Alberto Russo

Reflections on modern macroeconomics: Can we travel along a safer road?☆

In this paper we sketch some reflections on the pitfalls and inconsistencies of the research program—currently dominant among the profession—aimed at providing microfoundations to macroeconomics along a Walrasian perspective. We argue that such a methodological approach constitutes an unsatisfactory answer to a well-posed research question, and that alternative promising routes have been long mapped out but only recently explored. In particular, we discuss a recent agent-based, truly non-Walrasian macroeconomic model, and we use it to envisage new challenges for future research.

Sectoral Imbalances and Long-run Crises

There has been a widespread presumption that the current economic crisis is a financial crisis, caused by the bursting of a credit bubble. Unjustified optimism about asset prices and associated risks (primarily in housing but also in financial industry equities and even in equities generally), accommodated by lax regulation, careless private lending and loose monetary policies, led to unsustainable levels of household and financial sector leverage. The inevitable collapse of the underlying asset prices then caused widespread bankruptcies, foreclosures, and impaired balance sheets among households, firms, and financial institutions. Combined with consequent large increases in the incremental risks of lending and investing, these balance sheet effects induced large declines in household spending, firm output and investment, and bank lending.1

A Stochastic Model of Wealth Accumulation with Class Division

In this paper we propose a stochastic model in which wealth accumulation depends on the role that agents play in the society: capitalists or workers. A random mechanism of class selection shapes the social structure of the economy based on wealth distribution dynamics. As a result, the society may evolve towards an unequal outcome with few rich and many poor individuals, even starting from perfect equality. We study the dynamic properties of the model by means of computer simulations. A maximum likelihood estimation procedure is applied to analyse the Pareto or power law tail of wealth distribution. We also provide a scenario analysis to explore the systems behaviour under alternative parameter settings.

Elements of Novelty, Known Mechanisms, and the Fundamental Causes of the Recent Crisis

This article briefly describes the evolution of the recent economic crisis based on different theories toward my own interpretation of it. The deregulation wave of the last decades has created new profit opportunities in various contexts — from labor flexibility to privatization and from financialization to globalization — so promoting a renewed process of capitalist accumulation after the stagflation of the 1970s. This has taken place at the cost of a wide-ranging increase in inequality and instability, thus bringing a cascade of crises, including the latest one of 2008.

FINANCIAL REGULATION AND ENDOGENOUS MACROECONOMIC CRISES

We explore the effects of banking regulation on financial stability and macroeconomic dynamics in an agent-based computational model. In particular, we study the minimum level of capital and the lending concentration towards a single counterpart. We show that an overly tight regulation is dangerous because it reduces credit availability. By contrast, overly loose constraints, associated with a high payout ratio, increase financial fragility that, in turn, damage the real economy. Simulation results support the introduction of regulatory rules aimed at assuring an adequate capitalization of banks, such as the Capital Conservation Buffer (Basel III reform).

Does Inequality Hamper Innovation and Growth

The paper builds upon the Agent Based-Stock Flow Consistent model presented in Caiani et al. (2015) to analyze the relationship between income and wealth inequality and economic development. For this sake, the original model has been amended under three main dimensions: first, the households sector has been subdivided into workmen, office workers, researchers, and executives which compete on segmented labor markets. Conversely, firms are now characterized by a hierarchical organization structure which determines, according to firms’ output levels, their demand for each type of workers. Second, in order to account for the impact of income and wealth distribution on consumption patterns, different households classes - also representing different income groups - have diversified average propensities to consume and save. Finally, the model now embeds technological change in an evolutionary flavor, affecting labor productivity evolution in the consumption sector through product innovation in the capital sector, where firms invest in R&D and produce differentiated vintages of machineries. The model is then calibrated using realistic values for both income and wealth distribution across different income groups, and their average propensities to consume. Results of the simulation experiments suggest that more progressive tax schemes and labor market policies aiming to increase low and middle workers’ coordination, and to support their wage levels, concur to foster economic development and to reduce inequality, though the latter seem to be more effective under both respects. The model thus provides some evidence in favor of a wage-led growth regime, where improvements of middle-low levels workers’ conditions create positive systemic effects, which eventually trickle up also to high income-profit earners households.

Economics with Heterogeneous Interacting Agents: A Practical Guide to Agent-Based Modeling

This book offers a practical guide to Agent Based economic modeling, adopting a learning by doing approach to help the reader master the fundamental tools needed to create and analyze Agent Based models. After providing them with a basic toolkit for Agent Based modeling, it present and discusses didactic models of real financial and economic systems in detail. While stressing the main features and advantages of the bottom-up perspective inherent to this approach, the book also highlights the logic and practical steps that characterize the model building procedure. A detailed description of the underlying codes, developed using RandC, is also provided. In addition, each didactic model is accompanied by exercises and applications designed to promote active learning on the part of the reader. Following the same approach, the book also presents several complementary tools required for the analysis and validation of the models, such as sensitivity experiments, calibration exercises, economic network and statistical distributions analysis. By the end of the book, the reader will have gained a deeper understanding of the Agent Based methodology and be prepared to use the fundamental techniques required to start developing their own economic models. Accordingly, Economics with Heterogeneous Interacting Agents will be of particular interest to graduate and postgraduate students, as well as to academic institutions and lecturers interested in including an overview of the AB approach to economic modeling in their courses.

Growing Inequality, Financial Fragility, and Macroeconomic Dynamics: An Agent Based Model

Our aim is to analyse the interplay between growing inequality and financial fragility in a complex macroeconomic system. In order to do this, we propose a macroeconomic microfounded framework with heterogeneous agents in which households, firms, and banks interact according to decentralised matching processes. The main result is that growing inequality leads to more macroeconomic volatility, increasing the likelihood of observing large unemployment crises.

Increasing Inequality and Financial Fragility in an An Agent Based Macroeconomic Model

The aim of this paper is to investigate the relationship between increasing inequality and financial fragility in an agent based macroeconomic model. We analyse the effects of a non-linear relationship between wealth and consumption on the evolution of the economic system. Preliminary results show that more inequality rises macroeconomic volatility, increasing the likelihood of observing large unemployment crises.

Complex dynamics and empirical evidence

Standard macroeconomics, based on a reductionist approach centered on the representative agent, is badly equipped to explain the empirical evidence where heterogeneity and industrial dynamics are the rule. In this paper we show that a simple agent-based model of heterogeneous financially fragile agents is able to replicate a large number of scaling type stylized facts with a remarkable degree of statistical precision.