John Weisweiler Bart Danon Myles Lavan (Sektionsleitung)

Modelling the Dynamics of Wealth in the Roman Empire

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Rome is of special interest for the trajectory of inequality in a world historical perspective. The rigorous enforcement of property rights by the Roman state provided a model and inspiration for later European régimes of inequality. And never again until the 19th century would single individuals be as wealthy as the richest Romans. Yet the evidence to reconstruct the evolution of inequality in the ancient world is fragile. For these reasons, Rome offers an excellent case study of how new methods may help us to interrogate accepted facts about pre-modern economies.

Only in some places and rare moments do we have data of actual wealth distributions. In the absence of good data, historians have often fallen back on intuitive inferences about the impact of various aspects of the legal, economic and social environment on inequality. But intuition is not always a good guide to the dynamics of complex systems.

In this panel, we will explore how computer-based modelling might help us to better understand the factors that affected the evolution of inequality in the Roman world.

Economists have shown that every economy has an equilibrium level of wealth inequality towards which it will move, in the absence of external shocks. We will explore the use of Agent-Based Modelling to simulate the impact of variation in different conditions (such as mortality levels or the inheritance regime) on this equilibrium level. By modelling and comparing different scenarios, we can investigate the effect of these conditions on equilibrium inequality.

We simulate the impact of three factors on wealth distribution. First, we examine to what extent different mortality regimes would have affected the equilibrium level of wealth inequality. Second, we test the widespread assumption whether partible inheritance produced lower equilibrium levels of inequality than primogeniture. Finally, we explore the impact of munificence on the concentration of wealth and levels of socio-economic mobility.

Bart Danon (Groningen) Myles Lavan (St. Andrews) John Weisweiler (München)
Agent-Based Modeling and Roman Inequality

Since the financial crisis, there has been resurgence of interest in economic inequality in the Roman empire. Most notably, in his The Great Leveler (2017), Walter Scheidel has argued that never again until the modern period was wealth as unequally distributed as in the Mediterranean world of the first four centuries CE. Yet while ancient historians broadly agree that the Roman world witnessed a trend towards disequalization, we do not yet fully understand the reasons for this development. The opening paper of this panel examines how computer modeling might help to get a better understanding of the respective weight of different factors in promoting wealth concentration.


Bart Danon (Groningen)
Demography and the Dynamics of Wealth

How does the mortality regime in a society affect the level of wealth inequality? Thomas Piketty and Gabriel Zucman (2015) argue that multiplicative random shocks (for instance the level of mortality or the number of surviving children) have a profound impact on the shape of the wealth distribution. High levels of mortality imply high rates of wealth transmission through inheritance. When wealth is transmitted there is always the risk of estate fragmentation but also opportunities for the concentration of wealth. In this paper, I will use an Agent-Based Model to assess the impact of different (premodern) mortality regimes on the expected level of inequality.

Myles Lavan (St. Andrews)
Partible Inheritance and the Dynamics of Wealth

This paper explores the impact of partible inheritance on the dynamics of the wealth distribution in the Roman empire. Keith Hopkins’s classic Death and Renewal (1983) drew attention to the norm of equipartition in the transmission of property in Roman society and explored its implications for the ruling class’ capacity to reproduce itself. This paper extends the focus to consider how partible inheritance would have impacted the shape of the wealth distribution in comparison to societies with a norm of primogeniture. The paper explores the use of simulation based on Agent-Based Modelling to estimate the likely direction and magnitude of these effects in the absence of good data on the wealth distribution itself.

John Weisweiler (München)
Return on Capital and the Dynamics of Wealth

This paper explores how differing rates of return on capital may have affected levels of inequality in the Roman empire. In his Le capital au XXIe siècle (2013) Thomas Piketty shows that across history capital owners could expect to derive an average return of about 5-6 per cent on their investments. At the same time, he makes the case that today returns rise in line with overall wealth – the ultra-rich tend to receive higher average returns than the merely wealthy. By contrast, the ancient historian Jean-Michel Carrié argues that in antiquity the relationship between return on capital and overall wealth was more complex; for instance, household firms may have been more profitable than medium-scale enterprises. This paper simulates how either effect would have influenced the Roman wealth distribution.


Sitta von Reden (Freiburg)
The Quantitative Turn in Ancient Economic History

This paper offers a response to the arguments of the other panelists. It situates agent-based modeling in the broader context of recent scholarship on the Roman economy. What are the pitfalls, what are the opportunities in employing computer simulations to better understand a period for which documentary evidence is only sparsely preserved?

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