My take on the Acemoglu-Robinson critique of Piketty

A couple of days ago Daron Acemoglu and James Robinson published a critique of Piketty’s Capital in the 21^st century. It is published here.  Because of the renown of the authors, perhaps more than because of its intrinsic quality, it is a review worth reading. I read it today and my brief reaction to the three main critiques by Acemoglu and Robinson is as follows.

1) Piketty totally neglects institutions. This is hard to understand since Piketty's explanation for a large part of changes in inequality in the US, France and elsewhere are precisely institutional: higher and then lower income and inheritance tax rates, abolition of slavery. It is so much so that in my class and presentations I have dubbed  Piketty's approach "a political theory of income distribution". So I really fail to see any validity in this critique. 

Actually, that part of the critique is fundamentally dishonest. It proceeds as follows. First, Acemoglu and Robinson establish the equation Piketty=Marx. Then then criticize Marx for ignoring institutions, more or less correctly (but clearly that has nothing to do with Piketty). Then, since they have already decided that Piketty is really Marx, they barely give one or two examples of Piketty’s lack of concern with institutions and discuss, as many authors have done before, Piketty’s “fundamental laws”. They seem to imply that having “fundamental laws” (never mind that these laws are an identity and a dynamic equilibrium condition) somehow means that one does not care about institutions.  Very bizarre.

2) Lots of inequality increase is due to higher inequality of labor incomes. This  is true especially for the United States and no one disputes it; neither does Piketty. He actually mentions it repeatedly especially when he discusses the increasing share of labor incomes in the top 1%. But he is also aware of potentially very high inequality which may exist when both capital and labor incomes are  heavily concentrated and often among the same people.  In other words, just saying that inequality is driven by rising concentration of labor incomes does not make such inequality “benign” and somehow “fair”.

3) Panel regressions. This is a novelty. Acemoglu and Robinson test whether r-g is correlated with increase in inequality (measured by the top 1% share). They find that the sign of the coefficient is in most cases negative, that is different from the one predicted by Piketty. This is a good approach and I am sure it will be repeated a number of times. I expect an entire cottage industry of similar cross-country regressions trying to prove or disprove Piketty’s contention.  Acemoglu and Robinson’s first set of regressions assumes an equal _net_ rate of return for all countries. Thus the right-hand side variable is not r-g but simply “g”. This approach  is surely wrong. Piketty's rate of return  is defined after taxes which are of course not the same in all countries. It is not at all obvious that all countries face even the same gross rate of interest, much less that the net or gross rate of return to capital is the same. Thus only the second set of Acemoglu-Robinson regressions with national estimates of rates of return makes sense. But there, the results are inconclusive. Moreover, there are no usual controls at all except for the country and year dummies. What would be the results if one introduced policies and outcomes with respect to labor, taxation, government expenditures, level of income and  the panoply of the usual controls that we use in inequality regressions? And aren't time dummies precisely related to Piketty's argument about (say)  globalization and tax competition holding r high?  But they are not discussed at all.

Finally, I agree with their point that the focus on top shares is limited and that lots of important changes take place along the entire income distribution. But as well known, the focus on top shares is driven by the very nature of fiscal data used by Piketty and his coauthors.

I do not discuss Acemoglu-Robinson  analysis of South Africa vs. Sweden increase in inequality because I really fail to see a great virtue in it. As I unfortunately have to confess, I often find reading Acemoglu-Robinson descriptions of political changes quite superficial: they read like Wikipedia entries with regressions. I had the same feeling here too.

Mr. Piketty and the classics

For a seminar in Oslo on September 4, I was asked (although I did not expect it) to speak of the significance for economics, and especially economics of inequality, of  Piketty’s recent work.  So I decided in this brief note to put some thoughts together.

The major contribution of Piketty is, in my opinion,  a (I did not say “the”) general theory of laws of motion of capitalism which  combines theories  of growth, factoral income distribution and personal income distribution.  (For those who have read my review in JEL, this is not a new opinion. I thought so already in October 2013 when I read Piketty’s book and wrote the review. ) Theories of growth and factoral income distribution were always related, but the explicit connection from factoral to personal income distribution, substantiated with a  huge amount of empirical evidence, gives to Piketty’s work a new, and unique, value.  

 As in many ground-breaking pieces of work, it is not that each individual part is novel and something that nobody before ever thought up. Clearly, neoclassical growth theory goes  fifty or more years back. Even the discussion of personal income distribution  in the book comes from Piketty’s own previous work, as well as that of his colleagues Tony Atkinson,  Emmanuel Saez and Facundo Alvaredo. To somebody familiar with  15 years  of that literature, there is again, not much new in Capital in the 21st century. But it is the combination of the three elements  I mentioned before that gives the book its unique color  and importance. Thus the whole is greater than the sum of the parts. 

Let me now address the key parts of Capital which have received so much attention: Piketty view about the inexorable tendency towards income divergence in capitalist economies left to themselves, and his proposed remedy. There I think we need to distinguish five propositions.

1. Wealth. As  economies become richer, the capital-output (K/Y) ratio increases. The increase in K/Y  is nothing else but the definition of a rich economy: over the years (decades) people save, productivity increases, and economies become more capital-intensive.  In an economy where wealth is privately-owned,  individual wealth increases and people become richer.

 2. Distribution. In capitalist economies, historically and without a single exception, wealth and income from wealth are  distributed more unequally than labor income. The share of total wealth held by the top 1% of wealth-holders is greater than the share of total earnings  made by the top 1% of  wage-earners. Or differently, the Gini of capital income is greater  than the Gini of labor income. Or even more importantly, the concentration coefficient is greater for income from capital than income from labor. (The concentration coefficient is important because in its calculation, people are ranked by their total income and a high concentration coefficient does not mean only that wealth-holding is concentrated but also that it is concentrated in a particular fashion such that owners of wealth are generally rich in terms of total income too. To see the difference, notice that unemployment benefits are also heavily concentrated but their recipients are poor and the  concentration coefficient of unemployment benefits will be low or negative.)

3. Inter-personal inequality. Point 2 implies that any increase in the share of capital income will be associated with an increase in inter-personal inequality. 

4. r>g. If then income from capital increases faster than total income (or, by implication than income from labor) functional income distribution will shift toward capital, and personal  income distribution will become more unequal.  As rich economies have high K/Y ratios and if r is grater than g, income from capital will gradually tend to dominate income from labor. At the extreme, say K/Y=100 (vs. the current K/Y=6 or 7), even an r=0.5% will give ½  of national income to capital-owners. 

5. Taxation. To arrest this natural tendency of capitalism, a solution is progressive taxation of capital which will reduce r below g. It might affect the speed with which capital accumulates (although Piketty thinks that it will not), and slow down the increase in K/Y.

I think it is important to distinguish each of these five statements. No. 1 is empirically true (it is moreover the very definition of wealth). 

No. 2 is empirically true, although the rising concentration of labor incomes which we witness especially in the United States, may, in the future, reduce the universal validity of capital being more heavily concentrated than labor. But we are still far from it, with Ginis from capital income at 0.8, and Ginis of labor income at 0.4. However, a recent and important (yet unpublished) work by Christoph Lakner shows that in the US, the probability of a person having a high labor income also having a high capital income is greater than the reverse probability, of a person with high capital income having also a high labor income.  So we may be moving toward the emergence of a peculiar capitalism with high concentrations of both labor and  capital incomes.  

No 3 is also empirically true, with a caveat that I just mentioned and which might apply in the future. Notice however that a very high concentration of both labor and capital incomes and their high association will make overall inequality extremely high, perhaps even higher than it is today, but the source of that inequality will be different, that is will derive from high concentration of labor and capital incomes and not predominantly from the latter only.

So, the first three propositions are empirically incontrovertible: all the evidence that we have so far supports them. We cannot be sure that 2 and 3 will continue to behave in the future as they did in the past, but the likelihood of happening  so is very high.  

We now come to No. 4 which is a statement about the future and which has exercised Piketty’s critics a lot. But note that all his previous three statements are true, and while the future might hold a g>r rather than r>g, Piketty’s methodological contribution to our way of thinking about  wealthy capitalist economies is not diminished by whichever way r and g behave. The model holds whether r>g or g>r.

Thus, it is consistent to think both that Piketty’s contribution is enormous and that in  the future, the growth rate of the economy may be greater than the rate of return to capital. For example, with globalization r will tend to be kept  high for the reasons mentioned by Piketty and to be the same worldwide (so r=r* given to all), but the growth rates of the emerging economies like China and India may remain even higher. Thus, in China and India, we may have g>r* and the downward movement in inequality, while in the developed world, we may have r*>g, and increases in inequality as envisaged by Piketty. 

Finally, we come to proposition 5 which has also attracted huge interest. There one can too disagree with Piketty’s proposal, not the least because one may find it unrealistic. But there is no denying that the proposal derives  directly from the propositions  1-4, so we are dealing with a logically consistent set of analysis and prescription. 

There are, in conclusion, I think three different ways in which some of Piketty’s “predictions” may be falsified without, and I emphasize again, in any way affecting his key methodological contribution. The three different ways are: labor incomes may become more concentrated, the growth rate may exceed the rate of return to capital in many countries, global taxation of capital may not happen.

At the end, I would like to compare Piketty’s approach to Ricardo’s. Both authors have proposed a formidable model of development of capitalism which was based on the observable tendencies  of their times, and the projection of these tendencies in the future—unless they be checked by a change in economic policies.  In Ricardo’s case, that was free trade in grain; in Piketty’s case, taxation of capital. Ricardo’s model of ever increasing share of rent in national income was of course falsified, but, it could be argued, it was falsified exactly because his policy prescription was adopted in England. In the same way, Piketty’s model may also be falsified if his policy prescription is adopted. 

In the table below, I give in a very summary fashion some of the key things that, in my opinion, remain from the great economists of the past—even when many of their predictions did not materialize, whether because their policy prescriptions, as in the cases of Ricardo and Keynes, were adopted or, because, as in the cases of Marx, Pareto and Schumpeter, they were simply wrong. But even when the latter happened, the predictions that failed referred only to a part of their work, and the greatest body of their work is something without which today’s economics would be unimaginable and indeed much poorer. So, my point is, even if some of Piketty’s predictions  fail, be it because his idea of global taxation of capital indeed reverses inequality tendencies, or because inequality goes down for other reasons, his main contributions will be integrated in the corpus of economic knowledge in the same way as the insights of these great economists listed here were. And our understanding of economies will never be the same as it was before Capital in the 21^st century was published.  

	Things that remain	Wrong predictions	Policy
Ricardo	Dynamic model of a capitalist economy	Subsistence wages Increasing share of income from land	Help capitalism through free trade
Marx	Two-sector model Historical materialism	Subsistence wages Tendency of the profit rate to fall End of capitalism	Nationalization of the means of production as a way to transcend capitalism
Walras	General equilibrium		Nationalize land and use rent income in lieu of taxes
Pareto	Pareto-type of concentration among top incomes	Income distribution is ruled by an “iron law”: inequality can never change (circulation of the elites)	[Do nothing]
Keynes	Focus on macro Real sector and financial sector equilibrium considered jointly	Euthanasia of the capitalist	Help capitalism by stabilizing it through a greater state role
Hayek	Decentralized nature of economic information	Every state intervention is a step on the road to serfdom	Limited state action
Schumpeter	Financially-driven movement from a stationary state to a developing state	Capitalism will be rejected by the intelligentsia
Kuznets	Inequality changes with economic development	Inequality in rich countries will go down
Piketty	Personal income distribution unified with functional		Help capitalism by taxing capital