, I sometimes wonder how much the huge proportion of government debt on bank balance sheets — 75 percent of assets in 1945 vs. 1.5 percent in 2005 — contributed to the financial stability of the immediate postwar era. With that many safe assets sloshing around, it didn’t take financial engineering or speculative bubbles to convince banks to hold claims on fixed capital and housing. But as the supply of government debt has dwindled the inducements to hold other assets have had to grow increasingly garish.
From which I conclude that ever-increasing government deficits may in fact be better Keynesianism – theoretically, historically and pragmatically – than countercyclical demand management.
(What’s striking to me, rereading this now, is that when I wrote it I had not read any Leijonhufvud. Yet the argument that capitalism suffers from a chronic oversupply of long, illiquid assets is one of the central messages of Keynesian Economics and the Economics of Keynes — “no mortal being can hold land to maturity,” etc. I got the idea from Minsky, I suppose, or maybe from Michael Perelman, who are both very clear that the specific institutions of capitalism are in many ways in deep tension with the development of long-lived capital goods.)

UPDATE: Hey look, The Economist agrees. I think that means it’s time to move on.

UPDATE 2: So does Joe Weisenthal at the The Business Insider. His argument (and Stephanie Kelton’s) is different from the one here — it focuses on the fact that net savings across sectors have to sum to zero, as opposed to the government’s advantage in providing liquidity. But the fundamental point is the same, that the important thing about the government fiscal position is the implications it has for private balance sheets.

UPDATE 3: Steve R. points out that I misread his posts — Wray’s argument is about the nominal volume of federal debt outstanding, not the debt-GDP ratio. Hmm. I’m not sure I buy that relationship as evidence of anything … but it’s still good to see that Wray is asking this question. Steve also points to this paper, which looks very interesting.

Prolegomena to Any Future Post on Fiscal Policy

Hyman Minsky famously asked, Can “it” happen again? No, he answered, it can’t: A deep depression on the scale of the 1930s is not possible in the post-World War II US. One reason why not:

There is a large outstanding government debt… This both sets a floor to liquidity and weakens the link between the money supply and business borrowing.

In other words, a large government debt is stabilizing, because it means that the supply of liquidity — assets that can serve as, and can readily be converted into, means of payment — depends less on the state of the financial system. 
Let’s take a step back. Any unit in a capitalist economy incurs various money obligations, and receives various streams of money payments. [1] If a unit cannot meet its contracted payments in any period, it must default, with whatever legal consequences that entails. To avoid this, economic units, especially banks, must manage both market liquidity (the ability to convert assets in their portfolio into means of payment) and funding liquidity (the ability to issue new liabilities.) In general, when a bank expands its balance sheet, it becomes less liquid — that is, it increases the number of possible future states of the world in which it is unable to acquire the means of payment to meet its current obligations. This is why interest rates tend to rise in response to increased private borrowing. 
Or rather, a bank that expands its balance sheet in order to acquire private debt becomes less liquid, or is likely to find itself less liquid in a crisis. A bank that acquires public debt, on the other hand, becomes more liquid. This is why banks hold government liabilities as reserves, beyond any statutory requirements. Government bonds are, in Minsky’s words, “ultimate liquidity” — the only assets that can always be converted to means of payment as needed. This is why interest rates do not rise in response to public borrowing, even when government deficits are very large. [2]

DR is the federal deficit as a percent of GDP. It’s the one that goes way up during the war. CPR and RRBR are the two main private interest rate indices for the period. They’re the ones that don’t.
This all respectable mainstream economic theory. But I don’t think the Minskyan implications are really acknowledged in mainstream policy discussions. Do we agree that one of the main reasons that a crisis on the scale of 1929-1933 was impossible postwar was the “floor to liquidity” provided by banks’ holdings of federal debt? Then perhaps we shouldn’t be surprised that a crisis of that scale almost did occur in 2007, when the share of federal debt in financial-system assets had fallen to less than 5 percent, compared with 15 percent when Minsky wrote those lines.
Indeed, much of the Fed’s response to the crisis was various policies to raise this ratio; and one danger of deficit reduction is that the banking system still needs more government bonds. Or as Brad DeLong says:

When the world is short of safe assets–and investors are desperate to hold them–to complain about budget deficits in rock-solid reserve-currency countries and thus about safe asset issuance is profoundly stupid.

Right on; Delong has read his Minsky.

Now, Brad, will you take the next step with me and Hyman? Can we also agree that even when there isn’t a shortage of safe assets today, it’s good to keep a stock on hand, just in case? Can we agree that if there’s a chance that in the next decade the world economy will fly apart due to a lack of safe assets, then it’s a bit foolhardy to deliberately reduce the supply of them? Can we agree that, in retrospect, those big Clinton surpluses were — well, I won’t say profoundly stupid, but maybe not the best idea?

And then we can agree that whenever anyone talks about “tackling our long-term government debt problem,” what they really mean is “making future financial crises more likely.”

EDIT: Obviously, this sounds a lot like Modern Monetary Theory. But while I agree substantively with MMT, I think it’s better to think of government liabilities being special because they increase the net liquidity of the financial system, rather than because they can be used to satisfy tax obligations.

There’s one other analytic issue, which I haven’t seen dealt with satisfactorily. Government deficits operate through two channels: They increase the flow of demand for currently-produced goods and services, and they increase the stock of government debt in private hands. Now, under certain assumptions, you might say these are just two ways of describing the same phenomenon. If you think of the economy as a market with two goods, current output and bonds, then increasing the demand for one and increasing the supply of the other are logically equivalent. But this is not the only way of thinking of the economy. (Among other things, while markets certainly exist as social phenomena, describing the economy as a whole as a market is only a metaphor — one that may be more or less illuminating depending on the questions we are interested in.) In general, the two channels are going to have two distinct effects, and it would be nice to be able to think them through separately. But almost everyone, across the whole spectrum, tends to collapse them into one.

[1] One reason I like David Graeber is that he understands that this is a better starting point for economic analysis than the exchange of goods.
[2] Obviously this claim applies only to the United States and similar countries. I am going to leave aside for now what “similar” means.

A History of Debt/GDP

“Probably more uninformed statements have been made on public-sector debt and deficits,” says Willem Buiter, “than on any other subject in macroeconomics. Proof by repeated assertion has frequently appeared to be an acceptable substitute for proof by deduction or proof by induction.”

It’s hard to disagree. 
But at least we know where an informed discussion starts. It starts from the least controversial equation of macroeconomics, the law of motion of public debt:
b is the ratio of public debt to GDP, d is the ratio of primary deficit to GDP, i is the nominal interest rate, g is the real growth rate of GDP, and pi is inflation. In principle this is true by definition. (In practice things aren’t alway so simple.) The first thing you realize, looking at this equation, is that contrary to the slack-jawed bleating of conventional opinion, there’s no necessary connection between the evolution of public debt and government spending and taxes. Interest rates, growth rates and inflation are, in principle, just as important as the primary balance. Which naturally invites the question, which have been more important in practice?
There have been various efforts to answer this question for different countries in different periods, but until recently there wasn’t any systematic effort to answer it for a broad sample of countries over a long period. I was thinking of trying to do such an exercise myself. But it looks like that’s not necessary. As Tom M. points out in comments,  the IMF has just undertaken such an exercise. Using the new Historical Public Debt Database, they’ve decomposed the debt-GDP ratios of 174 countries, from 1880 to the present, into the four components of the law of motion. (Plus a fifth, discussed below.) It’s an impressive project. Ands far as one can tell from this brief presentation, they did it right. Admittedly it’s a laconic 25-page powerpoint, but there’s not even the hint of a suggestion that microfoundations or welfare analysis would contribute anything. The question is just, how much has each of the components contributed to shifts in debt-GDP ratios historically?
As I’ve noted here before, the critical issue is the relationship between g and i, or (g + pi) and i as I’ve written it here. On this point, the IMF study gives ammunition to both sides.
From roughly 1895 to 1920, and from 1935 to 1980, nominal growth rates (g + pi) generally exceeded nominal interest rates. From 1880 to 1895, from 1920 to 1935, and from 1980 to the present, interest mostly exceeded growth. It’s impossible, looking at this picture, to say one relationship or the other is normal. Lernerian-Keynesians will say, why can’t the conditions of the postwar decades be reproduced by any government that chooses to; while the orthodox (Marxists and neoclassicals equally) will say the postwar decades were anomalous for various reasons — financial repression, limited international mobility of capital, exceptionally strong growth. The historical evidence doesn’t clearly resolve the question either way.

Given the unstable relationship between g and i, it’s not surprising there’s no consistent pattern in episodes of long-term reduction in debt-GDP ratios. I had hoped such episodes would turn out to be always, or almost always, the result of faster growth, lower interest rates, and higher inflation. This is basically true for the postwar decades, when the biggest debt reductions happened. Since 1980, though, it seems that countries that have reduced their debt-GDP ratios have done it the hard way, by taxing more than they spent. Over the whole period since 1880, periods of major (at least 10 percent of GDP) debt reduction has involved primary surpluses and g > r in about equal measure.

Another interesting point is how much the law of motion turns out to have exceptions. The IMF’s version of the equation above includes an additional term on the right side: SFA, or stock-flow adjustment, meaning the discrepancy between the flow of debt implied by the other terms of the equation and the stock of debt actually observed. This discrepancy turns out to be often quite large. This could reflect a lot of factors; but for recent episodes of rising debt-GDP ratios (in which SFA seems to play a central role) the obvious interpretation is that it reflects the assumption by the government of the banking system’s debts, which is often not reflected in official deficit statistics but may be large relative to the stock of debt. The extreme case is Ireland, where the government guarantee of the financial system resulted in the government assuming bank liabilities equal to 45 percent of GDP. To the extent this is an important factor in rising public debt generally — and again, the IMF study supports it — it suggests another reason why concern with balancing the long-term budget by “reforming” Medicare, etc., is misplaced. One financial crisis can cancel out decades of fiscal rectitude; so if you’re concerned about what the debt-GDP ratio will be in 2075, you should spend less time thinking about public spending and taxes, and much more time thinking about effective regulation of the financial sector.
The bottom line is, the dynamics of public debt are complicated. But as always, intractable theoretical controversies become more manageable, or at least more meaningful, when they’re posed as concrete historical questions. Good on the IMF for doing this.

We Are All Austerians Now

Mark Thoma:

we must cut spending and raise taxes to get the debt under control

I’m sorry, but This. Is. Not. True.

If you look at future debt-GDP ratios and think they are too high, how can you reduce them?

1. You can improve the primary balance by raising taxes and/or reducing spending.

2. You can raise the growth rate.

3. You can lower the real interest rate on government debt.

4. You can raise inflation. (This may also help with 3, depending what we think of Fisher’s law.)

EDIT: 5. You can default. (Thanks, Bruce Wilder.)

One is not the only choice. We can, of course, debate which of these choices offers the best tradeoff between feasibility and desirability. But it is not true that reducing the long-run debt-GDP ratio necessarily involves reducing spending or raising taxes. And anyone who want a rational discussion of fiscal issues, needs to stop lying to people that it is.

How bad things are, can be seen by the fact that someone as smart as Barkely Rosser has been convinced that a reluctance to raise taxes is the problem for aggregate demand. When the debate comes down or whether we should raise taxes or cut spending, the real question has been answered, and answered wrong. At that point it’s just a question of what flavor of austerity we want. Thank god at least there’s still Daniel Davis.

If we wanted to move this debate forward, the next step would be to look at periods when the long term debt-GDP ratio was reduced in rich countries. How much was due to the primary balance that Thoma takes for granted is the only solution, how much was due to faster growth, how much to lower interst rates and how much to higher inflation?

It’s Not About the Deficits

I was going to write something about tonight’s debt-celing deal. “Reduces Domestic Discretionary Spending to the Lowest Level Since Eisenhower,” says the White House in triumphant title case. Yay! No more EPA, no more civil rights enforcement, no more federal spending on housing or child care or clean energy. They didn’t need them in the Eisenhower era, so why should we?

It makes me mad. And it’s not good to write when you’re mad. As the man says,

Hatred, even of baseness,
Distorts the features.
Anger, even against injustice,
Makes the voice grow hoarse.

So instead of this appalling deal, let’s talk about the trajectory of the debt historically. Specifically, this very interesting take from the always-interesting Willem Buiter:

The last time the US sovereign radically lowered the ratio of public debt to GDP was between 1946 (the all-time high for the Federal debt burden at 121.20 percent) and 1974 (its post-World War II low at 31.67 percent). Arithmetically, of the 89.53 percentage points reduction in the Federal debt burden, inflation accounted for 52.63pp and real GDP growth accounted for 55.86 pp. Federal surpluses accounted for minus 20.51pp.

Longer average maturity and occasionally sharp bursts of inflation helped erode the real burden of the Federal debt between 1946 and 1974, but so did financial repression – ceilings on nominal interest rates. … Until the Treasury-Federal Reserve Accord of March 1951, the Federal Reserve System was formally committed to maintaining a low interest rate peg on Treasury bonds – a practice introduced in 1942 when the Fed pegged the interest rate on Treasury bills at 0.375 percent. This practice was continued after the war despite a 14 percent rate of CPI inflation in 1947 and an 8 percent rate in 1948. The rate on 3-month Treasury Bills remained at 0.375 percent until June 1947 and did not reach 1.40 percent until March 1951.

Even after the Treasury-Federal Reserve Accord, there remained financial repression in the form of ceilings on bank lending and borrowing rates like Regulation Q, which prohibited the payment of interest on demand deposits. Without financial repression and with a relatively short average debt maturity, it would take high US rates of (unanticipated) inflation to bring down the burden of the debt appreciably.

This is the key point that comes out of the relationships that govern the evolution of the federal debt: Deficits/surpluses are just one factor, along with growth rates, interest rates, and inflation, that determine the trajectory of the debt. There’s no a priori reason to think that long-term shifts in the debt-GDP ratio are more likely to come about through changes in the government’s fiscal stance rather than one of the other three variables; and there’s historical evidence that in practice growth, inflation and interest rates usually matter more. At some point I’ll do an exercise similar to Buiter’s. But in the meantime, I’m happy to take it from him — the dude is the chief economist at Citibank — that, in the the postwar decades, growth and inflation contributed about equally to the very large reduction in the US debt-GDP ratio, while fiscal discipline contributed less than nothing.

So if you wanted to follow the postwar US in reducing the debt-GDP ratio over a long period — it’s not entirely clear why you would want to do this — you should be thinking about faster growth, higher inflation and policies to hold down interest rates (aka “financial repression”), not higher taxes and lower spending. Anyone who says, “The growth of the debt is unsustainable, therefore we need to move the federal budget toward balance” doesn’t know what they’re talking about.

Or, they’re talking about something else.

You can interpret Obama’s relentless pursuit of defeat in the budget-ceiling fight in psychological terms. But it seems more parsimonious to at least consider that he’s simply an honest servant of the country’s owners, who see the crisis as a once-in-a-lifetime chance to roll back the social wage. Raising the Medicare eligibility age wouldn’t have done anything much to reduce the long-term debt-GDP ratio. But it definitely would reduce the number of people with Medicare.

UPDATE: This post is evidently the kind of thing Matt Yglesias has in mind when he says he’s

frustrated by lefties who seem to see the unprecedented Republican obstruction the President is dealing with as part of an 11-dimensional chess game through which Obama “really” wants his progressive initiatives to be frustrated at every term. 

 But this gets the n-dimensional chess metaphor backward, I think. The whole reason people claim Obama is playing a deeper or more complex game is to argue that even when his actions don’t seem to get him closer to his supposed goals, he really is getting there but by some devious route. But if your theory, as here, is that the actual outcome was the intended outcome, you don’t need to assume any deviousness. If I sacrifice my knight for no apparent gain, then maybe I have some complex plan you don’t see — that’s the extra dimensions. But if I’m playing to lose, no extra dimensions are needed to explain my bad move. Yglesias’s frustration here would apply to lefties who argued that Obama’s big progressive victories were really serving a conservative agenda. And there are certainly people who would argue that — if there were any big progressive victories to argue about.

Fiscal Arithmetic: The Blanchard Rule

When we left off, we’d concluded that the relationship between g, the growth rate of GDP, and i, the after-tax interest rate on government debt, was central to the evolution of public debt. When g > i, any primary deficit is sustainable, in the sense that the debt-GDP ratio converges to a finite value; when i > g, no primary deficit is sustainable, and a primary surplus, while formally sustainable at a certain exact value, occupies a knife-edge. Which invites the natural question, so which is bigger, usually?

There are articles that discuss this (tho not as many as you might think). Here’s a good recent article by Jamie Galbraith; I also like this one by Tony Aspromourgos, and “The Intertemporal Budget Constraint and the Sustainability of Budget Deficits” by Arestis and Sawyer. (I’m sorry, I can’t find a version of it online). An earlier and more mainstream, but for our current purposes especially interesting, take is this piece by Olivier Blanchard.  Blanchard says:

If i g were negative, the government would no longer need to generate primary surpluses to achieve sustainability. … The government could even run permanent primary deficits of any size, and these would eventually lead to a positive but constant level of debt… Theory suggests that this case, which corresponds to what is known as ‘dynamic inefficiency’, cannot be excluded, and that in such a case, a government should, on welfare grounds, probably issue more debt until the pressure on interest rates made them at least equal to the growth rate.

So much depends on whether the growth rate exceeds the interest rate, or not. Well, so, does it?

The funny thing about this passage in context is that Blanchard acknowledges that over most of the postwar period, the growth rate has exceeded the interest rate. But, he says, the professional consensus is that interest rates ought to equal or exceed growth rates, so he’ll stick with that assumption for the rest of the article. (There’s almost a genre of economics articles that freely admit a key assumption doesn’t seem to be consistently satisfied in practice, but then blithely go on assuming it. The Marshall-Lerner-Robinson condition is a favorite in this vein.) But we’re not here to mock; we’re here to call the Blanchard rule, the prescription that if i < g, the federal deficit ought to be higher.

Below are graphs of the growth rate and after-tax 10-year government bond rate for 10 OECD countries. Both are deflated by the CPI; the tax rate is the ratio of central government taxes to GDP. This is probably a bit high, but on the other hand the average maturity of government debt is less than 10 years in many OECD countries — in the US it is currently around 4.7 years — so these two biases might more or less cancel each other out, leaving the red line close to the economically relevant interest rate. Source is the OECD statistics site. I’ve excluded 2008-2010 since the Great Recession pulls growth rates sharply down in a (let’s hope!) misleading way. The lighter black line is the growth trend.

Click them to make them bigger!

Clearly we can’t exclude the relevance of the Blanchard rule; for much of the time, for many rich countries, the growth rate of GDP has exceeded the 10-year interest rate. At other times, interest has exceeded growth. What we see in most cases is a fairly stable growth rate, combined with an interest rate that jumps sharply up around 1980 and then drifts downward from somewhere in the 1990s. At some point soon, I hope, I’ll produce decompositions of the change in the fiscal position into the interest rate, the growth rate, changes in taxes and expenditure induced by the growth rate, and autonomous changes in taxes and spending. I suspect the first will be the most important, and the last the least. But in the meantime, we can say just looking at these graphs that changing interest rates are an important component of fiscal dynamics, so it’s wrong to think just in terms of the primary balance.

Which suggests — coming back to the earlier debate with John Quiggin — that if we are concerned with the long-term fiscal position, we should spend at least as much time worrying about policies that affect the interest rate on government debt relative to the growth rate, as we should about taxes relative to expenditures. And we should not assume a priori that a primary deficit is unsustainable.