Tag: macroeconomics

What’s Going On With Inventories?

One of the weirdly under-discussed features of the current macroeconomic situation is the huge role of inventories in the recovery. I read a lot of economics blogs — there are a lot more I don’t read — and at least sporadically the business press, and I’ve hardly seen this discussed at all. But check it out:


The orange line is the change in GDP, the blue line is the contribution of inventory changes. (Sorry it’s fuzzy. I’m technologically hopeless.) Since the end of the recession, 62 percent of GDP growth has been accounted for by inventories. Inventories have accounted for the majority of GDP growth in four of the five post-recession quarters; in the fifth, they were 48 percent. There’s really no precedent for this. It’s not unusual for inventories to be the main source of growth in one post-recession quarter, but never in the past 50 years have they accounted for half of GDP growth for two quarters in a row, let alone for five. [1]

The question then is, what’s it mean. Honestly? I don’t know.

The natural theory is that it’s supply chain risk and credit risk. When you’re not confident you’re regular suppliers will still be in business a few months from now, you want to keep a stash of whatever inputs you depend on them for on hand. And as transactions move toward a cash-on-the-barrelhead basis, everyone has to hold more goods in stock (along with more cash, but that’s happening too.)

But I suspect there are better answers, if one understood the concrete realities underlying the BEA statistics. Any of you hypothetical readers have ideas?

[1] The first post-war recovery in 1947-48 saw inventories play a similarly large role. I doubt the reasons were the same.

Are Microfoundations Necessary?

A typically thoughtful piece by Cosma Shalizi, says Arjun.

And it is thoughtful, for sure, and smart, and interesting. But I think it concedes too much to really existing economics. In particular:

Obviously, macroeconomic phenomena are the aggregated (or, if you like, the emergent) consequences of microeconomic interactions.

No, that isn’t obvious at all. Two arguments.

First, for the moment, lets grant that macroeconomics, as a theory of aggregate behavior, needs some kind of micro foundations in a theory of individual behavior. Does it need specifically microeconomic foundations? I don’t think so. Macroeconomics studies the dynamics of aggregate output and price level, distribution and growth. Microeconomics studies the the dynamics of allocation and the formation of relative prices. It’s not at all clear — it certainly shouldn’t be assumed — that the former are emergent phenomena of the latter. Of course, even if not, one could say that means we have the wrong microeconomics. (Shalizi sort of gestures in that direction.) But if we’re going to use the term microeconomics the way that it’s used, then it’s not at all obvious at all that, even modified and extended, it’s the right microfoundation for macroeconomics. Even if valid in its own terms, it may not be studying the domains of individual behavior from which the important macro behavior is aggregated.

Second, more broadly, does macroeconomics need microfoundations at all? In other words,do we really know a priori that since macroeconomics is a theory of aggregate behavior, it must be a special case of a related but more general theory of individual behavior?

We’re used to a model of science where simpler, more general, finer-scale sciences are aggregated up to progressively coarser, more particular and more contingent sciences. Physics -> chemistry -> geology; physics -> chemistry -> biology -> psychology. (I guess many people would put economics at the end of that second chain.) And this model certainly works well in many contexts. The higher-scale sciences deal with emergent phenomena and have their own particular techniques and domain-specific theories, but they are understood to be, at the end of the day, approximations to the dynamics of the more precise and universal theories microfounding them.

It’s not an epistemological given, though, that domains of knowledge will always be nested in this logical way. It is perfectly possible, especially when we’re talking societies of rational beings, for the regular to emerge from the contingent, rather than vice versa. I would argue, somewhat tentatively, that economics is, with law, the prime example of this — in effect, a locally law-like system, i.e. one that can be studied scientifically within certain bounds but whose regularities become less lawlike rather than more lawlike as they are generalized.

Let me give a more concrete example: chess. Chess exhibits many lawlike regularities and has given rise to a substantial body of theory. Since this theory deals with the entire game, the board and all the pieces considered together, does it “obviously” follow that it must be founded in a microtheory of chess, studying the behavior of individual pieces or individual squares on the board? No, that’s silly, no such microtheory is possible. Individual chess pieces, qua chess pieces, don’t exist outside the context of the game. Chess theory does ultimately have microfoundations in the relevant branches of math. But if you want to want to understand the origins of the specific rules of chess as a game, there’s no way to derive them from a disaggregated theory of individual chess pieces. Rather, you’d have to look at the historical process by which the game as a whole evolved into its current form. And unlike the case in the physical sciences, where we expect the emergent phenomena to have a greater share of contingent, particular elements than the underlying phenomenon (just ask anyone who’s studied organic chemistry!) here the emergent phenomenon — chess with its rules — is much simpler and more regular than the more general phenomenon it’s grounded in.

And that’s how I think of macroeconomics. It’s not an aggregating-up of a more general theory of “how people make choices,” as you’re told in your first undergrad economics class. It is, rather, a theory about the operation of capitalism. And while capitalism is lawlike in much of its operations, those laws don’t arise out of some more general laws of individual behavior. Rather they arose historically, as a whole, through a concrete, contingent process. Microeconomics is as likely to arise from macroeconomics as the reverse. The profit-maximizing behavior of firms, for example, is not, as it’s often presented, a mere aggregating-up of utility maximizing behavior of individuals. [1] Rather, firms are profit maximizers because of the process of accumulation, whereby the survival or growth of the firm in later periods depends on the profits of the firm in earlier periods. There’s no analogous sociological basis for maximization by individuals. [2] Utility-maximizing individuals aren’t the basis of profit-maximizing firms, they’re their warped reflection in the imagination of economists. Profit maximization by capitalist firms, on the other hand, is a very powerful generalization, explaining endless features of the social landscape. And yet the funny thing is, when you try to look behind it, and ask how it’s maintained, you find yourself moving toward more particular, historically specific explanations. Profit maximization is a local peak of lawlikeness.

Descend from the peak, and you’re in treacherous territory. But I just don’t think there’s any way to fit (macro)economics into the mold of positivism. And there’s some comfort in knowing that Keynes seems to have thought along similar lines. Economics, he wrote, is a “moral rather than a pseudo-natural science, a branch of logic, a way of thinking … in terms of models joined to the art of choosing models which are relevant to the contemporary world.” It’s purpose is “not to provide a machine or method of blind manipulation, which will furnish an infallible answer, but to provide ourselves with an organized and orderly way of thinking about our particular problems.” (Quoted in Carabelli and Cedrini.)

[1] Economist readers will know that most mainstream macro models, including the “saltwater” ones, don’t include firms at all, but conduct the whole analysis in terms of utility-maximizing households.

[2] This point is strangely neglected, even by radicals. I heard someone offer recently, as a critique of a paper, that it assumed that employers behaved “rationally,” in the sense of maximizing some objective function, while workers did not. But as a Marxist that’s exactly what one should expect.

EDIT: Just to amplify one point a bit:

I suggest in the post that universal laws founded in historical contingency is characteristic of (some) social phenomena, whereas in natural science particular cases always arise from more general laws. But there seems to be one glaring exception. As far as we know, the initial condition of the universe is the mother of all historical contingencies, in the sense that many features of the universe (in particular, the arrow of time) depend on it beginning in its lowest entropy (least probable) state, a brute fact for which there is not (yet) any further explanation. So if we imagine a graph with the coarse-grainness of phenomena on the x-axis and the generality of the laws governing them on the y-axis, we would mostly see the smoothly descending curve implied by the idea of microfoundations. But we would see an anomalous spike out toward the coarse-grained end corresponding to economics, and another, somewhat smaller one corresponding to law (which, despite the adherents of legal realism, natural law, law and economics, etc., remains an ungrounded island of order). And we would see a huge dip at the fine-grained end corresponding to the boundary conditions of the universe.

FURTHER EDIT: Daniel Davies agrees, so this has got to be right.

Western Capital to China: Please Keep Wages Down

In today’s issue of the Financial Times, there’s a remarkably blunt warning that “Rising wages will burst China’s bubble.” True, China has enjoyed strong growth while most of the rest of the world has endured deep depressions. But don’t be fooled by such superficial measures. On the question that really counts, China is in trouble: “The Shanghai market is at less than half its all-time high, significantly underperforming the other three members of the Bric group.” Like Japan in the immediate postwar period, the piece argues, China has so far seen “workers flooding into the cities from the countryside, depressing wages and setting off a virtuous cycle of rising profitability and rising investment. In the mid-1950s, Japanese labour had taken 60 percent of total value added. in the miracle years, this ratio fell to 50 percent.” Miraculous indeed — but alas, it couldn’t last. By 1980, the labor share “had soared to a plateau of 68 percent. These gains had to be fought for. In the 1970s, Japan’s now dormant union movement was in its heyday. Profit margins were squeezed, and in real terms the stock market went nowhere for a decade.” Oh noes! And despite seemingly abundant reserves of cheap labor, the same disaster could befall China. “Can workers grab a larger share of the economic pie before the urbanization process is complete? In Japan they did. … If China were to follow Japan, the next stage would be labour strife and inflation. The best way to avoid that outcome would be a radical tightening of the current super-easy monetary policy. But that would risk a serious slowdown and probably necessitate a large revaluation of the renminbi.” So there it is. The important question about China’s future is the value of financial assets. And the great threat to asset-owners is the likelihood of rising wages, which will come about through increasing organizing among Chinese workers. The only way to prevent that is pre-emptive tightening, even at the cost of slower growth. The case for austerity is seldom made that bluntly, certainly not for the rich countries, but I don’t think the underlying motivation is much different. It’s also noteworthy that big revaluation of the renminbi is presented here explicitly as part of a program to hold down Chinese wages. In other words, China faces a choice between higher wages and a higher currency. To China-competing firms and workers in the rest of the world, either would be just as welcome. But for masters of the universe with Chinese stocks in their portfolio, they look very different indeed.
(Incidentally, these questions — the relationship between profitability, investment, demand, inflation and the politically-determined division of output between labor and capital — are largely ignored by mainstream macro, saltwater as well as fresh, but are right at the center of structuralist, Marxist, post-Keynesian and other heterodox approaches to macroeconomics. If only there were some economics department interested in supporting those approaches.)
EDIT: There was a link on a Something Awful thread sometime around March 20 that’s sending a lot of traffic to this post. Unfortunately, not being an SA member, I can’t see the thread. Anyone want to tell me what it was, in comments?

Net and Gross, or What We Can and Cannot Learn from Balance Sheets

One of the less acknowledged of the secret sins of economists, it seems to me, is the failure to distinguish between net and gross quantities, or to treat the net numbers if they were all that mattered. Case in point, the issue of deleveraging, where the good guys — the anti-austerians — are trying to get an accounting-identity argument to do more work than it it’s capable of. A good example is this post from Peter Dorman (which Krugman liked), which points out that in a closed economy one agent’s debt is always another agent’s asset, and total consumption must equal total income. So the only way that one agent can reduce its net liabilities is for another’s to increase, just as the only way some agents can spend less than their income is for others to spend more. In this sense increased public debt is just the flipside of private-sector deleveraging; arguments that the public sector should reduce its debt along with the private sector are incoherent. QED, right? Except, this argument proves too much. It’s true that one agent’s net financial position can’t improve unless another’s gets worse. But the same accounting logic also means that financial claims across the whole economy always sum to zero. Total net worth is always equal to the sum of tangible assets, no matter what happens on the financial side. [1] So it’s not clear what leveraging and develeraging could even mean in these terms. So, since the words evidently do mean something, it seems they’re not being used in those terms. It seems to me that when people talk about (de)leveraging, they are almost always talking about gross financial claims, not net, relative to income. A unit that adds $1,000 in debt and acquires a financial asset valued at $1,000 is more leveraged than it was before. And in this gross sense, it is perfectly possible for the public and private sector to simultaneously deleverage. Consider the following very simple economy, with just two agents:

T1
Income Assets Liabilities Net Worth
A 1 4 3 1
B 1 5 2 3
Total 2 9 5 4
T2
Income Assets Liabilities Net Worth
A 1 3 2 1
B 1 4 1 3
Total 2 7 3 4

The transition from T1 to T2 involves simultaneous deleveraging — in the economically meaningful sense — by both the agents in the economy, and no national accounting identities are violated. What would this look like in practice? To some extent, it could simply mean netting out offsetting financial claims, but that only really works within the financial sector; nonfinancial actors don’t generally hold financial assets and liabilities at the same time without some good institutional reason. (A firm may both receive and extend trade credit, but those two lines on the balance sheet can’t be netted out unless we want to go back to a cash-on-the-barrelhead economy. A typical middle-class household has both retirement savings and a mortgage and student-loan debt; both the borrowing and saving are sufficiently subsidized and tax-favored that it makes sense to add to the IRA rather than paying off the debt. [2]) To the extent that this kind of deleveraging does take place within the nonfinancial sector, it requires that units reduce their gross saving, i.e. their acquisition of financial assets — a suggestion that will seem even more paradoxical to conventional wisdom than the claim that private-sector deleveraging requires increased public debt. [3] But there’s another approach. Most borrowing by households and nonfinancial firms and households is undertaken to finance the acquisition of a tangible asset — in the table above, we should really divide the assets column into tangible assets and financial assets. For the low net worth units, most assets are tangible; for middle-class households, the house is by far the biggest asset, while property, plant and equipment is generally the biggest item on the asset side of a nonfinancial firm’s balance sheet. So the most natural way for the private sector and the public sector to deleverage is through a transfer of tangible assets from debtor to creditor units, combined with the extinction of the debts associated with the assets. This is, in essence, what privatization of public assets is supposed to do, when the IMF imposes it as part of a structural adjustment program. And more to the point, it’s what the foreclosure process, in its herky-jerky way, is doing in the housing market. At the end of the road, there’s a lot less mortgage debt — and a lot more big suburban landlords. [4] And the private sector has reduced its leverage, without any increase in the public sector’s. (Of course, we could just extinguish the debt and skip the asset-transfer part. But that default could be a means of deleveraging is one of those thoughts you’re not allowed to have.) Now, all this said, I completely agree with Dorman’s conclusion, that reducing public debt would hinder rather than help deleveraging. (Or rather, what he thinks is his conclusion; the real logic of his argument is that nothing can help or hinder deleveraging, since — like motion — it does not exist.) But the reason has nothing to do with balance sheets. It is because I believe that fiscal consolidation will reduce aggregate income — the denominator in leverage. I reckon Dorman (and Krugman) would agree. But this an empirical claim, not one that can be deduced from national accounting identities.
[1] Or the sum of tangible assets and base money, if you don’t treat the latter as a liability of the government. This is a question that gets people remarkably worked up, but it’s not important to this argument. (Or to any other, as far as I can tell.) [2] Actually I suspect many middle-class households are saving more than is rational — they’re acquiring financial assets when paying down debt would have a higher return. But anyone who knows me knows how comically unsuited I am to have opinions on anyone else’s personal finances. [3] Reducing debt and and expenditure simultaneously doesn’t help, since one unit’s expenditure is another’s income. For financial deleveraging to work, people really do have to save less. [4] Who might or might not end up being the banks themselves.

Roubini, Deflationist

Last week, Nouriel Roubini wrote a somewhat puzzling op-ed in the Washington Post, in support of a payroll tax cut as a stimulus measure.

It’s a rather strange argument, or mix of arguments, since he’s never clear whether it’s a demand-side or supply-side policy. For example, he argues both that the cut should be higher for low-income workers (since they have a higher propensity to consume), and that “to maximize the incentives for private-sector hiring, there should be sharper reductions to the payroll taxes paid by employers than for those paid by employees.”

But let’s take the supply-side half of Roubini’s argument at face value. Suppose a payroll tax cut lowered the cost of labor to employers. Is it so obvious that would increase employment?

The implicit model Roubini is using is the one every undergraduate learns, of a firm in a perfectly competitive market with increasing marginal costs. But in the real world firms face downward-sloping demand curves, especially in recessions. So the only way a reduction of labor costs can increase hiring is if it allows firms to lower costs, i.e. contributes to deflation. Does Roubini really think that more deflation is what the economy needs? (Does he even realize that’s what he’s arguing?)

This, anyway, was my reaction when I read the piece. But it wouldn’t be worth dragging out a week-old op-ed to take shots at, if my friend Arin hadn’t pointed out a recent NY Fed working paper by Gauti Eggerston making exactly this point. From the abstract: “Tax cuts can deepen a recession if the short term nominal interest rate is zero, according to a standard New Keynesian business cycle model. An example of a contractionary tax cut is a reduction in taxes on wages. This tax cut deepens a recession because it increases deflationary pressures.” The paper itself involves building up a complicated model from microfoundations (that’s why Eggerston gets paid the big bucks) but the underlying intuition is the same: The only way a decrease in labor costs can lead to increased hiring is by lowering prices, and under current conditions lower prices can only mean lower aggregate demand.

As Arin points out, the incoherence of the argument for payroll tax cuts may be precisely their appeal. People who think unemployment is the result of inadequate demand and people who think it’s the result of lazy, overpaid workers (i.e. it’s “structural”) can both support them, even though the arguments are incompatible. (People who don’t scruple too much over consistency can even make both arguments at once.) But if macroeconomic policy is limited to stuff that can be supported with bad arguments, we shouldn’t be surprised if the results are disappointing. That lower labor costs don’t help in a recession is, I guess, another lesson from the Great Depression that will have to be learned again.

As for Roubini, it’s hard to improve on Jamie Galbraith’s very diplomatic judgment: I cannot discern his methods.

Macro Models and the Long Run

I was just looking at this working paper on the OECD’s new global macro model. What it is, is a set of equations relating a dozen or so macro aggregates for each major country or region in the OECD, at a quarterly timescale. OK, that sounds stupid and naive to economists, and hopelessly cryptic to everyone else. Let’s proceed. Some observations, first on structure, second on content. On form:
The equations comes in two flavors, long-term and short-term. Salient fact about the long-term ones is that most of them are imposed (singly or jointly) rather than estimated. For instance, the elasticities of consumption with respect to income and wealth are constrained to sum to one. The elasticity of employment with respect to real wages is constrained to be negative one. (Oh, that one makes me mad.) The elasticities of exports and imports with respect to their respective market sizes are constrained to be one. And so on. Meanwhile, the short-term (one- and two-year) equations are allowed to be determined by the data.

There’s a couple reasons for this, at least one of which is reasonable. The reasonable one is that they want the long-run behavior of the model to converge to an equilibrium. If, let’s say, the long-run elasticity of imports with respect to income was anything but 1, the share of imports in consumption would rise without limit over time. I’m not sure how I feel about this. (Bad blogger!) On the one hand, it’s obviously true that that imports or consumption relative to GDP, or the wage share, or relative prices among trading patterns, don’t diverge to infinity. On the other hand, time doesn’t pass to infinity either. The practical relevance of the long-run conditions is only for a period long enough that exogenous fluctuations have canceled out, yet short enough that the parameters of the model remain unchanged. It’s not at all clear to me that the set of such periods is not empty. On the other hand, there may be reasons why postulating a long-run equilibrium is useful, even if we recognize that no such equilibrium is ever reached.

The other reason for the long-run restrictions is less defensible — or, since really who cares about my opinion, let’s say it’s substantive rather than methodological. The model “combines short-term Keynesian-type dynamics with a consistent neoclassical supply-side in the long run.” (Interestingly, mainstream macro has this in common with a major strand of Marxist economics, in contrast with the (post-)Keynesians who allow a role for demand even in the long run.) So some of the long-run restrictions are imposed not simply to get an equilibrium, but to get a particular, tastes-endowments-and-technology equilibrium. There’s no reason in principle that practical macroeconomics should exclude the possibility of changes in real wages changing income shares in the long run. That the OECD does, tells you something.

On to the substance:

A couple interesting things here, which unlike the thumbsucking above, one can actually use. These are hardly gospel, of course; but enshrined in the OECD macro model they can be taken as stylized facts, in the sense that in many contexts they don’t, qualitatively, have to be explicitly argued for.
1. Wealth effects (on consumption) are largest for the US, smallest for Japan.
2. The effect of import prices on the domestic price level is negligible in the US and Japan, but substantial in Europe.
3. Trade flows are much more responsive to income changes than to relative prices. Estimated export elasticities are two to three times higher for income than for “competitiveness” [3]; estimated import elasticities are two to four times higher.
4. US export prices move with domestic prices essentially one for one; US import prices move with foreign prices only slightly. For most other countries, export pass-through is lower and import pass-through is greater.

The last two are particularly interesting.

Eventually, one would like to think through the conceptual basis, and limits, of these sorts of models. There’s that never-realized long-term. Meanwhile here in the short-term, when you’re making heterodox arguments it’s nice to get empirical backup from some place impeccably orthodox.

What is Keynesianism?

[A bit of thumbsucking inspired by discussion here.]

As a policy of countercyclical demand management, Keynesianism is based on the idea that there are no automatic forces in industrial capitalism that reliably equilibrate aggregate supply and aggregate demand. In the absence of government stabilization policies, the economy will waver between inflationary periods of excess demand and depressed periods of inadequate demand. The main explanation for this instability is that private investment depends on long-term profitability expectations, but since aspects of the future relevant to profitability are fundamentally uncertain [1], these expectations are unanchored and conventional, inevitably subject to large collective shifts independent of current “fundamentals”. Government spending can stabilize demand if G+I varies less over the business cycle than I alone does. For which it’s sufficient that government spending be large. It’s even better if G and I move in opposite directions, but the reason Minsky answered No to Can “It” Happen Again? was because of big government as such, not countercyclical fiscal policy.The 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. [2] There is not, however, any corresponding long-term increase in the demand of 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. [3] 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. (Here is a respectable mainstream guy making essentially this argument. [4]) 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.
[1] Davidson, Shackle, etc. would say nonergodic. This strand of Post Keynesian thinking often wanders beyond my comfort zone.[2] This shift is ongoing, not just historical — not only do capital-output ratios continue to rise in manufacturing, but we’re seeing the “industrialization” of retail, health care, etc.

[3] Schumpeter is the only major economist to give sufficient attention to the sociology of the capitalist class, IMO. Marx’s insistence that the capitalist is simply the human representative of capital is a powerful analytic tool for many purposes, but it leaves some important questions unasked.

[4] Here is another.

What’s wrong with macroeconomics

Really, you could start anywhere.

But let’s take this, from VoxEU:

In a recent paper (Laibson and Mollerstrom forthcoming), my co-author David Laibson and I make further attempts to assess whether the saving glut hypothesis fits with reality. We build a model where one country (the US) receives exogenous capital inflows which are calibrated to match the US current account deficits for the period that Bernanke was focusing on. Our model shows us that such a course of events should indeed lead to increases in US consumption. However, we also find that the investment rate should have risen by at least 4% of GDP. Intuitively this makes sense; if the Chinese government exogenously loaned US households a trillion dollars, those US households should have chosen to invest a substantial share of those funds to help make the interest payments.

What’s missing here? Businesses, one, and the financial system, two. Investment decisions are supposed to be made directly by households. Of course writers like this (a grad student and professor at Harvard, natch) know that firms and banks exist; they just assume that there are no important differences between an economy with them and one without them — the standard approach, despite its seeming self-refuting quality, to macroeconomics today. This will seem trivially obvious to anyone who’s taken a macro course, and astonishing to almost anyone who hasn’t; it’s still a bit astonishing to me. It’s nice to be reminded, though, of why post-Keynesian and Marxist approaches to macroeconomics are still essential.