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34th Barcelona GSE Lecture: Robert Lucas

March 29, 2016

Barcelona GSE Lecture

Lecture summary by Evan Seyfried ’16 (Master’s in Economics of Public Policy). Above, the author talks with Robert Lucas after the lecture.

The modish Banco Sabadell Lecture Hall, overlooking grand, prosperous Avinguda Diagonal, is filled to capacity this Thursday evening. Nobel laureate economist Robert Lucas is here to present the 34th Barcelona GSE Lecture, and the GSE community is eagerly anticipating the talk.

“What was the Industrial Revolution?”

The topic would have seemed almost trite in less-skilled hands. Lucas, however, over the past decade has focused his talents on exploring economic models that might explain rapid industrialization like that of the United Kingdom starting in the late 18th century. He views the rise of urbanization and industrialization through the lens of economist Gary Becker’s theory of population fertility and couples it with a human capital growth model.

This talk draws heavily from Lucas’s recent research on human capital and economic growth1, the diffusion of the Industrial Revolution2, and a rejection of the “great men” hypothesis of economic progress3.

The central hypothesis of his lecture tonight is, essentially, that of his 2015 paper on economic growth, with its blissfully short abstract:

“This paper describes a growth model with the property that human capital accumulation can account for all observed growth. The model is shown to be consistent with evidence on individual productivities as measured by census earnings data. The central hypothesis is that we learn more when we interact with more productive people.”1

From this basis, Professor Lucas presents his most recent work on the topic. He begins with a graph—how else would an economist begin any lecture?—showing the striking relationship between a country’s prosperity (measured in GDP per capita) and the share of its population employed in agriculture.


Graph depicting the relationship between agricultural intensity (“employment share of agriculture”) and national wealth (“log GDP per capita”). Source: Lucas (2009)2

Why is the relationship between these two variables so consistent? Later in the lecture, Lucas will develop his model based on a “dual economy” of low-skilled agricultural workers and various levels of skilled urban dwellers.

But first, a little history.

“Macroeconomics’ finest hour.” (A brief historical digression.)

Thomas Robert Malthus, English cleric and scholar, became famous (and, to some, infamous) when he published “An Essay on the Principle of Population” in 1798. The essay neatly distilled a framework for pre-industrial population dynamics:

“Yet in all societies, even those that are most vicious, the tendency to a virtuous attachment is so strong that there is a constant effort towards an increase of population. This constant effort as constantly tends to subject the lower classes of the society to distress and to prevent any great permanent amelioration of their condition.”4

Its publication led to a massive controversy that rapidly spread across the landscape of political economy. Although Malthus’s work was not nearly as apocalyptic as his deriders asserted, it still pointed out uncomfortable truths about the seemingly unrelenting misery of the lower classes, even in “advancing” nations.

A century and a half later, economist Gary Becker took up the Malthusian mantle with his seminal work, “An Economic Analysis of Fertility,” a study of the dynamics of family planning and income. Becker explicitly acknowledged his debt to Malthus: “[…] Malthus’ famous discussion was built upon a strongly economic framework; mine can be viewed as a generalization and development of his.”5 Becker’s further research concluded that viewing fertility as a result of marginal-cost/marginal-benefit decisions is a satisfying way to explain the phenomenon of high-income families voluntarily lowering their fertility rates. His framework implies that families with more human capital invest more resources in fewer children.

Professor Lucas calls the Malthusian insight and the subsequent robust debate among political economists of the day “macroeconomics’ finest hour.”

The Path Off the Farm: What Is an Industrial Revolution?

Lucas now presents his synthesis: Becker’s fertility model combined with Lucas’s own human capital model, both placed in the context of the urban-agricultural dual economy.

Like Becker, Lucas’s model has parents view their children as “durable goods” that yield a “psychic utility” but also impose costs. As families move up the socioeconomic ladder, they make different decisions regarding investment in the “quality” of the children (everything from time spent teaching, to money invested in tutors and private schools). Over time, the quantity/quality balance leads to lowering fertility among higher socioeconomic classes.

In the dual-economy framework, rural (landless or small proprietor) farmers are pushed by wage considerations to move into dynamic urban environments as low-skilled workers. At first, with no wealth to invest in their children, they make “quantity” a priority over “quality.” Over generations, however, there is a tipping point where a given family has accumulated enough resources to make meaningful human-capital investments in their children. Once this occurs, they can now move up to the higher-skilled tiers of society. Crucially, it is this accumulation, not of wealth, but of human capital, that drives further growth in Lucas’s model. The speed at which these changes occur depends on the magnitude of “interactions” in society: how often and to what degree people engage with one another in productive exchanges—anything from academic discussions to business deals.

A key mechanism in the model is that economic growth itself is what allows the low-skilled workers, coming from the farms, to dependably get better and better jobs over time. Thus, the dynamic is self-reinforcing as more rural workers move to the cities.

When considering the Industrial Revolution, we can appreciate how natural it would be to dismiss the intangible, fuzzy concept of “human capital” and only focus on material capital: factories, infrastructure, mines, etc. But if we view the Industrial Revolution with Lucas’s model in mind, we can at the very least see that Lucas’s statement from his 2015 paper—”human capital accumulation can account for all observed growth”1—is quite plausible.

Later in the same paper, Lucas asserts: “The contribution of human capital accumulation to economic growth deserves a production function of its own.” 1 In the model Lucas has presented tonight, he answers his own demand. There is, indeed, a “production function” for human capital, and when it is coupled to a fertility model, it can show the dynamics of rapid urbanization and economic growth. In other words, it can model an industrial revolution.

To use Lucas’s own words from the lecture: “We used to think of the Industrial Revolution as factories and coal, but I think the main consequence was the emergence of the bourgeoisie who are just creating things out of nothing, generating wealth and production.”


What does this all mean? What are the implications of this model in 2016?

We go back to the graph showing the relation between GDP per capita and share of population in agricultural work. Lucas mentions how many areas of the world are still in the upper left portion of the graph—poor, agricultural, unskilled-labor-intensive economies. According to Lucas, we must not be deluded into thinking that a pastoral lifestyle is something to be preserved at the cost of indefinite poverty. Lucas states, “The idea that you can prettify this lifestyle is just plain wrong.” Rather, we have a collective interest in the flourishing of all people around the world, and we have emerging evidence that investment in human capital, coupled with smart urbanization, is one of the best ways to achieve it.

The questions following the lecture are—as expected from economists—pointed. In response to questions about the refugee and economic migrant crisis in the EU, Lucas denies that his model says anything specific about it, but states emphatically that he supports immigration in general. Finally, when asked about the prospects of continued economic growth, given recent anxiety about economic stagnation, Lucas responds that since the Industrial Revolution we have seen stable growth unlike any period before in recorded history. He believes that growth will continue, as capitalism reinvents itself yet again, this time for the information age—though he admits that “flush toilets are way more important than Facebook.”

With that, the lecture concludes, and the lucky attendees weigh the expected utility of waiting in line to speak with the most influential living economist against the expected utility of beating the rush to the cava and jamón ibérico at the reception. The gears of the market keep turning.


  1. Lucas, Robert E. 2015. “Human Capital and Growth.” American Economic Review, 105(5): 85-88.
  2. Lucas, Robert E. 2009. “Trade and the Diffusion of the Industrial Revolution.” American Economic Journal: Macroeconomics, 1(1): 1-25.
  3. Lucas, Robert E. 2009. “Ideas and Growth.” Economica, Vol. 76, Issue 301: 1-19.
  4. Malthus, Thomas Robert. 1798. “An Essay on the Principle of Population.” Library of Economics and Liberty.
  5. Becker, Gary S. 1960. “An Economic Analysis of Fertility.” Demographic and Economic Change in Developed Countries. Princeton: Princeton University Press.

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