Tag Archives: lance taylor

RIP, Lance Taylor

Lance Taylor has passed away.

Among other things, he promoted stock-flow consistent modeling. He had a book Reconstructing Macroeconomics.

I hold dear the review of Lance Taylor of Wynne Godley’s work, titled: A Foxy Hedgehog: Wynne Godley And Macroeconomic Modelling.

The article starts:

The fox knows many things, but the hedgehog knows one big thing (Archilochus, seventh century BCE).

Lance Taylor clearly understood the importance of accounting. In the paper A Simple Model Of Three Economies With Two Currencies, Wynne Godley and Marc Lavoie quote him:

As pointed out by Taylor (2004, p. 206), ‘the best way to attack a problem in economics is to make sure the accounting is right’.

Bibliography

Taylor, L. 2004. Exchange rate interderminacy in portfolio balance, Mundell–Fleming and
uncovered interest rate parity models, Cambridge Journal of Economics, vol. 28, no. 2, 205–27

Here’s the link to that Lance Taylor paper.

Stock-Flow Inconsistent?

The first rule of Post-Keynesian Economics is: You do not talk make accounting mistakes. The second rule of Post-Keynesian Economics is: You do not talk make accounting mistakes.

– Anonymous.

Jason Smith—who is a physicist—but writes a blog in Macroeconomics, wonders how equations in the simplest stock-flow consistent model given in the textbook Monetary Economics written by Wynne Godley and Marc Lavoie make any sense from a dimensional analysis viewpoint.

He says he

seem[s] to have found a major flaw.

He sees the equation:

ΔH = GT

and wonders where the time dimensions are. For, H is the stock of money and hence has no time dimension, whereas the right hand side has flows and has time dimensions of inverse of time. For example if the US government spends $4 tn in one year, is $4 tn/year.

In continuous time, the above equation is:

dH/dt = GT

So how are these two equations the same?

Perhaps, Jason is not familiar with difference equations. He instead seems to prefer:

τ·ΔH = GT

Well that’s just wrong if τ is anything different from 1, as a matter of accounting.

Now moving on to time scales, it is true that in difference equations some time scale is implicit. But it doesn’t mean the methodology itself is wrong. Many physicists for example set all constants to 1 and then talk of numbers which are dimensionless.

So if a relativist sets “c=1”, i.e, the speed of light to 1, all velocities are in relation to the speed of light. So if somebody says the speed is 0.004, he/she means the speed is 0.004 times the speed of light.

But Jason Smith says:

Where does this time scale come from over which the adjustment happens? There is some decay constant (half life). It’s never specified (more on scales here and here). If you think this unspecified time scale doesn’t matter, then we can take Δtlp and the adjustment happens instantaneously. Every model would achieve its steady state in the Planck time.

That’s not true. String theorists for example set the parameter α’ = 1. But nobody ever claims that macroscopic adjustments happen at Planckian length scales or time scales.

Coming back to economics, there’s nothing wrong in

ΔH = GT

There’s an implicit time scale yes, such as a day, or a month, or a year, or even an infinitesimal. But parameters change accordingly. So in G&L models we have the consumption function

 C = α1 ·YD + α2 ·W

where is household consumption, YD, the disposable income and W, the household wealth.

Let’s say I start with a time period of 1 year for simplicity. αmight be 0.4. But if I choose a time period of 1 quarter, αwill correspondingly change to 0.1. In English: if households consume of 4/10th  of their wealth in one year, they consume in 1/10th one quarter.

So if we were to model using a time scale of a quarter instead of a year, α2 will change accordingly.

But the equation

ΔH = GT

won’t change because it is an accounting identity!

It’s the difference equation version of the differential equation:

dH/dt = GT

Physicists can pontificate on economic matters. I myself know string theory well. But boy, they shouldn’t make mathematical errors and embarrass themselves!

In other words, accounting identities can be written as accounting identities in difference equations. What changes is values of parameters when one chooses a time scale for difference equations.

Wynne Godley’s model is touched by genius. In fact according to one of the reviewers of Monetary Economics, Lance Taylor says that it is out of choice that Wynne Godley chose a difference equation framework. They can be changed to differential equations and we’ll obtain the same underlying dynamics.

Here’s Lance Taylor in A foxy hedgehog: Wynne Godley and macroeconomic modelling

Godley has always preferred to work in discrete time, responding to the way the data are presented.

Question: is the equation ΔH = Gconsistent with dimensional analysis?

Answer: Yes. H is the stock of money at the end of previous period. Δis the change in stock of money in a period. and are the government expenditure and tax revenues in that period. So H, ΔH, G and T have no times dimensions in difference equations. All are in the unit of account. Such as $10tn, $400bn, $4 tn, $3.6tn. Time dynamics is captured by model parameters.

In G&L’s book Monetary Economics, in Appendix 3 of Chapter 3, there’s a mean-lag theorem, which tells you the mean lag between two equilibrium (defined as a state where stock/flow ratios have stabilized):

it is:

[(1 − α1)/α2 ]· [(1 – θ)/θ]

where θ is the tax rate.

So, in the model, assuming a value of 0.6 for α1, 0.4 for α2, and 0.2 for θ we have the mean-lag equal to 4.

Let’s assume that time period is yearly. This means the mean lag is 4 years.

If instead, we were to use quarterly time periods, α2 would be 0.1 and the mean lag evaluates to 16, i.e., sixteen quarters, which is 4 years, same as before.

So there is really no inconsistency in stock-flow consistent models.

tl;dr summary: In difference equations, there’s nothing wrong with equations such as ΔH = GT. It is an accounting identity. By a choice of a time scale, one implicity chooses a time scale for parameter values. What’s wrong? Jason Smith would obtain the same results as the simplest Godley/Lavoie model if he were to work in continuous time and write equations such as dH/dt = GT. I will leave it to him as an exercise!

Flow Of Funds And Keynesian Macroeconomics

The subject of money, credit and moneyflows is a highly technical one, but it is also one that has a wide popular appeal. For centuries it has attracted quacks as well as serious students, and there has too often been difficulty in distinguishing a widely held popular belief from a completely formulated and tested scientific hypothesis.

I have said that the subject of money and moneyflows lends itself to a social accounting approach. Let me go one step farther. I am convinced that only with such an approach will economists be able to rid this subject of the quackery and misconceptions that have hitherto been prevalent in it.

– Morris Copeland, inventor of the Flow Of Funds Accounts of the United States, in Social Accounting For Moneyflows, in Flow-of-Funds Analysis: A Handbook for Practitioners (1996) [article originally published in 1949]

Alas monetary myths continue to exist. The above referred handbook was published in 1996 starting with Copeland’s 1949 article and the editor of the book John Dawson himself had an explanation of why myths continue to exists despite some brilliant work such as that of Copeland. In page xx, Dawson says:

the acceptance of… flow-of-funds accounting by academic economists has been an uphill battle because its implications run counter to a number of doctrines deeply embedded in the minds of economists.

In a recent blog post blog post Paul Krugman is dismissive of Wynne Godley’s approach to macro modeling and instead appeals to some Friedmanism. Perhaps Dawson’s quote explains why this is so. However it may not be the only reason, given how Krugman has shown some tendency to be heteredox in recent times but his latest post ends all doubts and we can say he is highly orthodox. And that other reason is professional turf-defence.

Also, Krugman was writing in response to an NYT article Embracing Wynne Godley, an Economist Who Modeled the Crisis highlighting the importance of Wynne Godley’s work. That article was by a journalist who was perhaps unaware of the history of Post-Keynesianism. But Krugman himself dodged Godley’s work as “old-fashioned” – as if there is something fundamentally wrong about old-fashion and as if economics should proceed by one fashion after another.

A bigger disappointment is that Krugman failed to acknowledge that there has existed a heteredox approach since Keynes’ time. As Wynne Godley and Marc Lavoie begin Chapter 1 in their book Monetary Economics:

During the 60-odd years since the death of Keynes there have existed two, fundamentally different, paradigms for macroeconomic research, each with its own fundamentally different interpretation of Keynes’ work…

And Krugman’s usage of the phrase old-fashioned hides the fact that this is so.

Back to Copeland. In the same article Social Accounting For Moneyflows, Copeland is clear about his intentions and the direction he is looking:

When total purchases of our national product increase, where does the money come from to finance them? When purchases of our national product decline, what becomes of the money that is not spent? What part do cash balances, other liquid holdings, and debts play in the cyclical expansion of moneyflow?

Copeland’s analysis was not simply theoretical. It led to the creation of the flow of funds accounts of the United States and the U.S. Federal Reserve publishes this wonderful data book every quarter. Although, Copeland was simply looking and proceeding in the right direction, it can be said that a more solid theoretical framework to build upon Copeland’s brilliant work was still waiting at the time.

Of course, in the world of academics, there already existed two main schools of thought very hostile to one another. Keynes’ original work contained a lot of errors and for most economists, a bastardised version of Keynes’ work became the popular understanding. It was however the Cambridge Keynesians who founded the school Post-Keynesian Economics who believed they were true to the spirit of Keynes and this led to a parallel body of extremely high-quality intellectual work which continues to this day – and still dismissed by economists such as Paul Krugman. Of course, in this story, it should be mentioned that there was a Monetarist counter-revolution mainly led by Milton Friedman who was trying to bring back the old quantity theory of money doctrines and was “successful” in permanently distorting the minds of generations of economists to date. Greg Mankiw is quite straight on this and according to him, “New Keynesian” in the “New Keynesian Economics” is a misnomer and it should actually be New Monetarism.

Interestingly, one of Morris Copeland’s ideas was to show how the quantity theory of money is wrong. According to Dawson (in the same book referred above):

[Copeland] himself was at pains to show the incompatibility of the quantity theory of money with flow-of-funds accounting.

Meanwhile, in the 1960s and to the end of his life, James Tobin tried to connect Keynesian economics with the flow of funds accounts. While a lot of his work is the work of a supreme genius, he couldn’t manage. Perhaps it was because of his neoclassical background which may have come in the way. According to his own admission, he couldn’t connect the dots:

Monetary and financial data, so far as they are based on institutional balance sheets and prices in organized markets, are abundant. Modern machines have made it possible to improve, refine and expand the compilation of these data, and also to seek empirical regularities in financial behavior in the magnitude of individual observations. On the aggregate level, the Federal Reserve Board has developed a financial accounting framework, the “flow of funds,” for systematic and consistent organization of the data, classified both by sector of the economy (households, nonfinancial business, governments, financial institutions and so on) and by type of asset or debt (currency, deposits, bonds, mortgages, and so on). Although many people hope that this organization of data will prove to be as powerful an aid to economic understanding as the national income accounts, this hope has not yet been fulfilled. Perhaps the deficiency is conceptual and theoretical; as some have said, the Keynes of “flow of funds” has yet to appear.

– James Tobin in Introduction (pp xii-xiii) in Essays In Economics, Volume 1: Macroeconomics, 1987.

After having written a fantastic book Macroeconomics with Francis Cripps in 1983 and which has connections with the flow of funds, Wynne Godley thought he had to try hard to unify (post-)Keynesianism and the flow of funds approach which James Tobin was trying. Wynne Godley had the advantage of being close to Nicholas Kaldor who very well understood the importance of Keynes and was himself an economist of Keynes’ rank. Godley also had the advantage of having worked for the U.K. government and doing analysis using national accounts data and advising policy makers. Wynne Godley is the Keynes of “flow of funds” which Tobin was talking about!

A recent blog post by Matias Vernengo on Wynne Godley is extremely well-written.

In his later years (and his best), Wynne Godley worked with Marc Lavoie, one of the faces of Post-Keynesianism and one who had previously made highly original contributions to Post-Keynesianism and this led to the book Monetary Economics. Marc’s earlier work was also highly insightful and he highlighted – in the spirit of Morris Copeland – how poorly money is understood by economists in general and it was natural he and Wynne would meet and work together.

One of the things about Wynne Godley’s approach is how to combine abtract theoretical work and direct practical economic issues. This actually led him to warn of serious deflationary consequences of economic policy in fashion before the crisis.

Lance Taylor (in A Foxy Hedgehog: Wynne Godley And Macroeconomic Modelling) had a nice way to describe Wynne Godley:

Wynne has long been aware of the stupidity of models when you ask them to say something useful about practical policy problems. He has spent a fruitful career trying to make models more sensible and using them to support his policy analysis even when they are obtuse. As we have seen, this quest has led him to many foxy innovations.

But there is an enduring hedgehog aspect as well. Wynne has focused his energy on combining the models with his acute policy insight based on deep social concern to build up a large and internally coherent body of work. He has disciples and is widely influential. One might wish that he had pursued some lines of analysis more aggressively and perhaps put a bit less effort into others. And maybe not have written down so damn many equations. But these are quibbles. His work is inspiring, and will guide policy-oriented macroeconomic modellers for decades to come.

In this post, I have tried to provide the reader with references to go and verify how flow of funds1 cannot be separated from Keynesian Economics – Keynesian approach in the original spirit of Keynes, not some bastartized versions. It is as if they were made for each other2. While it is true that like other sciences, Macroeconomics is always work in progress, it doesn’t mean one should bring fashions such as inter-temporal utility maximising agents (read: future knowing economic actors) in the approach which Paul Krugman prefers.

1My usage of “flow of funds” is more generic than the usage which distinguishes income accounts and flow of funds accounts and hence my usage is for both.

2The ties between the flow of funds approach and Post-Keynesiansism is argued in Godley and Lavoie’s book Monetary Economics from which I have borrowed a lot.

Correction

I am mistaken about Jonathan Schlefer’s background. He is in academics.