# Thomas Piketty's Circle and the School of Inequality

Benoît Walraevens, Matthieu Pourieux

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# Thomas Piketty's Circle and the School of Inequality

Benoît
WALRAEVENS

Université de Caen Normandie,
CNRS, CREM UMR 6211, F-14000
Caen, France :
benoit.walraevens@unicaen.fr

Matthieu
POURIEUX

Univ Rennes, CNRS, CREM-
UMR6211, F-35000 Rennes, France :
matthieu.pourieux@univ-rennes.fr

01/2026
# Thomas Piketty's Circle and the School of Inequality<fnref n="1" />

Benoît Walraevens<fnref n="2" />, Matthieu Pourieux<fnref n="3" />

*Preliminary draft – Please do not quote without permission<fnref n="4" />*

**Abstract:** This paper analyzes the emergence of a new school of economic thought, termed the “inequality school”, which has successfully placed the distributional issue back at the heart of economic analysis and public debate. Led by Thomas Piketty, the school is a collective movement founded on the emerging international research network on inequality working at or collaborating with the *World Inequality Lab (WIL)*. We present first the origins and foundations of this school as well as its members by distinguishing, through a bibliometric analysis, an “inner circle”, the originators and leaders of the school, made up of Piketty, Saez, Alvaredo, Zucman and Chancel, and a “wider circle”, made up of the collaborators and contributors of the ever-growing international network of the *WIL*. Then we identify its characteristics in terms of topic, methodology, values, and policy proposals, and highlight its contributions to economic science. Finally, we present the view of economics that members of the school share as a social, political, historical, and moral science and its democratic role.

**Key words:** Inequality; School of Thought; Thomas Piketty; World Inequality Lab; Taxation

**JEL classifications:** B2; B30; H2

## Introduction:

Undeniably, there is a return of and growing interest in the issue of inequality in economics in the 21st century, and especially since the 2010s<fnref n="5" /> (in the aftermath of the 2008 financial crisis),

<footnote n="1">¹ Previous versions of this paper were presented at the ESHET conference in Padova in May 2022, at the Cournot Seminar in Strasbourg in February 2023, at the Gide conference in June 2023, and at the ESPOL seminar in Lille in January 2025. We thank the participants at these seminars and conferences for useful comments and suggestions. We also greatly benefitted from exchanges with Alain Trannoy, Branko Milanovic, Marc Fleurbaey, Jean-François Laslier, Claude Diebolt, Jimena-Hurtado Prieto and Thomas Piketty.</footnote>

<footnote n="2">² Université de Caen Normandie, CNRS, CREM UMR 6211, F-14000 Caen, France: benoit.walraevens@unicaen.fr</footnote>

<footnote n="3">³ Univ Rennes, CNRS, CREM-UMR6211, F-35000 Rennes, France: matthieu.pourieux@univ-rennes.fr</footnote>

<footnote n="4">⁴ For the purpose of Open Access, a CC-BY public copyright licence has been applied by the authors to the present document and will be applied to all subsequent versions up to the Author Accepted Manuscript arising from this submission.</footnote>

<footnote n="5">⁵ In a general and simplified way, the growing and accelerating interest in the issue of economic inequality in the 21st century is visible through a quick search on Google ngram viewer of the terms “economic inequality” (+ “English” and “case-sensitive”). In 1980, it represented 0,0000086992% of words in Google Books, in 2000, 0,0000183482%, in 2010, 0,0000288194%, in 2020, 0,0000658523%, in 2022, 0,0000673711%.</footnote>
after a long period of oblivion. In his April 1996 Presidential Address to the Royal Economic Society, Anthony Atkinson was already calling for “bringing income distribution in from the cold” and for the “re-incorporation of income distribution into the main body of economic analysis” (Atkinson, 1997, p. 297). One can think now that his call has been heard.

Many reasons can be advanced to explain why the issue of economic inequality has long been neglected or marginalized in economics.<fnref n="6" /> Perhaps the most important one is a strong belief in the famous inverted-U shaped Kuznets curve, predicting a decrease of inequality in the long run with economic development, after an initial phase of increase. This “prediction” has been increasingly refuted by the accumulated data showing a rising trend of within-country inequality since the 1980s all over the world, though in different magnitudes.<fnref n="7" /> Other reasons include the widespread idea among economists that there is a necessary trade-off between equity and efficiency (see Okun, [2015]1977), some belief in trickle-down economics, or the view that economics should focus on the reduction and eradication of (absolute) poverty rather than inequality *per se*. The dominance of neoclassical economics with its three theoretical pillars: marginal productivity theory, utility theory, and Pareto optimality, might also be seen as possible causes (see Cook, 2019).

That said, a close look at the history of economic thought immediately shows that our discipline has not always neglected questions of income and wealth distribution, far from it (see Sandmo, 2000; Milanovic, 2023⁸). Indeed, the distribution of income or wealth between social classes was a fundamental issue in classical political economy from Smith,<fnref n="9" /> Ricardo<fnref n="10" /> and Malthus to Marx through Sismondi and the Ricardian socialists, but they had no access to reliable and

<footnote n="6">⁶ For a very rich analysis of the marginalization of inequality studies specifically during the Cold War, see Milanovic (2023, chap 7, «The Long Eclipse of Inequality Studies», pp. 217-86.</footnote>

<footnote n="7">⁷ It is important to remember that Kuznets was aware of the limitations of his “prediction” of a lowering of inequality in the long run with economic development: “In concluding this paper, I am acutely conscious of the meagerness of reliable information presented. The paper is perhaps 5 per cent empirical information and 95 per cent speculation, some of it possibly tainted by wishful thinking” (Kuznets, 1955, p. 26) For an historical analysis of the changing significance of Kuznets’s “law”, see Moran (2005).</footnote>

<footnote n="8">⁸ On the history of the economic theories of distribution and inequality, see Sandmo (2015). See also Milanovic (2023), whose book focuses on what he sees as the main “integrative” studies of income distribution in the history of economic thought, that is, “visions of inequality” mixing a narrative, theory and empirics.</footnote>

<footnote n="9">⁹ On Smith’s views about economic inequality, see Walraevens (2021).</footnote>

<footnote n="10">¹⁰ In the Preface to his *Principles of Political Economy and Taxation* Ricardo famously claimed that “The produce of the earth—all that is derived from its surface by the united application of labour, machinery, and capital, is divided among three classes of the community; namely, the proprietor of the land, the owner of the stock or capital necessary for its cultivation, and the labourers by whose industry it is cultivated. But in different stages of society, the proportions of the whole produce of the earth which will be allotted to each of these classes, under the names of rent, profit, and wages, will be essentially different; depending mainly on the actual fertility of the soil, on the accumulation of capital and population, and on the skill, ingenuity, and instruments employed in agriculture. To determine the laws which regulate this distribution, is the principal problem in Political Economy.”</footnote>
extensive data series about the *individual* repartition of income and wealth, as Piketty
underlined (see Piketty, 2014, introduction, pp. 3-11). The most interesting source of
information about socio-economic inequality which existed at that time to estimate inequality
from the end of the 17th century to the 19th century were UK's "social tables" (see Lindert and
Williamson, 1982; and more recently Allen, 2019). Whatever the case, classical economists
adopted a different view about inequality. They were mainly interested in *factorial* or *functional*
income distribution, as were after them the neo-Keynesians, that is they focused on the
inequality between labour, capital, and land incomes, rather than on *individual* income
distribution, studying the evolution of profit, wage and rent when wealth increases, stagnates
or declines. Recent works by Ranaldi seem to reconcile the classical economists' view of
inequality with today's individual view, by introducing the concept of "compositional"
inequality, studying how the (de)composition of income in two sources, such as capital and
labor income, varies across the income distribution (see Ranaldi, 2022, 2025).

In 2004, Robert Lucas famously claimed that “Of the tendencies that are harmful to sound economics, the most seductive, and in my opinion the most poisonous, is to focus on questions of distribution”. But inside academic economics now, this point of view seems more and more rare (Atkinson and Bourguignon, 2015, p. xvii). Indeed, there has been a real and growing interest for inequality in economics, at least since the beginning of the 21st century, as Piketty and others noted (see Piketty, 2014, introduction, pp. 15-16; see also Milanovic, 2023, pp. 287-88). In this trend, it is impossible not to mention the huge success of the latter’s works, and especially of his book *Capital in the 21st Century* first published in French in 2013, then translated in dozens of languages and sold millions of copies worldwide. This book has obviously played a key role in putting the topic of (rising) inequalities of revenue and wealth at the forefront of economic discourse and public debate all over the globe (see also Stiglitz, 2012; Bourguignon, 2012; Milanovic, 2016; and several *OECD, IMF and World Bank* works on inequality and on the need for a more inclusive growth during this decade).

But Piketty’s works, as he himself emphasizes (see Piketty, 2014, acknowledgments), have also
benefitted from the contributions of many different scholars which we argue take part in an
emerging and growing research network working on economic and social inequality. In fact,
the thesis we are defending in this paper is even that a new school of economic thought is
emerging, which we will call the “inequality school”. That is, a group of economic scholars
which aims at “Putting the Distributional Question Back at the Heart of Economic Analysis”
(Piketty, 2014, p. 15), as advocated by Atkinson. We see the school’s main institutional
framework in the World Inequality Lab (WIL), home of the World Inequality Database (WID) which succeeded to the World Top Incomes Database, created in 2011 (more on this later), and its leading figure and epicenter in Thomas Piketty, an economist who started developing an historical and political economy of inequality at the turn of the 21st Century, and who reached the status of an international intellectual with the phenomenal success of *Capital in the 21st Century* (see Brissaud and Chahsiche, 2017). The aim of this paper is to study this new economic school, the inequality school, founded on the emerging and growing international research network on inequality (henceforth IRNOI) working at or collaborating with the WIL. We will present the origins and foundations of this school, its characteristics and its contributions to economics.

But how to characterize in a general way a “school of thought”<fnref n="11" />? Following Negru (2013), one can define it as being made of two main components: (i) a *system of thought* and (ii) *members practitioners*. A system of thought comprises all or part of the following features: an ontology and epistemology, a methodology, an ethics and axiology, and an ideology (Negru, 2013, pp. 987-88). And it presupposes two elements: some *coherence* and homogeneity on these grounds, but also some *distinctiveness* with regard to other schools or systems of thought.<fnref n="12" /> As she rightly argues, “a school of thought is defined through identity and similarity on the one hand, and through difference and opposition on the other” (Negru, 2013, p. 989). In other words, schools of (economic) thought are “epistemic communities” (Lari, 2021, p. 3). Thus, we will try to unveil what makes the identity of the international community of scholars working on the global history of economic inequality at the WIL, their characteristics as well as their contributions to economic science.

The paper will be organized as follows. Section I will quickly present the history of the emergence and development of the IRNOI of the WIL, identifying its originators, its leader(s), its members, and its main precursors and inspirators. Section II defines the main characteristics of this group of economic scholars, emphasizing its very strong identity and unity in terms of topic, methodology, explanations of (rising) inequality, and policy proposals. Section III presents their specific view of economics as a historical, political, social, and moral science.

<footnote n="11">¹¹ Though widely used in social science, and especially in economics, for characterizing scientific networks, the notion of “school” is not uncontroversial and alternative concepts have been developed such as “nebula” (see Topalov, 1999), “creative community” (see Forget and Goodwin, 2011) or “research network”. Classical studies on the attributes of research schools in science are Morell (1972) and Geison (1981), formalizing the latter.</footnote>

<footnote n="12">¹² In this paper, we will focus mainly on the “coherence” of the system of thought of the inequality school rather than on its distinctiveness, but of course a comparison with other schools might be welcome to show it.</footnote>
Lastly, a short conclusion recalls the main theses of the paper and the context of emergence of
the inequality school, as well as some reasons for its success, both inside and outside academia.

1) On the origin, birth and development of the IRNOI of the WIL

We begin with the “social dimension” (Lari, 2021) of the alleged “inequality school”, i.e with
the identification of its main figures and more generally of its “members practitioners” (Negru,
2013). To do this, we are going to try to retrace the history of the International Research
Network On Inequality (IRNOI) of the WIL, studying its origin, birth and development to the
present day.

1.1

Let’s start with the one we consider as the founder and leader of the IRNOI of the WIL, the
now well-known French economist Thomas Piketty. We think that he is the *epicenter* of the
IRNOI, particularly with his network of PhD students and with his co-written or coedited papers
and books with many researchers, but also importantly because he provided the IRNOI of the
WIL with its *intellectual matrix*. In the early years of his academic career, Piketty produced
*theoretical* and normative works on inequality, social mobility, taxation and redistribution, of
which he was unsatisfied. After having defended his PhD thesis in 1993, at the age of 22, at the
*EHESS (Ecole des Hautes Etudes en Sciences Sociales, the French School for Advanced Studies
in the Social Sciences)* and at the *London School of Economics*, he was recruited by Peter
Temin, a famous specialist of economic history, as an Assistant Professor of Economics at the
*Massachusetts Institute of Technology*, the same year as Daron Acemoglu (see Temin, 2014).
Yet, he chose after only 2 years to leave America because he wanted to come back in France
and to find a position at the *EHESS*, in order to focus on a more empirical and historical analysis
of economic inequality, and more generally to develop a “social science” view of economics
(see Piketty and al 2020, p. 2). Piketty wanted to place his work within a tradition of economic
and social history dating back to the French Annales school of history, towards which he often
expressed his admiration and debt, and still infusing his most recent works (see Piketty, 2021,
pp. 138; Piketty, 2023, p. 13; Cage and Piketty, 2023, introduction).<fnref n="13" />

<footnote n="13">¹³ Well before Piketty, the *Annales school* had promoted an economic and social history at the heart of social sciences. The journal of the school was called *Annales d'histoire économique et sociale* when it was created in 1929 and up until 1938. After multiple changes, it is called today, *Annales. Histoire, sciences sociales*. The school was focused on long-term historical and quantitative analysis and on topical issues, as is Piketty. The journal has published special issues on Piketty's books *Capital in the 21st Century* and *Capital and Ideology*. It is noteworthy</footnote>
He first spent 5 years as a *CNRS* (Centre National de la Recherche Scientifique) researcher at *CEPREMAP*, and then he joined the *EHESS* as a Director of Studies in 2000, holding a chair on "the political economy of inequality". Piketty's return in France in the second half of the 1990's thus marks the beginning of the "historical turn" of his career, encouraged by his first wife, Nathalie Moine, a *CNRS* researcher in history (see Piketty, 2001, preface). In fact, he had always been more interested in history, but he did some theory and modelling because, from his own admission, "that's what [he] knew how to do" (Piketty and al, 2020, p. 2).

Influenced by the long tradition of economic and social history dating back to the Annales school, he began working alone on his new research program on the historical dynamics of inequality in 1998 (see Piketty, 2014, acknowledgments and introduction), whose first major output was his 2001 book on high incomes in France in the 20th Century (Piketty, 2001) and whose culmination point was the publication of his worldwide best-seller, *Capital in the 21st Century* (Piketty, 2014). In recent years, and especially in *Capital and Ideology* (Piketty, 2019, 2020) and subsequent works (such as *A Brief History of Equality*), he seems to have switched towards a more "global", comprehensive and transdisciplinary analysis of the history of inequality in the modern era, studying its economic, social, political, and ideological dimensions. Piketty made important contributions to the *empirical* analysis of economic inequality, with his focus on the top of the distribution, his (very) long-term series, and a massive use of fiscal data. He also tried to contribute to the *theory* of income distribution. As is well-known now, in *Capital in the 21st Century* Piketty defends the view that usually r > g, or the idea that capitalism left to itself maintains a high rate of return to capital superior to the (average) growth rate of the economy, leading to an inexorable rise of inequality, which can only be interrupted or reversed by external factors like wars, hyperinflation, and political decisions (see Milanovic, 2023, pp. 291-92). Hence its emphasis on the politics of redistribution and on ideologies that either justify or try to reduce inequality. In Milanovic's words, "For the first time since Kuznets, economists were presented with an alternative theory of the forces that determine income distribution." (ibid., p. 292).

But let's go back to the publication of Piketty's first book on economic inequality in 2001, which was a pivotal moment in the history of the IRNOI which will lead to the creation of the

<footnote>that Lucien Febvre, one of the founders of the journal and the school, set up the 6th section of the *Ecole Pratique des Hautes Etudes (EPHE)*, which later became the *EHESS*, where Piketty is now director of studies, and which has been chaired by many historians of the *Annales school*. See Benest (2024a). In another paper, Benest interestingly shows that the sixth section of *EPHE* was initially meant to be a training place for economists for postwar reconstruction and dominated by them before Annales historians took center stage (see Benest, 2024b).</footnote>
WIL. In a way, it can be seen as its starting point. Indeed, immediately after the publication of this book, Piketty received the support of two people who will have a crucial role in the emergence of the IRNOI of the WIL, namely Emmanuel Saez and Anthony Atkinson. Piketty knew both for a long time. He had first met the latter in 1991 at the LSE (London School of Economics and Political Science), during his PhD<fnref n="14" /> and Atkinson was often at the DELTA in Paris when Piketty was working on his PhD thesis under the supervision of Roger Guesnerie. The DELTA research laboratory of the Ecole normale supérieure (ENS) was founded and directed by François Bourguignon<fnref n="15" /> (alternatively with Guesnerie), a renowned specialist of poverty and inequality and long-time collaborator of Atkinson, and it is the ancestor of the Paris School of Economics. Atkinson got a Doctor Honoris Causa of the ENS in 1995. He was a member of section 37 (Economics and Management) of the CNRS when Piketty was recruited after his return from MIT and then an external reviewer of Piketty’s application at the EHESS. More generally, Atkinson was arguably the most important public economist of the 20th Century and the greatest economic thinker on inequality since Kuznets (Kleven and Luttmer, 2018, p. 1). He was both a precursor, an inspirator (see Kleven and Luttmer 2018, p. 1), and a mentor for Piketty and for the members of the IRNOI of the WIL,<fnref n="16" /> of which he was actually part of in the final years of his life.<fnref n="17" />

During his career, Atkinson has made huge contributions to the study of economic inequality (not to mention his seminal works on poverty), both empirically and theoretically speaking, as attest the 3 special issues of the *Journal of Economic Inequality* devoted to him just after his death on January 1, 2017¹⁸ (see also Sandmo, 2017; Aaberg et al., 2017). One can think in particular of his famous index to measure inequality (Atkinson, 1970), of his early works on

<footnote n="14">¹⁴ Piketty was involved in a European Doctoral Programme in Economics, that’s why he spent his PhD at both the EHESS and the LSE.</footnote>

<footnote n="15">¹⁵ Bourguignon was a Director of Studies at the EHESS. He is now Emeritus Professor at the Paris School of Economics, that he directed from 2007 to 2013, and a WID fellow.</footnote>

<footnote n="16">¹⁶ See the acknowledgments in Piketty (2014, p. viii and p. 18), Piketty’s and the WID’s tributes to him after he passed away (https://www.lemonde.fr/blog/piketty/2017/01/03/disparition-de-anthony-b-atkinson/; https://wid.world/news-article/tonys-passing-wid-world-mourning-2/), as well as Alvaredo and Garcia Penalosa 2018. So, it comes as no surprise that they dedicated to Atkinson the first *World Inequality Report*, published in 2018.</footnote>

<footnote n="17">¹⁷ It is interesting to note that Atkinson also founded in 1972, and directed for years, the *Journal of Public Economics*, the leading journal of the field of public economics, of which Piketty was a co-editor from 1996 to 2012, and Saez a co-editor from 2003 to 2006 and an editor from 2006 to 2010.</footnote>

<footnote n="18">¹⁸ Note that the journal was launched in 2003. The first issue of the journal, published in April of the same year, included a paper from Atkinson and a foreword by Amartya Sen. As to the special issues in honor of Atkinson, the first one was published in December 2017, and was about “Tax-benefit systems, Income Distribution and Welfare Analysis”. The 2nd one, published in 2018, was on “Top incomes, wealth and inheritance”, and introduced by Alvaredo and Garcia-Penalosa. Finally, the 3rd one published in March 2019 dealt with “Multidimensional analysis and mobility”.</footnote>
optimal taxation (Atkinson and Stiglitz, 1972, 1976; see also Atkinson, 1973 in which he is the first to integrate so-called “Rawlsian” maximin social welfare functions into optimal taxation theory<fnref n="19" />) and most importantly for our purpose, of his first empirical and theoretical studies on income and wealth inequality in the UK in the early 1970s (Atkinson, 1971, 1972; Atkinson and Harrison, 1974, 1978). Atkinson was also instrumental in creating new and valuable data sources such as the *Luxembourg Income Study* in the 1990s, which resulted in an important collective book presenting cross-country inequality comparisons in the *OECD* (see Atkinson & al, 1995). For Piketty, “Together with Simon Kuznets, Atkinson single-handedly originated a new discipline within the social sciences and political economy: the study of the historical trends of the distribution of income and wealth” (Piketty, 2018, p. 41). Piketty and the IRNOI working at and collaborating with the WIL are the continuators and developers of this “new discipline” and empirical tradition of research on inequality.

Piketty also knew Saez since the early 1990's, when they were both students at the *ENS* in Paris. In 2001 Saez was already a promising public economist. He had defended his PhD in Economics at *MIT* in 1999 and was Assistant Professor in Economics at *Harvard University*. So, both Saez and Atkinson encouraged and helped Piketty to extend the study of the history of inequality to other countries (respectively on the USA and Great-Britain first) in the early years of the 21st Century (Piketty, 2014, p. 17). The first paper that Piketty and Saez wrote together was on inequality in the USA in the 20th Century (Piketty and Saez, 2003). Published in 2003, and it is up to this date Piketty's second most quoted work (after Piketty, 2014) and Saez's most quoted one, according to Google scholar citations, with 5763 quotes (as of August 28, 2025). Saez also quickly produced empirical works on inequality in Canada and Japan, and on inequality in Switzerland with Piketty, works which were published in two important collective books coedited by Atkinson and Piketty (with several contributions from them) in 2007 and 2010 on inequality in different countries (Atkinson and Piketty, 2007, 2010). It is noteworthy that the 2010 volume contains several chapters by Facundo Alvaredo, who had defended his PhD at the *Paris School of Economics (PSE)* under the supervision of Piketty in 2008. Spontaneously, with the two volumes a network of researchers studying top incomes was emerging (see the preface to Atkinson and Piketty, 2010), and it will be structured shortly afterwards with the creation in January 2011 of the *World Top Incomes Database* (WTID). At that time, another key protagonist of the emergence and development of the IRNOI is doing his

<footnote n="19">¹⁹ For more details on the integration of Rawls's theory of justice in nascent optimal taxation theory, see Walraevens (2023).</footnote>
PhD at *PSE* under the supervision of Piketty, Gabriel Zucman, who will defend it in 2013. His research was focused in particular on issues of tax evasion, a much-neglected topic in economics (see Zucman, 2013²⁰).

The aim of the WTID was to provide convenient and free access to all the existing series. The international network of researchers involved in the project quickly grew to reach more than a hundred persons, so that the WTID expanded to include series on income inequality for dozens of countries, spanning over most of the 20th and early 21st centuries. The key novelty was to combine fiscal, survey and national accounts data in a systematic manner.

Then in September 2013 was published by Le Seuil, a Parisian editor, the first, original edition of Piketty's magnum opus and soon to be worldwide bestseller, *Le capital au XXIe siècle*, translated in English in 2014 and then in dozens of languages. It sold millions of copies around the world and was adapted as a documentary in 2020 (Pemberton and Piketty, 2020). This book made Piketty famous well beyond academic circles, having a deep impact on public debate in the aftermath of the 2007-2008 financial crisis. In the acknowledgments of the book, Piketty underlines that “a great part” of the 15 years of research (1998-2015) he spent on studying the historical dynamics of incomes and wealth, and on which the book is built, “have been carried out in collaboration” (Piketty, 2013, p. 9). Piketty emphasizes the seminal role played by Atkinson's and Saez's early support of and help on his research program, the fruitful exchanges he had with several doctoral students and young researchers, and the importance of the WTID, massively used in the book (ibid, p. 10). More specifically, Piketty thanks Alvaredo for his work on the database, and Zucman for his work on the wealth/income ratios in rich countries (ibid, p. 11), that the latter had developed in his PhD dissertation (Saez, 2024, p. 230).

Two years later, in 2015, was created the *World Inequality Lab* (WIL), the research centre hosting the open access database and soon several other projects. The WIL was first institutionally linked both to the *Paris School of Economics (PSE)*, that Piketty founded with Daniel Cohen in 2006 and of which he was the first director, and to the *University of California, Berkeley* where Saez was a Professor of Economics and was joined by Zucman in 2015 when the latter was recruited as Assistant Professor (after 2 years as Assistant Professor at the *LSE* in London). The WIL and the WID were first co-directed by Facundo Alvaredo, Thomas Piketty,

<footnote n="20">²⁰ The Preface of the book was written by Thomas Piketty. Zucman had completed a Master's Degree at *PSE* in 2008 with a dissertation, supervised by Piketty, investigating whether the rich fled the French Wealth Tax (Saez, 2024, p. 228). Then he spent some time in a financial firm, where he was observing international capital flows and became interested in tax evasion. He thus decided to come back in academia to study this issue (ibid.).</footnote>
Emmanuel Saez and Gabriel Zucman. Still in 2015, the WTID became the *World Wealth and Income Database* (the World Inequality Database), before being renamed in 2017 *WID.world*, the biggest public database on inequality in the world. The change of the name of the database from WTID to WID was made in order to express the extended scope and ambition of the database and the new emphasis on both wealth and income. That same year, Lucas Chancel, another PhD student of Piketty and a specialist of climate inequality, also became co-director of the WIL. Piketty, Saez, Alvaredo, Zucman and Chancel are still co-directors of the WIL and WID, and the main public figures of the WIL, though lately Saez and Zucman have switched to a position of “scientific” co-directors. This slight change is undoubtedly due to the fact that the latter is very involved too in another related research unit working on inequality. Indeed, he has launched and directed since June 2021 the *European Union Tax Observatory* (EUTO), an independent and growing research laboratory also hosted at PSE, promoting innovative research on taxation and new concrete proposals to address the tax and inequality challenges of the 21st century. After having spent years alongside Saez at the University of California, Berkeley, Zucman is back on his home soil since 2023 as a Professor of Economics at the ENS (where he had been a student, like Piketty and Saez before him) and PSE. A pioneer in the study of tax evasion, Zucman coedited the first *Global Tax Evasion Report 2024* and developed with the EUTO an online database on tax evasion, the “Atlas of the Offshore World”.<fnref n="21" /> He also took the direction of the *PSE Stone Center on Global Wealth Inequality Dynamics*, created in 2025, a cooperation between PSE and the James M. and Cathleen D. Stone Foundation which has funded wealth inequality projects in several institutions in North America<fnref n="22" /> and Europe.

Alongside Saez's and Zucman's partial distancing from the direction of the lab, a new co-director of WIL and WID was appointed in November 2024, Rowaida Moshrif, a PhD student of Piketty. In fact, many students from Piketty have played and still play a fundamental role in the WIL. Although they never became co-directors of the WIL and WID, many of them have held or still hold key positions in the lab as thematic or regional coordinators, who are responsible for updating the database (see in particular Gethin, Martinez-Toledano, Nievas, Sodano), while others are or were researchers or fellows (Nokovmet, Munoz...). Interestingly, Piketty's former PhD students and co-directors of the WIL (Alvaredo, Chancel, Zucman) have now their own PhD students working with the WIL (see Fisher-Post, Bauluz, Bomare, Bothe,

<footnote n="21">²¹ https://atlas-offshore.world/</footnote>

<footnote n="22">²² Emmanuel Saez is currently director of the *Stone Center on Wealth and Income Inequality* at the *University of California, Berkeley*.</footnote>
Mohren...), perpetuating and extending the legacy of the originator and leader of the IRNOI, Thomas Piketty, working for or collaborating with the WIL.

Since its launch in 2015, the WIL has never stopped growing over the years. Now hosted solely by PSE, it is composed in 2025 of about forty people with status of co-directors, thematic and regional coordinators, research fellows, research assistants, or staff.<fnref n="23" /> In our view, they constitute the heart of the inequality school. The WID is a more extended and truly global community of researchers. It includes the same co-directors and coordinators than the WIL but also now more than 200 collaborators around the world with a status of WID “fellows”, defined as “all researchers who have contributed to the development of the database, either through the production of data series or through methodological contributions or the publication of working papers and technical notes.”<fnref n="24" /> The number of WID fellows is constantly growing (there are twice more since 2018) and one can find among them several current and past PhD students and collaborators of Piketty like Landais<fnref n="25" />, Goupille-Lebret and Novokmet. The boundary between members of the WIL and WID fellows is porous and evolving with people’s academic career.

The WIL is thus still the home of the WID, but also of a growing number of additional projects related to the study of inequality mixing research projects, data platforms and visualization tools, such as the project on social inequality and political cleavages, a “global wealth tax simulator”, an “inequality transparency index” for each country, which is complementary to Tax Justice Network’s “Financial Secrecy Index” (see WIR 2022, p. 163, note 11), as well as specific projects on gender inequality and carbon inequality.

The WIL has also launched its own working paper series in 2014²⁶ and it organizes a regular seminar open to the public, the “Debates on Equality”, discussing recent books in social sciences, an important tool in their willingness to address people outside academic economics. Recent additions to the ever-growing list of projects hosted by the WIL include too Cage and Piketty’s research on elections and social inequalities in France since the French Revolution,

<footnote n="23">23 See https://inequalitylab.world/en/team/</footnote>

<footnote n="24">²⁴ See: WID Fellows - World Inequality Lab (last consulted on August 28, 2025).</footnote>

<footnote n="25">²⁵ Camille Landais made his PhD under the supervision of Piketty, getting it in 2008. He is now Professor of Economics at the LSE, and has been President of the French *Conseil d'analyse économique (Council of Economic Analysis)*, placed under the authority of the Prime Minister, whose mission is to shed light on the government's economic choices, and to which Atkinson and Piketty have been part of. Landais published a book with Saez and Piketty in 2011 calling for a fiscal revolution in France and a recent and important note on the reform of inheritance for this *Council* (see Dherbécourt & al, 2021). He is also in the Advisory Board of Zucman's *EUTO*.</footnote>

<footnote n="26">²⁶ See https://wid.world/fr/publications-wid/#library-working-papers</footnote>
and the “Missing Profits” platform on tax evasion. The latest projects of the WIL are the launch
in 2025 of a « Global Inequality Research Award », whose first laureate was Bina Agarwal, and
an ambitious “Global Justice Project”, whose aim is “to provide a platform to stimulate
research, policymaking, and citizen engagement to shape a fairer, more democratic and
sustainable 21st century.”<fnref n="27" /> Combining the data from the WID “with global input-output tables,
environmental accounts, labour force surveys and other sources,” the latter explores “what a
just distribution of socio-economic and environmental resources could look like at the global
level from 2025 to 2100 – both between and within countries – in a way that is compatible with
planetary boundaries.” The project “builds on the analysis and proposals set out in Thomas
Piketty’s *A Brief History of Equality*, extending them into a broader and more comprehensive
global framework.” (ibid) It is meant to provide “global convergence” scenarios founded on
two goals: socio-economic inequality and planetary habitability. The first working papers of
the project have been published in 2025 (see Bothe & al, 2025; Nievas and Piketty, 2025),
together with a new data platform, the “World Historical Balance of Payments Database”,<fnref n="28" /> and
its main results will be collected in 2026 in a *Global Justice Report*.

In fact, the WIL publishes every four years a *World Inequality Report*. The first one,
coordinated by Alvaredo, Chancel, Piketty, Saez and Zucman, with Chancel as general
coordinator, was published in 2018 while the second one, coordinated by Chancel, Piketty, Saez
and Zucman, with Chancel as lead author (and Rowaida Moshrif as data coordinator), was
published in 2022. The latest one, the 2026 edition, edited by Lucas Chancel, Ricardo Gómez-
Carrera, Rowaida Moshrif, and Thomas Piketty, has been published on December 10, 2025.
Additionally, the WIL launched in 2023 its first *Climate Inequality Report*, written and edited
by Lucas Chancel, Philipp Bothe, a PhD student of Chancel, and Tancrède Voituriez. A new
one, edited by Lucas Chancel and Cornelia Morhen, was published in October 2025. These
reports are important tools in the strategy of communication of the WIL to participate in and
have some influence on public debate and on policy-making. While the first report focused on
the inequality of consumption-based emissions, the latest one estimates the carbon footprint of
private capital ownership.

1.2 The “inner circle” and the “wider circle”

<footnote n="27">²⁷ https://inequalitylab.world/en/global-justice-project/</footnote>

<footnote n="28">²⁸ https://wbop.world/</footnote>
Now, among the members of the IRNOI of the WIL we would like to make a distinction between two groups: the “inner circle” and the “wider circle”. This distinction is based both on an analysis of academic and institutional links (which derives from the above history of the IRNOI of the WIL) and on a quantitative study of scientific links through co-authorship and citations.

First, the inner circle is composed of Piketty, and of his closest collaborators. Piketty might be considered as the natural leader of this research network on inequality, and of the inequality school associated with it, for many reasons. He is the originator of the research program on the history and political economy of inequality at the end of the 20th century and the most famous member of the IRNOI of the WIL thanks to the huge success of his book *Capital in the 21st Century*, which has made the WIL’s work known worldwide and far beyond academic circles. He has been quite instrumental and a leader in several projects of the WIL, such as of course the WID but also the projects on voting (see the projects “Political cleavages and social inequalities” and “Elections and social inequalities in France 1789-2022”), on Europe, on the methodology of “Distributional National Accounts” (see below section 2.2<sup>29</sup>) and on “Global Justice”. Inside the inner circle, we will also include those with whom Piketty wrote the most and who played a key role in the emergence and development of the WIL, and who co-direct(ed) it: Saez, Alvaredo, Zucman and Chancel, who is now also Associate Professor in Economics at *Sciences Po Paris*. Indeed, an analysis of co-authorship and citation links between all these authors reveals that they are particularly connected to one another. To run such an analysis, we extract bibliometric information on research publications (articles, books, book chapters and reports) using OpenAlex APIs (Priem et al., 2022).<sup>30</sup> Then, we identify for each member of the inner circle the number of publications that he co-wrote with the other members and the share it represents within all his co-authored publications. In addition, the database connects each publication to a list of publications which it refers to (when the information is available). That is, a list of publications that the publication under scrutiny cites. We also collect information about these referenced publications in order to run a citation analysis (i.e. whether or not

<footnote n="29"><sup>29</sup> Just as the WTID was an extension of the two collective volumes on top incomes directed by Atkinson and Piketty, these two projects are a continuation of collective books, the one under the direction of Thomas Piketty and two of his PhD students (Amory Gethin and Clara Martinez-Toledano), the other written by Cage and Piketty. See Gethin, Martinez-Toledano and Piketty (2021), Cage and Piketty (2023).</footnote>

<footnote n="30"><sup>30</sup> OpenAlex is a bibliometric and bibliographic database launched in 2022 whose objective is to index global scientific output in an open, transparent and reusable way, as an alternative to paywalled databases such as Elsevier's Scopus or Clarivate's Web of Science. All data is available under a CC0 licence. See the Appendix for a detailed presentation of how we use OpenAlex APIs for data collection. For details about OpenAlex, see Priem, Piwowar & Orr (2022).</footnote>
members of the inner circle cite each other in their publications and what these citations represent within these members' scientific output). All data was collected on September 29, 2025.

We find that over their entire academic careers, the proportion of research publications that each of these five authors co-authored with at least one of the other ranges from 39% (for Piketty) to 69% (for Zucman) (see Table 1). In total, members of what we identify as the “inner circle” co-wrote with at least one of such members in 119 research publications. Moreover, for each of these five authors, the list of the top-4 co-authors invariably contains the other 4 members of the inner circle, with Piketty ranking first for all but Zucman (although only 3 documents behind Saez, who is also the top-1 co-author of Piketty). Besides, we note that they write following diverse authorship formats between themselves, ranging from pairs (especially involving Piketty or Saez) to including several of them as is the case with the 2018 and 2022 World Inequality Reports (exception made of Alvaredo).

<table><caption>Table 1: Inner Circle - Co-Authorship Relations</caption><thead><tr><th>Author/Co-author</th><th></th><th>E. S.</th><th>F. A.</th><th>G. Z.</th><th>L. C.</th><th>T. P.</th><th>IC</th><th>N</th></tr></thead><tbody><tr><td rowspan="2">E. S.</td><td>with</td><td>-</td><td>44(22%)</td><td>56(28%)</td><td>37(18%)</td><td>71(35%)</td><td rowspan="2">91(45%)</td><td rowspan="2">202</td></tr><tr><td>with only</td><td></td><td>4(2%)</td><td>16(8%)</td><td>0(0%)</td><td>26(13%)</td></tr><tr><td rowspan="2">F. A.</td><td>with</td><td>44(55%)</td><td>-</td><td>37(46%)</td><td>40(50%)</td><td>51(64%)</td><td rowspan="2">55(69%)</td><td rowspan="2">80</td></tr><tr><td>with only</td><td>4(5%)</td><td></td><td>0(0%)</td><td>0(0%)</td><td>8(10%)</td></tr><tr><td rowspan="2">G. Z.</td><td>with</td><td>56(52%)</td><td>37(35%)</td><td>-</td><td>37(35%)</td><td>53(50%)</td><td rowspan="2">69(64%)</td><td rowspan="2">107</td></tr><tr><td>with only</td><td>16(15%)</td><td>0(0%)</td><td></td><td>0(0%)</td><td>11(10%)</td></tr><tr><td rowspan="2">L. C.</td><td>with</td><td>37(54%)</td><td>40(58%)</td><td>37(54%)</td><td>-</td><td>46(67%)</td><td rowspan="2">46(67%)</td><td rowspan="2">69</td></tr><tr><td>with only</td><td>0(0%)</td><td>0(0%)</td><td>0(0%)</td><td></td><td>6(9%)</td></tr><tr><td rowspan="2">T. P.</td><td>with</td><td>71(28%)</td><td>51(20%)</td><td>53(21%)</td><td>46(18%)</td><td>-</td><td rowspan="2">99(39%)</td><td rowspan="2">254</td></tr><tr><td>with only</td><td>26(10%)</td><td>8(3%)</td><td>11(4%)</td><td>6(2%)</td><td></td></tr></tbody></table>

Note: The table presents co-authorship relations among authors from the 'Inner Circle' (IC) based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. E.S.: Emmanuel Saez; F.A.: Facundo Alvaredo; G.Z.: Gabriel Zucman; L.C.: Lucas Chancel; T.P.: Thomas Piketty. The 'N' column indicates the total number of documents a given author wrote with at least one co-author. The 'IC' column indicates the number of documents the author listed in the row have written with at least one other member of the 'Inner Circle'. Cells in all other columns contain the
count and percentage of co-authored documents between two authors. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of co-authored documents (N column). Rows labeled 'with' indicate co-authorship relations between two authors. Rows labeled 'with only' indicate co-authorship relations between two authors that exclude co-authorship relations with any other author from the 'Inner circle'. For instance, T. Piketty co-authored 254 documents in our dataset, among which 71 were co-authored with E. Saez (hence 28% of all documents co-authored by Piketty). Also, Piketty and Saez wrote together 26 documents whose list of authors does not include Alvaredo, Zucman or Chancel (hence 10% of all documents co-authored by Piketty and 13% of all documents co-authored by Saez).

An analysis of the citations of these authors reveals similar patterns: they tend to cite each other often (the proportion of citations towards documents with at least one member of the inner circle ranges from 10% for Chancel to 19% for Zucman), with Piketty and Saez attracting the most citations (see Table 2). In addition, we observe that they cite each other in many (if not the large majority) of their works. For instance, Saez cites Piketty at least once in 46% of his works for which we find a referenced work in the database. Similarly, works (co-)authored by Saez are mentioned in 44% of Piketty's works. Overall, members of the inner circle cite members of the inner circle (including themselves) at least once in a minimum of 72% (for Piketty) to a maximum of 89% (for Zucman) of their publications.<fnref n="31" /> Finally, we also find that for all five authors A. Atkinson is within the top-5 of the most cited scholars, while S. Kuznets appears in the top-20 (see Table A.2).

<table><caption>Table 2: Inner Circle - Citation Relations</caption><thead><tr><th>Author/Cited</th><th></th><th>E. S.</th><th>F. A.</th><th>G. Z.</th><th>L. C.</th><th>T. P.</th><th>IC</th><th>N<sup>C</sup></th><th>N<sup>D</sup></th></tr></thead><tbody><tr><td rowspan="2">E. S.</td><td>cites</td><td>398(8%)</td><td>7(0%)</td><td>75(2%)</td><td>1(0%)</td><td>192(4%)</td><td>525(11%)</td><td rowspan="2">4856</td><td rowspan="2">132</td></tr><tr><td>docs with cites</td><td>106(80%)</td><td>5(4%)</td><td>27(20%)</td><td>1(1%)</td><td>61(46%)</td><td>110(83%)</td></tr><tr><td rowspan="2">F. A.</td><td>cites</td><td>61(5%)</td><td>26(2%)</td><td>15(1%)</td><td>0(0%)</td><td>82(7%)</td><td>139(12%)</td><td rowspan="2">1135</td><td rowspan="2">32</td></tr><tr><td>docs with cites</td><td>19(59%)</td><td>13(41%)</td><td>6(19%)</td><td>0(0%)</td><td>22(69%)</td><td>26(81%)</td></tr><tr><td></td><td>cites</td><td>122(8%)</td><td>9(1%)</td><td>171(11%)</td><td>3(0%)</td><td>131(8%)</td><td>301(19%)</td><td></td><td></td></tr></tbody></table>

<footnote n="31">³¹ We note one important limitation to our citation analysis: it is only based on publications for which the OpenAlex database provides connections with referenced works. In other words, it may exclude documents that do contain a reference list if this reference list does not translate into connections between documents in the database. Indeed, many documents co-authored by members of the inner circle are excluded when running such an analysis, simply because the database does not provide any referenced works for it. Attempting to correct the database would require an intensive manual work with reading access to all listed documents, which is beyond the scope of this paper. Our analysis should thus not be taken as face value but rather as indicative of a general pattern.</footnote>
<table><tr><td>G. Z.</td><td>docs with cites</td><td>38(72%)</td><td>6(11%)</td><td>42(79%)</td><td>3(6%)</td><td>35(66%)</td><td>47(89%)</td><td>1622</td><td>53</td></tr><tr><td rowspan="2">L. C.</td><td>cites</td><td>26(3%)</td><td>15(2%)</td><td>29(4%)</td><td>12(2%)</td><td>45(6%)</td><td>80(10%)</td><td rowspan="2">768</td><td rowspan="2">23</td></tr><tr><td>docs with cites</td><td>13(57%)</td><td>7(30%)</td><td>10(43%)</td><td>8(35%)</td><td>14(61%)</td><td>17(74%)</td></tr><tr><td rowspan="2">T. P.</td><td>cites</td><td>185(6%)</td><td>27(1%)</td><td>109(4%)</td><td>6(0%)</td><td>333(11%)</td><td>463(15%)</td><td rowspan="2">3096</td><td rowspan="2">116</td></tr><tr><td>docs with cites</td><td>51(44%)</td><td>17(15%)</td><td>33(28%)</td><td>5(4%)</td><td>83(72%)</td><td>83(72%)</td></tr></table>

Note: The table presents citation relations among authors from the 'Inner Circle' (IC) based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. E.S.: Emmanuel Saez; F.A.: Facundo Alvaredo; G.Z.: Gabriel Zucman; L.C.: Lucas Chancel; T.P: Thomas Piketty. The N<sup>c</sup> column indicates the total number of documents a given author cites. The N<sup>d</sup> column indicates the total number of documents for which the database contains at least one referenced work. The 'IC' column contains the count and percentage of citations directed to documents written by at least one member of the 'Inner Circle' that is not the author listed in the row. Cells in all other columns contain the count and percentage of documents written by the column author and cited by the row author. Rows labeled 'cites' indicate citation relations between two authors. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of cited documents (N<sup>c</sup> column). Rows labeled 'docs with cite' indicate the number of documents written by the row author that cite the author. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of documents that contain at least one reference in the database (N<sup>d</sup> column). For instance, T. Piketty wrote 116 documents which contain at least one referenced work. These documents cite 3096 documents, among which 185 were written by E. Saez (hence 6% of all documents cited by Piketty). Also, Piketty cites Saez in 51 documents, that is in 44% of Piketty's documents in which there is at least one reference.

One could wonder about the place of Julia Cage, a Professor of Economics at Sciences Po Paris (like Lucas Chancel), Piketty's long-time collaborator and present wife, with respect to the "inner circle". Her influential works on political inequality and democracy have fueled Piketty's books and the latter acknowledged in an interview that both played an important role in the writings of each other's recent books.<fnref n="32" /> Their collaborative writing process took a more explicit form with the publication in 2023 of their book on social inequality, political conflicts and the history of voting in France, published by Le Seuil, the French editor of the works of the WIL<fnref n="33" />, this time in a specific and recently created collection called "ECO-HISTOIRES" launched and managed by Cage and Piketty themselves (see Cage et Piketty, 2023). Interestingly, the latest

<footnote n="32">³² Voir https://www.youtube.com/watch?v=KiKqml5550U, 23-24 minutes.</footnote>

<footnote n="33">³³ See Zucman (2013), Saez and Zucman (2019). See also the different WIR.</footnote>
publication of the “ECO-HISTOIRES” collection is a book by Lucas Chancel (Chancel, 2025). Cage and Piketty’s book was recently added to the “Projects” section of the *WIL* and Cage is now a WID “fellow”. So, in a way, she is part of Piketty’s inner circle but also of the school of which she fully shares and incarnates the values and the view of economics (see below, sections 2.4 and 3).

Then there is what we can call the “wider circle”, made up of the collaborators and contributors of the ever-growing international network of the WIL. Within this wider circle, we would include two groups that are connected to the inner circle from an institutional perspective: other members of the WIL, the heart of the inequality school, and other WID Fellows. Notably, these two groups include many past and present students from members of the inner circle (and in particular of Piketty), such as Gethin, Goupille-Lebret, Martinez-Toledano, Blanchet, etc. Looking at the list of WIL-affiliated scholars and WID Fellows as of September 2025 and searching for their publications after 2015 (that is the creation date of the WIL and the WID), we find that many works are indeed co-authored with members of the inner circle or across these two groups (see Table A.3). For instance, among the 103 documents co-authored by WIL scholars that are not part of the inner circle, approximately two thirds of documents involve either one member of the inner circle, one member of these same WIL scholars, or one member of the WID Fellows that are not part of the WIL. Interestingly, Piketty alone co-authored about a fifth of such research publications. Regarding WID Fellows, who constitute a much bigger and more diverse set of authors and may consequently be more distantly connected to the inequality school, as emphasized by the fact that the majority of publications takes place outside of both the inner and outer circles, we still observe that they work with one another and that they co-author works with the inner-circle and with the remainder of the WIL (totalling about 10% of WID Fellows publications).<fnref n="34" /> The analysis on citations yields similar results. In particular, although the share of citations from the various groups towards these groups is small given the overall number of citations, the various authors and groups are present in many documents written by other authors/groups (see Table A.4). For instance, members of the WIL (resp. WID Fellows) refer to members of the Inner Circle in 31% (resp. 15%) of their publications. Again, Piketty and Saez attracts the most citations from these two groups. All groups also frequently refer to WID Fellows (in two thirds of documents for members of the

<footnote n="34">³⁴ We also notice that the share of publications by members of the Inner Circle with other members of the Inner Circle among their co-authored publications is higher than in Table 1 for all combinations of authors. In other words, they co-authored works more frequently after the creation of the WIL/WID than before.</footnote>
Inner Circle, in almost half of documents for members of the WIL, and in a third of documents for WID Fellows).<fnref n="35" />

Beyond the distinction we have made, with all its limitations, the research made by the members of the IRNOI of the WIL is a collective enterprise, a truly collaborative and cooperative process, making it a research community or network of strongly related, united and, for some of them, very influential economists (in particular Piketty, Saez, and now Zucman), who play a big role in the very hierarchical science that economics is.<fnref n="36" /> They put the issue of distribution back at the centre of economic discourse and public debate through successful (wide-audience) books and publications in top-ranked economic journals, especially the *American Economic Review* and the *Quarterly Journal of Economics*, which are quite influential in the field.<fnref n="37" />

## 2) The main characteristics of the IRNOI of the WIL

So far we have identified members of what we called the International Research Network On Inequality (IRNOI) working at and collaborating with the WIL, respectively the members of the WIL (including the inner circle) and the WID fellows. In our view, such members are not only connected to one another within a research network: they also qualify as “practictioners” for a new school of economic thought. In this section, we will focus on what makes their identity and distinctiveness, i.e on their “system of thought”. In particular, we would like to underline the deep coherence and homogeneity of the works of this community of scholars studying the global history of economic inequality. To be more precise, we claim that there is among them, and especially among WIL members in the strict sense,<fnref n="38" /> a very clear unity in terms of topic, methodology, explanation of (rising) inequality, policy proposals and ethical values.

### 2.1 Topics - Object of study

As to the first point, and although there obviously exists some degree of heterogeneity across authors, it appears that members of the IRNOI of the WIL share a specific object of study,

<footnote n="35">³⁵ Notably, members of the WIL that are not members of the Inner Circle do not represent an important share of overall citations or documents from the other groups (e.g. only 7% of documents for Inner Circle and 3% for WID Fellows). But one should also bear in mind that such scholars are mostly young researchers, whose work may not have been cited frequently yet, even from a broader perspective.</footnote>

<footnote n="36">³⁶ On the strong and excessive hierarchy in economics and its pernicious consequences, see Wright (2024).</footnote>

<footnote n="37">³⁷ On the importance and dominance of economics’ Top 5 journals, see Heckman and Moktan (2020).</footnote>

<footnote n="38">³⁸ Of course, it is not possible to know with certainty and thus to claim that all WID fellows share everything we identify here in section 2 and 3 as the characteristics of the school. That’s why in these sections we refer mainly to “the members of the WIL”.</footnote>
which is the historical dynamics of socio-economic inequality and its (political and ideological)
causes. This is rather explicit upon reading these authors' most influential works, but we can
also rely on the bibliometric data that we gathered for the above analysis of co-authorship and
citation links. Indeed, for most documents the OpenAlex database associates a list of at most 3
"topics", which are meant to accurately and succinctly describe what the document is about.
Topic assignment is automated using machine learning techniques that rely on the document's
title, abstract, citations and journal name.<fnref n="39" /> Figures 1 as well as A.1 to A.13 depicts for the
(groups of) authors we are interested in the number of times a topic (among the 20 most frequent
topics) is associated with their works. The number above each bar is the average score (S) the
prediction model assigns to the topic over all documents that are associated with this topic. It
is thus a measure of topic-assignment uncertainty.

Regarding the “inner circle”, we find that 3 three topics are most represented when members of
this group write together (119 documents, see Figure 1): “Fiscal Policy and Economic Growth”,
“Income, Poverty and Inequality”, and “Economic Theory and Policy”. For each of these topics,
the average prediction score is high, meaning these topics are highly likely to be a good fit to
characterize the documents.

Figure 1 :

<footnote n="39"><sup>39</sup> More information can be found in OpenAlex documentation at https://docs.openalex.org/api-entities/topics.</footnote>
<figure><img src="image_2.png" /></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least two members of the Inner Circle (IC) based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics correspond to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.

Moreover, the same three topics also stand out when considering all the documents written by members of the inner circle (thus pooling research publications, even solo-authored ones) (see Figure A.1). Detailing the analysis per author, we observe some differences in the relative importance of these three topics and the presence of other topics (such as taxation issues for Zucman, or the topic “Social Policy and Reform Studies” for all but Saez), but in any case these three topics are always present in the 20 most frequent topics and always with an average prediction score above 80% (see Figures A.2 to A.6).

When considering the wider circle, looking at research publications after the creation of the WIL/WID, the prevalence of the “Income, Poverty and Inequality” topic is even clearer. In fact, it is almost always the topic associated with the highest number of documents (and often by a
large margin), no matter whether we consider only co-authored documents or all documents published by at least one author of the groups under scrutiny, and no matter how we define the groups (e.g. considering only members of the WIL that are not part of the inner circle), see Figures A.7 to A.13.<fnref n="40" /> The topic “Fiscal Policy and Economic Growth” also stands out quite consistently throughout. As a consequence, we take such findings as evidence that the study of inequality is indeed what binds all these authors together.

But inequality of what? Members of the IRNOI of the WIL focus on *individual* measures of inequalities of (monetary) *resources*, rather than on inequalities of expenditures, welfare, opportunities, access to health and education, or capabilities. In other words, they are mainly interested in the *individual* distribution of *income* and *wealth*, therefore using a distinct but unidimensional view of inequality, while studying its historical evolution and its various aspects: the role of inheritance, redistribution (the impact of taxes and transfers on the levels of inequality), tax avoidance and evasion, global inequality (within and between countries), voting and democracy, environmental inequality (of carbon emissions) and gender (economic) inequality (see WIR 2022), as well as more recently individual perceptions of inequality. In other words, they mainly study individual inequalities rather than class inequalities, as in Marxian economics, or group inequalities, the focus of “stratification economics”<fnref n="41" />, though they started investigating racial inequality.<fnref n="42" />

## 2.2 Methodology

On methodological ground, and in line with the empirical tradition in economics, their work is based first and foremost on collecting and providing individual long-time series of data on incomes and wealth, allowing to reconstruct a comparative history of inequality (and of “inequality regimes”, see Piketty, 2019), through the extensive use of various sources, and specifically of fiscal data,<fnref n="43" /> which were until recent years difficult to access and process and thus neglected by researchers. In addition to fiscal data, they also use archives, surveys, national accounts and Forbes lists in order to estimate then the respective shares of the (top) 0,1%, 1% of the population, 10%, middle 40%, and bottom 50% in total income or wealth of a country or region of the world in different periods of time. In other words, their measures of inequality

<footnote n="40">⁴⁰ Interestingly, it appears that when we consider documents written by members of the WIL without the inner circle or written by WID Fellows without members of the WIL, the prevalence of the “Income, Poverty and Inequality” topic is even more conspicuous (see Figures A.9 and A.13).</footnote>

<footnote n="41">⁴¹ On the origins and foundations of stratification economics, see Davis (2024).</footnote>

<footnote n="42">⁴² See Govind, Santini, and Derenoncourt (2025).</footnote>

<footnote n="43">⁴³ Piketty underlined that following the success of his book *Capital in the Twenty-First Century*, more and more public administrations have opened their data to researchers.</footnote>
rely on statistical categories like centiles and deciles rather than on synthetic indicators like the Gini, Theil or Atkinson indexes. But the measurements of income and thus of individual income inequality raise important methodological issues which are best exemplified by the recent controversy between Auten and Splitter on one side, and Piketty, Saez and Zucman on the other (see Auten and Splinter, 2024a, 2024b; Piketty, Saez and Zucman, 2024), on the rise of income inequality in the USA, the former finding a much less important increase in inequality than the latter (see Clarke and Kopczuk, 2025).

Beyond the controversies over the estimation of the shares of the upper 1 or 10% of the population, and thus of economic inequality, it is noteworthy that Piketty acknowledges that the choice of measurement tools, i.e of socio-economic indicators, is an eminently political choice. Choosing to focus on the share of the top 1% or 0,1% in total income and wealth rather than on the Gini coefficient, as members of the IRNOI of the WIL do, has an obvious political appeal and is easier to understand for the public (see Piketty, Saez and Zucman 2022, p. 2). For him, this choice of indicators should be democratically debated, and he acknowledges the limitations of his statistics on inequality, of their unidimensional representation of the complex and multidimensional phenomenon of inequality (Piketty, 2021, pp. 29, 36-8).<fnref n="44" />

Methodologically speaking, and still in line with their empirical view of economics, they have recently introduced a significant innovation that Boushey sees as a revolution comparable to the emergence of the first national accounts in mid-20th century (Boushey 2020): the creation of *Distributional National Accounts* (DINA) in order to realize Simon Kuznets’s “unachieved program”,<fnref n="45" /> a project Atkinson was involved in just before his death (see Piketty in Aaberge et al. 2017). While we have already mentioned the influence on and involvement of Atkinson in the beginning of the IRNOI leading to the creation of the WIL, the other main precursor and inspirator of the school is undoubtedly Kuznets. Having common references is important for building the unity of a school, and here they follow in the footsteps of two very prestigious economists: Kuznets won the Nobel Prize in 1971 and Atkinson, though he never got it, was often seen as a real contender, as we noticed. Kuznets was a pioneer in the empirical and historical study of economic inequality with his 1953 book called *Shares of Upper Income*

<footnote n="44">⁴⁴ On the various issues raised by the choice of inequality indicators, see Ramos Pinto and Paidipaty (2020), O’Connor (2020), Reddy (2020).</footnote>

<footnote n="45">⁴⁵ “We talk about growth, we talk about inequality but never about the two together. Kuznets and others, in parallel, looked at tax data to study the description of income as reporting tax returns, but they never bridged the gap between GDP and income and taxes. So, what we tried to do is to complete the Kuznets agenda of GDP looking at the description of income between these two things in a common and consistent conceptual framework.” (Boushey and Zucman, 2018 quoted in Boushey, 2020)</footnote>
*Groups in Income and Savings*<sup>46</sup> on income inequality in the US from 1913<sup>47</sup> to 1950, a book which is repeatedly quoted by people working on inequality measurement, and especially by the members of the WIL who see their own work as an extension in time and space of his program (see Piketty 2014, introduction, 16-17, and the description of the *WID*<sup>48</sup>). Kuznets became a member of the *National Bureau of Economic Research (NBER)* in 1927 and led a team there in the early 1930s to develop what will become US national accounts, while launching in 1936 the *Conference on Research in Income and Wealth* (Rutherford, 2005, p. 118; Fogel & al, 2013, pp. 110-12). Then he was involved in the beginnings and development of *The Review of Income and Wealth*, launched in 1951<sup>49</sup>, whose 2<sup>nd</sup> series he edited in 1952 (see also the 5<sup>th</sup> series in 1955). This journal was instrumental in publishing pioneering works on national income but also empirical studies on income and wealth distribution. Much influential too was of course Kuznets's 1955 paper in which he presented what would be known then as the “Kuznets curve”, optimistically predicting a long-term decrease of inequality with economic development, after a first phase of increase (Kuznets, 1955; see Piketty’s interesting discussion of the context of elaboration, motivation, and influence of Kuznets’s curve in Piketty, 2014, pp. 13-15). So, Kuznets initiated and developed a kind of two-headed “research program” on both national accounts and the distribution of income and wealth (see Piketty, 2014, p. 12, note 11), that the WIL is trying to reconcile or merge now with the elaboration of “Distributional National Accounts” (DINA).<sup>50</sup>

Indeed, as rightly noted by Alvaredo et al. (2022, p. 2), in the early years of the system of
national accounts “national accountants were also experts in distributional issues, as the inter-
linkages between the estimation of national income and its distribution were clearly recognized”
and it is only in the subsequent decades that their link was lost and “the two fields went separate
ways”.<fnref n="51" /> Concretely, DINA aims at mixing data on national income and its distribution,
disaggregating national income accounts and providing a coherent analysis of growth and

<footnote n="46">⁴⁶ Other pioneering works include Frankel & Herzfeld (1943) (quoted in Alvaredo et al., 2020), Procopovitch (1926), and *Income Size Distributions in the United States* (CRIW 1943), 5ᵗʰ publication of the Conference for Research in Income and Wealth for NBER (or Studies in Income and Wealth, vol 5) (for more details on this see Fogel & al, 2013, pp. 110-12). The survey was conducted by a committee including Milton Friedman, and the volume’s introductory chapter 1 was prepared by Kuznets.</footnote>

<footnote n="47">⁴⁷ When the income tax was introduced in the USA after a harsh political battle, with very low tax rates and progressivity. But very soon the marginal top tax rates increased to reach 67% in 1917 and around 90% in 1950 (see Saez and Zucman, 2019).</footnote>

<footnote n="48">⁴⁸ https://wid.world/wid-world/</footnote>

<footnote n="49">⁴⁹ Note that Kuznets had a paper in this first issue/series of the *Review of Income and Wealth* (see Kuznets, 1951), On the history of the journal, launched after the first conference of the International Association for Income and Wealth, see the Preface to this first series by Erick Lundberg.</footnote>

<footnote n="50">⁵⁰ For more details on Kuznets’s specific “vision of inequality”, see Milanovic (2023, chapter 6, pp. 189-216).</footnote>

<footnote n="51">⁵¹ As a prime example, see Kuznets, Epstein, and Jenks (1941).</footnote>
inequality. It allows then to estimate the fairness or “inclusiveness” of growth<fnref n="52" /> (see Piketty, Saez and Zucman, 2018; Alvaredo et al., 2020; Saez and Zucman, 2019, 2020; Garbinti, Goupille-Lebret and Piketty, 2018), as well as the effects of redistribution by highlighting the difference between pre-tax and post-tax (and transfers) inequality (Piketty, 2019, p. 617; Blanchet, Chancel and Gethin, 2022; Fisher-Post and Gethin, 2023). Applied to the USA, it led to the creation of the website “Real Time Inequality”,<fnref n="53" /> hosted by the WIL, allowing a real-time and constantly updated visualization of who benefits most from the growth of income and wealth in this country.<fnref n="54" /> More fundamentally, the aim of this project is to bridge the gap between macroeconomics and inequality studies.<fnref n="55" />

## 2.3 Policy Proposals

But members of the WIL do not simply measure inequality, they also discuss their causes, and above all *how to reduce them*. As to the explanations of rising inequality since the 1980 all over the globe, that they were able to document and rationalize with their works, there is also a very strong unity among them. Contrary to what one could expect from economists, they focus on the political and ideological causes of growing inequality, rather than on economic or technological causes (like globalisation, innovation, restricted competition, increased flexibility of work, or decreasing unionization...), particularly insisting on the key role of taxation policy (see WIR 2022, preface from Banerjee and Duflo, and pp. 11, 20; Piketty, 2020; Saez and Zucman, 2019). This is reflected in their common and recurrent policy proposals for a more progressive taxation of income, but also for a progressive taxation of wealth and inheritance. Indeed, they offer many proposals for reducing the concentration of property and income inequality, pleading for redistribution through progressive taxation (with significantly higher top marginal tax rates on incomes), especially via an annual wealth tax (see Piketty, 2014 and his global wealth tax<fnref n="56" />; Piketty, 2019; Zucman, 2013; Saez and Zucman, 2019; Saez, 2021;

<footnote n="52">⁵² On the idea of equitable growth and its defense, see also Boushey (2019). She is a former President and CEO of the Washington Center for Equitable Growth and has been a member of the Council of Economic Advisers under Biden administration. In an interview with her in 2013, Robert Solow said: “I really do think that this question of equitable growth is certainly one of the, if not the central economic issue of our time”. See also Boushey (2013), Naidu, Rodrik and Zucman (2020), especially p. 366 on the broad definition of inclusive growth, beyond the distribution of income of wealth.</footnote>

<footnote n="53">⁵³ See Blanchet, Saez and Zucman (2022).</footnote>

<footnote n="54">⁵⁴ https://realtimeinequality.org/</footnote>

<footnote n="55">⁵⁵ “We should make clear that the long-run objective of WID.world – i.e. the production of annual Distributional National Accounts (DINA) describing the entire distribution of income and wealth, from bottom to top, using concepts consistent with macroeconomic national accounts – will be implemented gradually.” (https://wid.world/methodology/)</footnote>

<footnote n="56">⁵⁶ In his 2001 book on the history of economic inequality in France, Piketty already noted the importance of progressive taxation for reducing the concentration of wealth and economic inequality in general.</footnote>
Zucman, 2021; Saez and Zucman, 2022; WIR 2022, chap 7 with different schemes and how much they could raise; Chancel, Bothe and Voituriez, 2023; Piketty, Saez and Zucman, 2023; WIR 2026, chap 7; see also Bharti & al 2024, for India). They also formulate concrete policy proposals for fighting tax competition and evasion (see in Saez and Zucman, 2019 their promotion of a minimum tax rate of 25%, without exemptions, for corporations; see also WIR 2022, chap 8, pp. 150-52 and *Global Tax Evasion Report 2024*, chap 5, pp. 71-90), and argue for the creation of a global financial register (see Zucman, 2013, 2014; WIR 2018, 5.3; WIR 2022, chap 9, pp. 160-63), which could serve as a matrix for the global wealth tax they are calling for. Last but not least, they defend the social state and its role in the reduction of inequality by advocating for more public investments in public goods and services, especially in health and education (Piketty, 2013, 2019; Saez and Zucman, 2019; Saez, 2021, WIR 2022, chap 10).

## 2.4 Values

From an ethical or axiological point of view, the proposals made by the members of the WIL rely on similar moral values and goals or normative foundations, though the latter are not always much discussed in their works (see though Piketty, 2020, chapter 17; Piketty and Sandel, 2025). For sure, they are committed to equality and claim that they endorse Rawls's difference principle according to which inequalities of income and wealth are just when they (maximally) benefit to the least well-off in terms of standard of living and opportunities (see Piketty 2020, chapter 17; Saez and Zucman, 2019). They want to foster a more inclusive, equitable growth (see Saez's and Zucman's involvement in the *Economics for Inclusive Prosperity Project*),<fnref n="57" /> and in general to promote justice, equality, fairness (see Saez, 2017), and democracy (Piketty, 2020; Saez and Zucman, 2019). That being said, their normative policy proposals are also based on their study of history from which, they argue, we should draw some lessons, for example about the crucial role that the social state and progressive taxation played in the reduction of inequality during most of the 20th Century (see especially Piketty, 2020, 2022; see also Saez and Zucman, 2022, note 8). In any case, in terms of ideology, broadly defined, they have strong, revendicated affinities with socialism<fnref n="58" /> or more precisely with social democracy, as had Atkinson.<fnref n="59" /> Nowhere is this more visible than with Piketty, who wants to extend what he

<footnote n="57">⁵⁷ https://econfip.org/about/</footnote>

<footnote n="58">⁵⁸ Piketty is a revendicated socialist and often advised candidates of the French socialist party, while Saez and Zucman advised the Democrats in the USA, as mentioned before.</footnote>

<footnote n="59">⁵⁹ On the role and influence of Atkinson on social democracy in the UK, see Tomlinson (2020). The latter interestingly notes that what was missing in Atkinson, and in economic studies of inequality in general, is the</footnote>
considers as the main benefits of social democracy, the social state and progressive taxation, seen as the main instruments for reducing inequality. In his latest books, he argued for a new socio-economic model and ideology, “participative socialism”, a democratic, decentralised, self-managed, and ecological form of socialism (see Piketty, 2020, 2022). It is presented as an alternative to what he calls “neoproprietarianism” with its tendency to sacralise private property and its defence of the alleged meritocracy of the market, naturalizing existing inequality. Participative socialism would guarantee an equal access to “fundamental” or “basic goods” (health, education, the right to vote and everything necessary to actively participate in the economic, political and social life) and would foster a social and temporary property through a steeply progressive taxation of incomes, wealth and its transmission, a capital endowment for all,<fnref n="60" /> and with measures in favour of economic democracy, redistributing power inside firms. Piketty is convinced that history is moved by the struggle of ideologies and the quest for justice and equality, to which he wants to actively participate in. For him, there is a long run trend towards equality and human progress in history, at least since the end of the 18th century, and it could and should be continued, though nothing is guaranteed (Piketty, 2020, 2022). Following him, the members of the WIL are a group of egalitarian economists who sometimes do not hesitate to prioritize equality over efficiency, as we can see with Piketty’s proposals for a highly progressive taxation of income, wealth, and inheritance (with top marginal tax rates of 90% for all three) as well as in Saez and Zucman’s call to go “beyond Laffer” to preserve American democracy from a plutocratic drift (see Piketty, 2020; Saez and Zucman, 2019). Economic inequality matters for them because it creates problems of access to basic goods for all, it undermines political equality and it can erode social recognition and human dignity (see Piketty and Sandel, 2025). As attests their latest project, the “Global Justice Project”, members of the WIL share a view of what a good and just global economic system should be, a system which can guarantee true socio-economic equality and planetary habitability, and they will defend its implementation through policy proposals for a radical transformation of the global production system and of international monetary and financial institutions.<fnref n="61" /> For the members of the WIL

<footnote>analysis of the (re)distributional impact of social services, transfers, and benefits in kind (Tomlinson, 2020, pp.530-31).</footnote>

<footnote n="60">⁶⁰ The idea to distribute a capital endowment to every citizen was also proposed by Atkinson in his book *Inequality. What Can be Done?*, published in 2015, to which Piketty paid tribute on his blog post after Atkinson’s death for his bold and radical proposals on redistribution.</footnote>

<footnote n="61">⁶¹ https://inequalitylab.world/en/global-justice-project/</footnote>
"Inequality is a policy choice. Combating it is both necessary and possible"<fnref n="62" /> Their numerous proposals for reducing inequality aim to foster social justice and climate justice.

### 3) The members of the WIL and their view of economics

#### 3.1 Economics as a social, political, historical and moral science

We would like to show now that what also distinguishes the members of the inequality school from many other schools of thought in economics, and specifically of mainstream or orthodox economic thinking, is their view of economic science. Indeed, it presents economics as a deeply empirical and yet policy-oriented science, but above all as a historical, political, social, and moral science. An *historical* science in that the inequality school offers long-term data series on the individual distribution of income and wealth,<fnref n="63" /> but also more generally because Piketty, who has collaborated with historians, never hid his interest for history and its admiration for and debt toward the French *Annales school* of history, as we underlined.<fnref n="64" /> In *Capital and Ideology* (Piketty, 2020) he tries to provide an ambitious comparative, “global” and reasoned history of inequality in its economic, social, political, and intellectual dimensions.<fnref n="65" />

Economics is seen as a *political* science then, because it studies how tax systems and political ideas and choices about taxation affect economic and social inequality (Piketty, 2019, 2021). It analyses also the influence of economic and social inequality on people's votes (see Gethin, Martinez Toledano and Piketty, 2022; Cage and Piketty, 2023), or in Piketty's terms the underlying “ideologies” and institutions of “inequality regimes”. More generally, economics is seen as being at the heart of *social* sciences.<fnref n="66" /> Piketty, who considers himself as a social scientist rather than merely an economist, is very critical of the autonomy of economics and of its imperialistic pretentions. That's why in his books he always pleads for more interdisciplinarity in economics. It can be seen as a welcome call knowing that economics has long been, and still

<footnote n="62">⁶² Statement from the World Inequality Lab on the G20 Extraordinary Committee of Independent Experts' Report on Global Inequality - WID - World Inequality Database</footnote>

<footnote n="63">⁶³ There are obvious links between the works of the inequality school and new economic history or cliometrics, though the members of the school do not explicitly acknowledge it.</footnote>

<footnote n="64">⁶⁴ Piketty also acknowledges his debt toward “serial history” (see Piketty 2015). On the rise and fall of the latter in historical research, see Müller (2021).</footnote>

<footnote n="65">⁶⁵ Remember that, inside PSE, Piketty and Alvaredo are members of the *François Simiand Center for Economic and Social History*.</footnote>

<footnote n="66">⁶⁶ On Piketty’s vision of economics as a social, historical and political science, see Piketty (2014, conclusion, pp. 573-75), Piketty (2020, conclusion, pp. 1039-41), Piketty (2021) This view of economics at the heart of social sciences shares some affinities with the one defended by the French regulation school, as he acknowledged in an interview in the *Revue de la régulation*, the journal of this school (Piketty & al, 2020). See also the review of *Capital in the Twenty-First Century* by Robert Boyer, one of the founders of regulation theory (Boyer, 2013).</footnote>
is, an insular science, though it made some progress toward more interdisciplinarity during the last decades, but mainly outside the top 5 journals (see Truc et al, 2023). Finally and maybe more controversially, economics is considered as a moral<fnref n="67" /> and normative science whose end is to feed the permanent democratic debate on social justice, to foster equality, justice, and human progress, and to help reaching a more inclusive and fair growth by promoting concrete policy proposals for reducing inequality, in line with Piketty’s belief in the power of ideas to change the world and the course of history (see Piketty, 2019). As we saw too, members of the WIL, the heart of the inequality school, share a view of and defend what a “good” socio-economic system should be, fostering socio-economic equality and environmental sustainability. For all these reasons, Piketty prefers to use the old-fashioned “political economy” rather than “economic science”.<fnref n="68" /> Works of the members of the IRNOI of the WIL are characterized by a mix of history, quantitative data and concrete policy proposals.

## 3.2 The social role of economists

Besides and relatedly, the members of the inequality school, and especially their leaders, defend a certain, uncommon vision of the role of economists in democracy. For them, the aim of economics, or political economy as a social science is not merely to guide and advise politicians and/or the elite (the old, classical view of the economist as “advisor to the prince”), it is also and maybe more importantly to educate, *enlighten* and *empower* citizens to make their own well-informed and thus more “rational” political choices (see Saez and Zucman, 2019⁶⁹) about taxation and redistribution. They try to contribute to a more democratic, inclusive debate on these issues, and to create a better dialogue between civil society, economists and legislators.<fnref n="70" />

<footnote n="67">⁶⁷ See Piketty, Saez and Zucman (2022, 2) on the analysis of economic inequality and the quest for justice and equality.</footnote>

<footnote n="68">⁶⁸ “I see economics as a subdiscipline of the social sciences, alongside history, sociology, anthropology, and political science. I dislike the expression “economic science,” which strikes me as terribly arrogant because it suggests that economics has attained a higher scientific status than the other social sciences. I much prefer the expression “political economy,” which may seem rather old-fashioned but to my mind conveys the only thing that sets economics apart from the other social sciences: its political, normative, and moral purpose.” (Piketty, 2014, pp. 573-74)</footnote>

<footnote>It is interesting to note that at the end of his career, Lionel Robbins, usually known for his defense of a value-free science of economics focused on analyzing behavior conditioned on scarcity, provided a similar distinction between such an economic science and a normative, moral political economy related to politics and history, pleading for the latter in the application of economic science to problems of policy. See Robbins (1981),</footnote>

<footnote n="69">⁶⁹ While a 19-year-old student at the ENS, Zucman had created a broad-audience review, *Regards croisés sur l'économie*, whose aim was already to popularize economic research and to illuminate public debate on policy issues and whose first issue was devoted to ... taxation! (Saez, 2024, p. 228).</footnote>

<footnote n="70">⁷⁰ For a similar idea of the democratic role of economists, see Broome (2008, especially p. 13-14):
> « Democracy has at least two departments. One department is decision-making, and here democracy requires that the people’s preferences should prevail. [...] Another department of the democratic political process is the forming of people’s preferences. A democratic society cannot just let these preferences be whatever they happen to be. Our</footnote>
For this purpose, in addition to providing an open access to their data, they have developed specific, visual tools such as fiscal simulators. The first one was made for France in 2011, a few months before the Presidential election, as a complement to a book by Landais, Piketty and Saez (see Landais, Piketty and Saez, 2011). Then in connection with the book *The Triumph of Injustice* (Saez and Zucman, 2019), a second one was crafted especially for USA in 2019, again during the Presidential Campaign, for which Saez and Zucman advised different candidates of the Democratic Party on taxation and especially on the implementation of a wealth tax (see below).<fnref n="71" /> Then a new fiscal simulator about the implementation of a wealth tax for other countries and regions of the world as well has been developed on the WIL website. The new version of the Global Wealth Tax Simulator was presented in April 2025 during the international conference called “Taxing Billionaires” organized by Zucman’s *EUTO*.<fnref n="72" />

### 3.3 Economics and democracy

Along these lines, while it is now well-documented that people have a poor knowledge of actual levels of inequality even inside their own countries, and generally tend to underestimate them (see Houser and Norton, 2017), members of the WIL insist on the *democratic* importance of a diffusion of and open access to economic data on inequalities of income and wealth for everyone (see Piketty, 2014, introduction, p. 3). On the homepage of the WIL website, we can read that they aim at “Empowering civil society, reinforcing democracy. Powered with data” and that the WIL “gathers *social scientists* committed to *helping everyone understand the drivers of inequality* worldwide through evidence-based research.” (we underline)<fnref n="73" /> The open access to data and fiscal simulators together provide some necessary epistemic conditions for reasonable and enlightened debates about the efficiency and justice or injustice of inequalities, taxation, and redistributive systems, and more generally for a sound deliberative and participative democracy that Piketty explicitly calls for in *Capital and Ideology* (see Piketty, 2019, chapter 17). He repeatedly claims that economic knowledge should not be the monopoly

<footnote>preferences about complex matters depend on our beliefs, and democracy requires a process of discussion, debate and education, aimed at informing and improving people's beliefs, and moving them nearer the truth. This is why we have election campaigns as well as elections. The role of economists in a democracy is in the second department. [...] Their role is within the process of discussion, debate and education, and not much in the decision-making department of democracy. This means their job is not to garner people's preferences and act on them in a democratic fashion. It is to contribute to the public debate, in order to influence people's preferences for the better. Economists should aim to influence preferences, not take preferences for granted. In forming their preferences about complex matters, people naturally need advice, and an important job for economics is to give it to them. Economists should not see themselves as advisers to the high and mighty only, but also as advisers to the rest of us. »</footnote>

<footnote n="71">⁷¹ See https://www.taxjusticenow.org/#/</footnote>

<footnote n="72">⁷² See https://wid.world/world-wealth-tax-simulator/</footnote>

<footnote n="73">⁷³ https://inequalitylab.world/en/</footnote>
of economists and asks for a citizens’ reappropriation of that knowledge (Piketty, 2020, pp. 1039-41; 2022a, p. viii). For the members of the WIL, even the choice of socio-economic indicators must be submitted to public debate and democratic face-off, as attests Piketty’s tract on the measurement of racial discriminations (Piketty, 2022b). And they ask for an engagement of economists into the policy world (see Naidu, Rodrik and Zucman, 2020), as attest their numerous and recurrent policy proposals. To sum things up, they emphasize the political or democratic role of economists and the need for more interdisciplinary thinking in economics (see in particular Piketty, 2020, pp. 1039-41).<fnref n="74" />

On this point, members of the WIL and their closest collaborators seem to follow and answer to Irving Fisher’s more than centenary call for the democratization of economic knowledge in his December 1918 presidential address to the American Economic Association, in which he also stressed that there was at that time “an undemocratic distribution of wealth”:<fnref n="75" />

> “In order that our influence may be fully exerted, I believe two new agencies are needed—one designed to diffuse such economic knowledge as we possess among the people who do not possess it, and the other designed to increase that knowledge. [...] An urgent need, in my opinion, is some organized machinery for diffusing economic principles among the masses of our population. The common people, whose ideas will, more and more, rule the world, are in crying need of competent instruction in economics, simplified and reduced to its lowest terms. In a democracy the people express their opinion on economic problems, but without much opportunity, in the first instance, to make that opinion intelligent.” (Fisher, 1919, pp. 19-20)

People, he adds, often suffer from “a lack of economic enlightenment”, from “delusion”, and yet can be “emancipated” from certain “doctrines” (*ibid*, p. 20). The following year, the *NBER* was born to study the distribution of national income, and quickly recruited Simon Kuznets, a former student of Wesley Clair Mitchell (the first director of research of *NBER*), whose works have inspired the research agenda of the WIL, as we saw earlier.<fnref n="76" /> In Piketty’s view, the WIL and its reports, providing people with ever more reliable and open data on inequality, should be

<footnote n="74">⁷⁴ As was mentioned before, Cage and Piketty now run a collection called ‘ECO-HISTOIRES’ for the French editor *Le Seuil*, publishing books (including their own first common book) which reflect the view of economics promoted by the inequality school. Indeed, ‘ECO-HISTOIRES’ is described as “another way of writing economics, putting it back at the heart of the social sciences, civic life and public debate. ÉCO-HISTOIRES is based on a strong conviction: our contemporary democratic disarray stems from an excessive autonomy of economic knowledge vis-à-vis the other social sciences and the civic and political spheres. In reality, only by combining economic, historical, sociological, cultural and political approaches can we make any progress in our understanding of socio-economic phenomena.” See https://www.seuil.com/collection/eco-histoires-14613</footnote>

<footnote n="75">⁷⁵ In their 2019 book, Saez and Zucman mention Fisher’s speech to the American Economic Association and his view that the distribution of wealth was undemocratic at that time in the US. But surprisingly, they do not refer to the passage quoted here on the necessary democratization of economic knowledge. The same is true of Piketty’s *Capital and Ideology* (see Piketty, 2020a, p. 455).</footnote>

<footnote n="76">⁷⁶ On the early history of the *NBER*, see Fogel & al (2012, pp. 21-48).</footnote>
seen as “a global public good” (WIR 2022, pp. 10, 23). They constitute a fundamental element
for feeding the permanent social and democratic deliberations about social justice and the ideal
level of inequality (Piketty, 2020). For Piketty, Saez, and Zucman, “the primary goal of
inequality analysis should be to illuminate the public debate on economic justice” (Piketty, Saez
and Zucman, 2022), or in other words to help citizens and legislators or policymakers to do
more enlightened choices about the distribution of income and wealth.

But we think that the members of the WIL share more than that with Fisher. Indeed, in this
speech untitled “Economists in public service” Fisher offers a deep and general reflection of
the role of the economist in society, who is seen as “a guide, counsellor, and friend of
humanity”, trying to serve democracy and “all humanity throughout the world and throughout
future generations.” (Fisher, 1919, pp. 5, 11, 21) Fisher asks for economists to get involved in
public debate and the policy world, performing this task with “wisdom, unselfishness, and
impartiality” (ibid., 21; see also p. 11 his analogy with the figure of the judge). And in the same
texts he makes several concrete policy proposals to reduce inequalities of income and wealth,
pleading for more taxation of inheritance and for economic democracy (ibid., pp. 11-14).

Likewise, members of the inequality school, and especially their main public figures like
Piketty, Zucman, Chancel and Cage, see economics as *an engaged science*. Some of them
exhibit a clear willingness to have an influence, outside academia, on public opinion and policy-
making regarding inequality and tax justice. In a way, the inequality school might be seen as a
*lobbying group*,<sup>77</sup> relentlessly pleading for more equality, redistribution, tax justice, and more
specifically, as we noticed, for wealth tax. They believe in the power of ideas to change the
world, seeing history as the struggle of ideologies (see Piketty, 2019). They engage in the battle
of ideas with their works, but also through signing public tribunes<sup>78</sup> and even more importantly

<footnote n="77"><sup>77</sup> We thank Justine Loulergue for having suggested this idea.</footnote>

<footnote n="78">⁷⁸ For example, Piketty, Chancel and Zucman signed a tribune for *Le Monde* (a famous French daily newspaper, of which Julia Cage is the president of the readers’ society) on July 20, 2023 untitled «Les inégalités compromettent tous nos objectifs sociaux et environnementaux”: lettre au secrétaire général de l’ONU et au président de la Banque mondiale (“Inequality undermines all our social and environmental objectives”: letter to the UN General Secretary and the President of the World Bank”): https://www.icrict.com/press-release/2023/3/20/icrict-letter-to-united-nations-secretary-general-antnio-guterres</footnote>

<footnote>They signed another one in the same journal on October 10, 2023 in association with a *European Citizens' Initiative* untitled « Tax the Rich », asking the European Commission to create a European tax on great wealth to finance the ecological and social transition: See https://www.lemonde.fr/idees/article/2023/10/10/pour-lutter-contre-le-changement-climatique-et-les-inegalites-nous-appelons-a-la-creation-d-un-impot-europeen-sur-la-grande-fortune_6193535_3232.html and
https://www.tax-the-rich.eu/</footnote>

<footnote>A third example is a text untitled “For a just and democratic climate transition” signed by Cage, Chancel and Piketty and published on the website of *Social Europe*:</footnote>
through their engagement in political campaigns, advising and/or supporting left-wing
candidates. For example, Saez and Zucman discussed with different candidates of the US
Democratic Party like Bernie Sanders, Hillary Clinton and Elizabeth Warren during their
presidential campaigns about the introduction of a wealth tax in the USA, though only the latter
eventually retained the idea and defended it.<fnref n="79" /> In 2024, Zucman, who is a member with Piketty
of the *Independent Commission for the Reform of International Corporate Taxation* and the
President of the *EUTO*<fnref n="80" /> (allied with the NGO *Tax Justice Network*), made intense work and
lobbying among world political leaders at the G20 to implement a wealth tax on the ultra-
wealthy worldwide.<fnref n="81" /> Though nothing has been decided yet, his efforts were not in vain since
G20 countries have agreed for the first time to cooperate to tax better the ultra-wealthy, but
Trump's reelection might threaten that process of international cooperation. Zucman's reluctant
plea for taxing the ultra-wealthy also recently found some echo in his home country. Indeed,
the now so-called "Zucman tax", a minimum tax of 2% on the wealth of very rich people
(defined here as those whose wealth is over 100 million euros), was adopted in a mixed
commission on February 13 2025 and then submitted to the vote of the Parliament one week
later and adopted by the National Assembly, following a bill proposed by the Ecological and
Social Group and supported by Clémentine Autain and Eva Sas. But the text was rejected by
the Senate, dominated by the right, on June, 12 2025. Yet, the Zucman tax made a comeback in
French politics in September 2025 with the need to find a majority coalition to vote the 2026
budget and with the rise of public debt, and it became the hot topic of the day in public debate,
with Zucman defending his proposal in French media and through the publication at the end of
October of a short essay, a tract, published in French by Le Seuil (Zucman, 2025).<fnref n="82" />

As for Piketty, even though he has never been a member of the French Socialist Party, he and
Cage advised its official candidate, Benoît Hamon, during the 2017 French Presidential
campaign<fnref n="83" /> More recently, Cage, Piketty, Saez, Zucman, Chancel and Landais signed a tribune

<footnote><https://www.socialeurope.eu/for-a-just-and-democratic-climate-transition?fbclid=IwAR3F0Hntd7pMa5u6-DDB6Bji9uesqYClfXSH6nFkX6A1ZgFOe8oL9iF4kT0></footnote>

<footnote n="79">⁷⁹ See: https://www.newyorker.com/news/the-political-scene/the-french-economist-who-helped-invent-elizabeth-warrens-wealth-tax</footnote>

<footnote n="80">⁸⁰ It is interesting to note that besides Zucman, the *EUTO* has Policy Advisors and a Policy Director who try to promote the work of the Observatory and its policy recommendations among policymakers and the media.</footnote>

<footnote n="81">⁸¹ See his concrete proposal here: https://gabriel-zucman.eu/files/report-g20.pdf</footnote>

<footnote n="82">⁸² This essay/tract is published in the 'Libelle' collection of Le Seuil, in which Piketty published in 2022 a tract entitled *Mesurer le racism, vaincre les discriminations* (see Piketty 2022b).</footnote>

<footnote n="83">⁸³ Piketty has also been a member of the British Labour Economic Advisory Council in 2015-2016, advising Jeremy Corbyn, but he quickly resigned because of work commitments and disagreements about Europe: https://www.theguardian.com/politics/2016/jun/29/thomas-piketty-quits-as-adviser-to-jeremy-corbyn</footnote>
gathering 300 economists and supporting the program of the *Nouveau Front Populaire* (“New Popular Front”, an alliance of left-wing, including green parties in France) for the 2024 legislative elections.<fnref n="84" /> Public and political engagement seems to be in the DNA of the leaders of the inequality school.

**Conclusion:**

In this paper, we first tried to state the emergence and rise in the 21st century of an ever-growing International Research Network On Inequality (IRNOI) in economics working at or collaborating with the WIL, hosted at PSE, and whose leaders are Thomas Piketty, Emmanuel Saez, Facundo Alvaredo, Gabriel Zucman and Lucas Chancel. We then showed that the members of this IRNOI, and in particular the (present and past) members of the WIL in the strict sense, share much more than an interest in inequality and their historical data. We identified their common vision of inequality, their methodology, their policy proposals and their values or ideology, as well as their view of economics as a social, political and moral science. We therefore believe that they constitute an emerging school of economic thought, which we call the “inequality school”, with a singular approach to economics and making significant contributions to it by providing more and more data on inequality all around the world and over a longer time period, and by developing DINA, a revolution in national accounts.

The leading figures of the IRNOI of the WIL have already won several important prizes and distinctions over the years for their contributions to economic science, among which the French « prix du meilleur jeune économiste » (best young economist award) awarded by “Le Monde” and the “Cercle des économistes” to a French economist under 41 who combines expertise and active participation in public debate. This prize was won by Piketty in 2002, Saez in 2010, Landais in 2016, Zucman in 2018 and Cage in 2023. Piketty and Cage also won the Yrjö-Jahnsson Award of the *European Economic Association* (the former in 2013, the latter in 2025). More importantly, Saez and Zucman won the “John Bates Clark Medal” (the former in 2009 and the latter in 2023), one of the most esteemed prizes in economics,<fnref n="85" /> and often a good

<footnote>More recently, Julia Cage has been approached by *La France Insoumise* (a French left-wing party led by Jean-Luc Mélenchon) to be on their list for the 2024 European elections but she refused, pleading for a common list among French left-wing parties: https://www.liberation.fr/politique/la-france-insoumise-a-tente-de-recruter-julia-cage-pour-les-europeennes-20240307_FRCTS7EOLFASROHB7AN5HGZYGA/</footnote>

<footnote n="84">⁸⁴ https://www.nouvelobs.com/politique/20240625.OBS90197/les-orientations-economiques-du-nouveau-front-populaire-repondent-aux-defis-de-notre-epoque.html</footnote>

<footnote n="85">⁸⁵ The John Bates Clark was also won by Stefanie Stantcheva, who worked with Piketty and Saez on optimal taxation theory and a *WID* fellow, in 2025.</footnote>
predictor of the most prestigious of all, the Nobel Prize in Economics,<fnref n="86" /> of which Piketty, Saez and Zucman are often seen as potential winners, as was their mentor, Anthony Atkinson (especially in 2015 when Angus Deaton was awarded).<fnref n="87" /> Moreover, the WIL is now a leading research centre on inequality, along with *UNU-WIDER* (United Nations University World Institute for Development Economics Research) hosting the *WIID* (World Income Inequality Database), the *Stone Center on Socio-Economic Inequality at the City University of New York*, and the *International Inequalities Institute* of the *London School of Economics and Political Science*.

The origin of the school of inequality can be traced back to Piketty's first book on the history of (economic) inequality and top incomes in France in the 20th century, on which he began to work in 1998 and which was published in 2001. He then quickly became the leader of a research program built upon an ever-growing network of scholars working on inequality and its history all around the globe, which allowed him to write his highly successful and influential book, *Capital in the 21st Century*. Piketty's book is the result of the creation and early phase of development of the school, rather than its starting point, as one could believe at first sight. Inside the school, we tried to make a distinction between an “inner circle” and a “wider circle”. As we see it, the former is made up of Alvaredo, Chancel, Saez and Zucman, whose intellectual itinerary and works are quite connected to Piketty and to each other's works, as our quantitative analysis of co-authorship and citation confirms. To the exception of Saez, all of them have completed their PhD under the supervision of Piketty and can be seen as his “followers” or “heirs”. They have now their own doctoral students working on inequality within the WIL and perpetuating the research program. Zucman even launched its own research institution focused on taxation, the *EUTO*, whose members are also often affiliated with the WIL. The “wider circle” constitutes a global and ever-growing network of researchers either working for the WIL (including many young scholars working on their PhD thesis under the supervision of one the members of the inner circle), the heart of the school, or collaborating with it as WID fellows. The worldwide research program on economic inequality launched by Piketty and his close collaborators, with the early help of Atkinson, is end-to-end a collective and cooperative process whose aim is to provide a global and comparative history of inequality and to give an open access to economic data to the public, or in other words to enlighten citizens about

<footnote n="86">⁸⁶ More precisely “The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel”. Note that Abhijit Banerjee, who was one of the first collaborators of the IRNOI and who is a WID Fellow, won the Nobel Prize in 2019, though not for his works on inequality.</footnote>

<footnote n="87">⁸⁷ On the history of the John Bates Clark Medal and its empirical turn, see Cherrier and Svorencik (2020),</footnote>
inequalities of income and wealth to help them make well-informed choices about taxation and redistribution. More generally, it seems that in the eyes of the members of the inequality school, and especially of its leader, Thomas Piketty, a better measurement and knowledge of inequality is essential for raising public awareness, motivating action, and designing good (egalitarian) public policies, but maybe too for estimating progress and holding political leaders accountable for reaching goals (in terms of inclusive growth and of reducing inequality), as can be the case with the measurement of poverty, to which Atkinson was devoting his last efforts (Atkinson, 2019).

Finally, the emergence and rise of the inequality school inside economics might be seen as the result, or as a new illustration of the applied and empirical turn in economics,<fnref n="88" /> and of the growing possibilities offered by the progress in information technologies and data analysis (Piketty, 2014, pp. 19-20),<fnref n="89" /> as well as of the necessity of an interdisciplinary perspective on economic issues, putting economics back at the heart of social sciences. It is also a product of economic history, of the increasing within-country economic inequality since the 1980s, for which we lacked data and historical perspective, and of the 2008 financial crisis, which might have been a turning point.<fnref n="90" /> Last but not least, the ever more pressing issue of climate change with significant inequalities of carbon emissions inside and between countries, which are correlated with inequalities of income (and wealth), and on which members of the inequality school are now working (see WIR 2022, chap 6; Chancel, 2022; Chancel & al, 2023b, Chancel & al, 2025), should make of economic inequality a key issue for economists for the years and decades to come, opening a bright future for the inequality school.<fnref n="91" />

## References

Aaberge R., Bourguignon F., Brandolini A., Ferreira F., Gornick J., Hills J., Jantti M., Jenkins S., Marlier R., Micklewright J., Nolan B., Piketty T., Radermacher W., Smeeding T. 2017. Tony Atkinson and His Legacy, *The Review of Income and Wealth*, vol 63, n°3), 412-444.

<footnote n="88">⁸⁸ On the “applied” turn in economics, see Backhouse and Cherrier (2017a). On the empirical turn, see Hamermesh (2013).</footnote>

<footnote n="89">⁸⁹ On the impact of the “data revolution” on economics, see Einav and Levin (2013). On the role of the development of computers see Backhouse and Cherrier (2017b).</footnote>

<footnote n="90">⁹⁰ For a similar point of view, see Milanovic (2023, pp. 287-88).</footnote>

<footnote n="91">⁹¹ For more arguments supporting the idea that inequality is likely to be a key issue for economists in the years to come, and on the role that international institutions could play on that front, see section 3 of Ferreira (2022).</footnote>
Allen, R. 2019. Class structure and inequality during the industrial revolution: lessons from England's social tables, 1688–1867, *The Economic History Review*, vol 72, n°1, 88-125.

Alstadsæter, A., Godar, S., Nicolaides, P., Zucman, G. 2024. *Global Tax Evasion Report*, EU Tax Observatory.

Alvaredo, F., Chancel, L., Piketty, T., Saez, E. & Zucman, G. 2017. *World Inequality Report 2018*, World Inequality Lab wir2018.wid.world

Alvaredo, F., Chancel, L., Piketty, T., Saez, E. & Zucman, G. 2020. Towards a System of Distributional National Accounts: Methods and Global Inequality Estimates from WID.world, *Economie et Statistique / Economics and Statistics*, n°517-518-519, 41–59.

Alvaredo, F., De Rosa M., Flores I. and Morgan, M., “The Inequality (or the Growth) we Measure: Data Gaps and the Distribution of Incomes”, World Inequality Lab – Working Paper n° 2022/07, 1-38.

Alvaredo, F. and Garcia-Penalosa, C. 2018. Top incomes, wealth and inheritance: special issue in homage to Tony Atkinson, *Journal of Economic Inequality*, vol 16, 131-136.

Atkinson, A. 1970. On the measurement of economic inequality, *Journal of Economic Theory*, vol 2, n°3, 244-263.

Atkinson, A. 1971. The Distribution of Wealth and the Individual Life-Cycle, *Oxford Economic Journal*, vol 23, n°2, July 1971, 239-254.

Atkinson, A. 1972. *Unequal Shares: Wealth in Britain*, London, Allen Lane, The Penguin Press.

Atkinson, A. 1973. How Progressive Should Income Tax Be?, pp. 90-109 in *in Parkin, M (ed.) Essays in Modern Economics*, London, Longman.

Atkinson, A. 1997. Bringing income distribution in from the cold, *The Economic Journal*, vol 107 (March 1997), 297-321.

Atkinson, A. 2015. *Inequality. What Can be Done?* Cambridge, MS, Harvard University Press.

Atkinson, A. 2019. *Measuring Poverty Around the World*, Princeton, Princeton University Press.

Atkinson, A. and Bourguignon, F. 2015. *Handbook of Income Distribution*, Vol 2B, Amsterdam, North Holland.
Atkinson, A. and Harrison, A. 1974. Wealth Distribution and Investment Income in Britain, *The Review of Income and Wealth*, June 1974, vol 20, n°2, 125-142.

Atkinson, A. and Harrison, A. 1978. *The Distribution of Personal Wealth in Britain*, Cambridge, Cambridge University Press.

Atkinson, A. and Piketty, T. (eds). 2007. *Top Incomes over the Twentieth Century*, Oxford, Oxford University Press.

Atkinson, A. and Piketty, T. (eds). 2010. *Top Incomes: A Global Perspective*, Oxford, Oxford University Press.

Atkinson, Anthony B., Rainwater, Lee, Smeeding, Timothy M. 1995. *Income Distribution in OECD Countries: Evidence from the Luxembourg Income Study*. OECD, Paris and Washington D.C.

Atkinson, A. and Stiglitz, J. 1972. The Distribution of Wealth and the Individual Life-Cycle, *Oxford Economic Journal*, vol 23, n°2, July 1971, 239-254.

Atkinson, A. and Stiglitz, J. 1976. The design of tax structure: direct versus indirect taxation, *Journal of Public Economics*, vol 6, 55-75.

Auten, G. and Splinter, D. 2024a. Income Inequality in the United States: Using Tax Data to Measure Long-Term Trends, *Journal of Political Economy*, vol 132, n°7, 2179-227.

Auten, G. and Splinter, D. 2024b. Reply to Piketty, Saez, and Zucman (2024): Income Inequality in the United States., Unpublished.

Backhouse, R. and Cherrier, B. 2017a. The Age of the Applied Economist: The Transformation of Economics since the 1970s, *History of Political Economy*, vol 49, 1-33.

Backhouse, R. and B. Cherrier 2017b, 'It's Computers, Stupid!' The Spread of Computers and the Changing Roles of Theoretical and Applied Economics, *History of Political Economy*, vol 49 (annual suppl), 103-129.

Benest, S. 2024a. From Social to Mathematical Science: Transforming Economics at the École des Hautes Études en Sciences Sociales, 1956-85, *History of Political Economy*, vol 54, n°2, 181-215.

Benest, S. 2024b. Cash Is Not King. Patrons and Economics at the École des hautes études en sciences sociales, 1947-1957, *Revue d'histoire des sciences humaines*, vol 45, 19-42.
Bharti, N., Chancel, L., Piketty, T. and Somanchi, A. 2024. Towards Tax Justice and Wealth Redistribution in India: Proposals based on latest Inequality Estimates, WIL Issue Brief 2024/01.

Blanchet, T., Chancel, L. and A. Gethin, A. 2022. Why is Europe More Equal than the United States?", *American Economic Journal: Applied Economics*, vol 14, n°4, 480-518.

Blanchet, T., Saez, E. and Zucman, G. 2022. Real Time Inequality, NBER Working Paper 30229.

Bothe P., Chancel, L., Gethin, A., Mohren, C. 2025. Global Income Inequality by 2050: Convergence, Redistribution, and Climate Change, World Inequality Lab Working Paper 2025/09.

Bourguignon, F. 2012. *La mondialisation de l'inégalité*, Paris, Seuil.

Boushey, H. 2013. A (Longer) Interview with Robert M. Solow, Washington, DC: Washington Center for Equitable Growth. Accessed at: http://equitablegrowth.org/work/a-longer-interview-with-robert-m-solow

Boushey, H. 2019. *Unbound How Inequality Constricts Our Economy and What We Can Do about It*, Cambridge, MS, Harvard University Press.

Boushey, H. 2020. Unbound: Releasing Inequality's Grip on Our Economy, *Review of Radical Political Economics*, vol 52, n°4, 597-609.

Boyer, R. 2013. Capital in the Twenty-First Century: A *régulationist* view, *Revue de la régulation* [En ligne], 14 | 2e semestre / Autumn 2013, mis en ligne le 04 juin 2014. URL : http://journals.openedition.org/regulation/10618

Brissaud, C. and Chahsiche, J-M. 2017. How to Become an International Intellectual? The Case of Thomas Piketty and “Capital in the Twenty-First Century”, *Sociologica*, vol 1-2017, 1-38.

Broome, J. 2008. Why Economics needs Ethical Theory, pp. 7-14 in Basu, K., and Kanbur, R. (ed.) *Arguments for A Better World: Essays in Honor of Amartya Sen: Volume I: Ethics, Welfare, and Measurement*, Oxford, Oxford University Press.

Cage, J. and Piketty, T. 2023. *Une histoire du conflit politique. Elections et inégalités sociales en France 1789-2022*, Le Seuil, Paris.
Chancel, L. 2022. Global Carbon Inequality over 1990-2019, *Nature Sustainability*, online 29 September 2022.

Chancel, L. 2025. *Energies et inégalités : une histoire politique*, Seuil, Paris.

Chancel, L., Bothe, P. and Voiturier, T. 2023a. The potential of wealth taxation to address the triple climate inequality crisis, *Nature Climate Change*, vol 1-3, published online 29 December 2023.

Chancel, L., Bothe, P. and Voituriez, T. 2023b. *Climate Inequality Report 2023. Fair Taxes for a Sustainable Future in the Global South*, World Inequality Lab Study 2023/1.

Chancel, L., Gómez-Carrera, R., Moshrif, R., Piketty, T., et al. World Inequality Report 2026, World Inequality Lab. wir2026.wid.world

Chancel, L., Mohren, C., Bothe, P., Muti, S., Villaverde, P. 2025. *Climate Inequality Report 2025. Climate Change: A Capital Challenge. Why Climate Policy Must Tackle Ownership.* World Inequality Lab Key Report, 2025.

Chancel, L., Piketty, T., Saez, E. and Zucman, G. 2021. *World Inequality Report 2022*, World Inequality Lab wir2022.wid.world.

Cherrier, B. and Svorencik, A. 2020. Defining Excellence: 70 Years of John Bates Clark Medal, *Journal of the History of Economic Thought*, vol 42 n°2, 153-176

Clarke, C. and Kopczuk, W. 2025. Measuring Income and Income Inequality, *Journal of Economic Perspective*, vol 39 n°2, 103-126.

Cook, E. 2019. Historicizing Piketty, pp. 35-57 in C.O. Christiansen, C.O and Jensen, S.L.B (eds.), *Histories of Global Inequality*, Palgrave Macmillan.

Davis, J. 2024. Stratification economics: Historical Origins and Theoretical Foundations, *Oxford Review of Economic Policy*, vol 43, n°4, 475-85.

Dherbécourt, C., Fack, G., Landais, C. and Stantcheva, S. 2021. Repenser l'héritage, Les notes du conseil d'analyse économique, n°69, 1-12 : [Repenser l'héritage - Conseil d'Analyse Economique](https://www.creterla.org/repenser-l-heritage)

Einav, L. and Levin, J.D. 2013. The Data Revolution and Economic Analysis, NBER WP 19035, 1-28.
Ferreira, F. (2022), The analysis of inequality in the Bretton Woods Institutions, International Inequalities Institute, Working Paper 83, 1-29.

Ferreira, F. 2023. Is There a ‘New Consensus’ on Inequality?, LSE III Working Paper 101, 1-24.

Fisher, I. 1919. Economists in Public Service: Annual Address of the President, *The American Economic Review*, Vol. 9, No. 1, Supplement, Papers and Proceedings of the Thirty-First Annual Meeting of the American Economic Association (Mar., 1919), 5-21.

Fisher-Post, M. and Gethin, A. 2023. Government Redistribution and Development. Global Estimates of Tax-and-Transfer Progressivity, 1980-2019, WIL Working Paper N°2023/17, 1-102.

Fogel, R., Fogel, E., Guglielmo, M. and Grotte, N. 2013. *Political Arithmetic: Simon Kuznets and the Empirical Tradition in Economics*, Chicago, Chicago University Press.

Forget, E. and Goodwin, C. 2011. Intellectual Communities in the History of Economics, History of Political Economy, vol 43, n°1, 1-24.

Frankel, S. H. & Herzfeld, H. (1943) "European income distribution in the Union of South Africa and the effect thereon of income taxation", *South African Journal of Economics*, vol 11, n°2, 121-136.

Garbinti, B., Goupille-Lebret, J. & Piketty, T. 2018. Inequality Dynamics in France, 1900-2014: Evidence from Distributional National Accounts (DINA), *Journal of Public Economics*, vol 162, 63-77.

Geison, G. L. 1981. Scientific Change, Emerging Specialties, and Research Schools, *History of Science*, vol. 19, pt. 1, no. 43, 20-40.

Gethin, A., Martinez-Toledano, C. and Piketty, T. (dir.). 2021. *Clivages politiques et inégalités sociales. Une étude de 50 démocraties (1948-2020)*, Paris, EHESS/Gallimard/Seuil.

Govind. Y., Santini, P., Derenoncourt. E. 2025. Racial Inequality in France, World Inequality Lab Working Paper 2025/23.

Hamermesh, D. 2013. Six Decades of Academic Publishing. Who and How?, *Journal of Economic Literature*, vol 51, n°1, 162-172.
Heckman, J. and S. Moktan, S. 2020. Publishing and promotion in economics: the tyranny of the top five, *Journal of Economic Literature*, vol 58, 419-470.

Houser, O., and Norton, M. 2017. (Mis)perceptions of Inequality, *Current Opinion in Psychology*, vol 18, 21-25.

Kleven, H. and Luttmer, E. 2018. A special issue of the Journal of Public Economics: Honoring the work of Sir Anthony B. Atkinson (1944–2017), *Journal of Public Economics*, 162, 1-3.

Kuznets, S. 1951. Government Product and National Income, *Review of Income and Wealth*, vol 1, 178-244.

Kuznets, S. 1955. Economic Growth and Economic Inequality, *The American Economic Review*, vol 45, n°1, 1-28.

Kuznets, S., Epstein, L. and Jenks, E. (1941). National Income and Its Composition, 1919-1938, Volume I. National Bureau of Economic Research.

Landais, C., Piketty, T. and Saez, E. 2011. *Pour une révolution fiscale. Un impôt sur le revenu pour le XXIe siècle*, Paris, Seuil.

Lari, T. 2021. When does complementarity support pluralism about schools of economic thought?, *Journal of Economic Methodology*, vol 28, n°3, 322-335.

Lindert, P. and Williamson, J. 1982. Revising England's Social Tables 1688-1812, *Explorations in Economic History*, vol 19, 385-408.

Lucas, R. 2004. The Industrial Revolution: Past and Future. 2003 Annual Report Essay of the Federal Reserve Bank of Minneapolis.

Milanovic, B. 2016. *Global Inequality. A New Approach for the Age of Globalization*, Cambridge MA, Harvard University Press.

Milanovic, B. 2023. *Visions of Inequality*, Cambridge, MS, The Belknap Press of Harvard University Press.

Moran, T. (2005), Kuznets's Inverted U-Curve Hypothesis: The Rise, Demise, and Continued Relevance of a Socioeconomic Law, *Sociological forum*, vol 20, n°2, 209-244.

Morrell, J. B. 1972. The Chemist Breeders: The Research Schools of Liebig and Thomas Thomson, *Ambix*, vol 19, 1-46.
Muller, B. 2021. De la formation d'un concept à l'invention d'une tradition: les avatars de l'histoire sérielle, In Crouzet, D. and Hugon, A. (eds) *Un historien dans ses lendemains : Pierre Chaunu*, Caen, Presses universitaires de Caen, https://doi.org/10.4000/books.puc.15437.

Naidu S., D. Rodrik, D. and Zucman, G. 2020. Economics after Neoliberalism: introducing the *EIFP* project, *AER Papers and Proceedings*, vol 110, 366-371.

Negru, I. 2013. Revisiting the Concept of Schools of Thought in Economics: The Example of the Austrian School, *The American Journal of Economics and Sociology*, vol 72, n°4, 983-1008.

Nievas, G. and Piketty, T. 2025. Unequal Exchange and North-South Relations: Evidence from Global Trade Flows and the World Balance of Payments 1800-2025, World Inequality Lab Working Paper 2025/11.

O'Connor, A. 2020. When Measurements Matter: Poverty, Wealth, and the Politics of Inequality in the United States, *History of Political Economy*, vol 52, n°3, 589-607.

Okun, A. [2015]1977. *Equality and Efficiency*. The Big Tradeoff, Washington DC, Brookings Institution Press.

Pemberton, J. and Piketty, T. 2020. *Le capital au XXIe siècle* [documentary]. General Film Corporation, Upside Production.

Piketty, T. 2001. *Les hauts revenus en France au XXe siècle. Inégalités et redistributions (1901-1998)*, Paris, Grasset.

Piketty, T. 2014. *Capital in the 21st Century*, Cambridge, MS, Harvard University Press, first published in French in 2013, *Le capital au XXIe siècle*, Paris, Seuil.

Piketty, T. 2015. Vers une économie politique et historique, *Annales: Histoire, Sciences Sociales*, janvier-mars 2015, n°1, 125-138.

Piketty, T. 2018. Tony Atkinson: The birth and development of modern inequality studies, *The Economic and Labour Relations Review*, Vol 29, n°1, 41-43.

Piketty, T. 2020. *Capital and Ideology*, Cambridge, MS, Harvard University Press, first published in French in 2019, *Capital et idéologie*, Paris, Seuil.

Piketty, T. 2021. Capital et idéologie : éléments pour une histoire des régimes inégalitaires, *Revue d'histoire moderne et contemporaine*, vol 68, n°4, 67-70.
Piketty, T. 2022a. *A Brief History of Equality*, Cambridge MA: Harvard University Press, first published in French in 2021, *Une brève histoire de l'égalité*, Paris, Seuil.

Piketty, T. 2022b. *Mesurer le racisme, vaincre les discriminations*. Paris, Seuil.

Piketty, T. 2023. *Nature, culture et inégalités. Une perspective comparative et historique*, Société d'ethnologie, Nanterre.

Piketty, T., Labrousse, A., Montalban, M., Da Silva, N. 2020. Pour une économie politique et historique : autour de *Capital et Idéologie, Revue de la régulation*, vol 28 | 2nd semestre / Autumn 2020, mis en ligne le 31 décembre 2020, consulté le 03 avril 2025. URL : http://journals.openedition.org/regulation/18316

Piketty, T. and Saez, E. 2003. Income inequality in the United States, 1913-1998, *Quarterly journal of economics*, vol. 118, no 1, 1-39.

Piketty, T. and Sandel, M. 2025. *Equality. What it means and why it matters*, Polity Press, Cambridge UK.

Piketty, T, Saez, E. and Zucman, G. 2018. Distributional National Accounts: Methods and Estimates for the United States, *The Quarterly Journal of Economics*, vol 133, n°2, 553-609.

Piketty, T., Saez, E. and Zucman, G. 2022. Twenty Years and Counting: Thoughts about Measuring the Upper Tail, *Journal of Economic Inequality*, vol 20, n°1, 255-264.

Piketty, T., Saez, E. and Zucman, G. 2023. Rethinking Capital and Wealth Taxation, *Oxford Review of Economic Policy*, vol 39, n°3, 575-591.

Piketty, T, Saez, E. and Zucman, G. 2024. Income Inequality in the United States: A Comment, Unpublished.

Priem, J., Piwowar, H., & Orr, R. (2022). *OpenAlex: A fully-open index of scholarly works, authors, venues, institutions, and concepts* (arXiv:2205.01833). arXiv. https://doi.org/10.48550/arXiv.2205.01833

Procopovitch, S.N. 1926. The Distribution of National Income, *The Economic Journal*, vol 36, n°141, 69-82.

Ramos Pinto, P. and Paidipaty, P. 2020. Introduction: Measuring Matters, *History of Political Economy*, vol 52, n°3, 413-34.
Ranaldi, Marco. 2022. "Income Composition Inequality", *Review of Income and Wealth*, 68(1), 139-60.

Ranaldi, Marco. 2025. "**Compositional Inequality: Measurement, Stylized Facts, and Theoretical Aspects**", *Review of Political Economy*, pre-publication online 01 May 2025, **1-32**.

Reddy, S. 2020. Afterword: Inequality, A Guide for the Reflexive, *History of Political Economy*, vol 52, n°3, 609-19.

Robbins, L. 1981. Economics and Political Economy, *The American Economic Review*, May, 1981, Vol. 71, No. 2, Papers and Proceedings of the Ninety-Third Annual Meeting of the American Economic Association (May, 1981), 1-10.

Rutherford, M. 2005. 'Who is afraid of Arthur Burns?' The NBER and the foundations, *Journal of the History of Economic Thought*, vol 27, n°2, 109-39.

Saez, E. 2017. The Research Agenda Post-'Capital in the 21st Century', pp. 304-21 in Boushey, H., De Long, B. and Steinbaum, M. (eds) *After Piketty. The Agenda for Economics and Inequality*, Cambridge, MS, Harvard University Press.

Saez, E. 2021. Should We Tax Wealth?, pp. 153-59 in Blanchard, O. and Rodrik, D. (eds) *Combating Inequality*, Cambridge, MS, MIT Press.

Saez, E. 2024. Gabriel Zucman: Winner of the 2023 Clark Medal, *Journal of Economic Perspectives*, vol 38, n°2, 227-244.

Saez, E. and Zucman, G. 2019. *The Triumph of Injustice. How the Rich dodge Taxes and How to Make Them Pay*, WW Norton & Company.

Saez, E. and Zucman, G. 2020. The Rise of Income and Wealth Inequality in America: Evidence from Distributional Macroeconomic Accounts, *Journal of Economic Perspectives*, vol 34, n°4, Fall 2020, 3-26.

Saez, E. and Zucman, G. 2022. Wealth Taxation: Lessons from History and Recent Developments, *American Economic Association: P&P*, vol. 112, 58-62.

Sandmo, Agnar. 2015. The Principal Problem in Political Economy: Income Distribution in the History of Economic Thought, pp. 3-65 in Atkinson, A. and Bourguignon, F. (eds) *Handbook of Income Distribution*, vol 2, Amsterdam, North Holland.
Sandmo, Agnar. 2022. Tony Atkinson 1944–2017: A lifetime commitment to the study of inequality, *The European Journal of the History of Economic Thought*, vol 24, n°3, 612-628.

Stiglitz, J. 2012. *The Price of Inequality*, New York, WW Norton and Company.

Temin, P. 2014. The Rise and Fall of Economic History at MIT, *History of Political Economy*, vol 46, 337-350.

Tomlinson, J. 2020. Social Democracy and the Problem of Equality: Economic Analysis and Political Argument in the United Kingdom, *History of Political Economy*, vol 52, n°3, 519-538.

Topalov, C. 1999. (dir) *Laboratoires du nouveau siècle. La nébuleuse réformatrice et ses réseaux en France (1880-1914)*, Paris, Editions de l'EHESS.

Truc, A., Santerre, O., Gingras, Y., and Claveau, F. 2023. The Interdisciplinarity of Economics, *Cambridge Journal of Economics*, vol 47, 1057-1086.

Walraevens, B. 2021. Adam Smith's view of economic inequality, *Cambridge Journal of Economics*, vol 45, n°1, 209-224.

Walraevens, B. 2023. Rawls's Maximin and Optimal Taxation Theory, *European Journal of the History of Economic Thought*, vol 30, n°5, 860-882.

Wright, J. 2024. The hierarchy in economics and its implications, *Economics and Philosophy*, vol 40, 257-78.

Zucman, G. 2013. *La Richesse Cachée des Nations : Enquête sur les Paradis Fiscaux*. 2013. Paris, Le Seuil.

Zucman, G. 2014. Taxing across Borders: Tracking Personal Wealth and Corporate Profits, *Journal of Economic Perspectives*, vol 28, n°4, 121-148.

Zucman, G. 2021. Can a Wealth Tax Work?, pp. 271-75 in Blanchard, O. and Rodrik, D. (eds) *Combating Inequality*, Cambridge, MS, MIT Press.

Zucman, G. 2025. *Les milliardaires ne paient pas d'impôt sur le revenu et nous allons y mettre fin*, Paris, Le Seuil.

## Appendix

Methodology for bibliometric data collection.
We followed these steps in order to build a dataset for analyzing co-authorship relations:

a) We consulted the WID (https://wid.world/team/) and WIL (https://inequalitylab.world/en/team/) websites to identify all WID Fellows and WIL members on 28/08/2025. We excluded from this list the few affiliates that did not hold a research position. The complete list is available in Table A.1 below.

b) For all identified authors, we searched in OpenAlex's Author API and collected a list of ids. We applied this strategy instead of searching for a specific author id (like "A5026928510", which is the main id for Thomas Piketty) because occasionally some works are not correctly linked to an existing author id so that another author id is created for what remains the exact same person. Searching for a name within the author API thus enables to broaden the scope of the data collection.

c) We scrutinized this list of ids to remove authors that are clearly not the ones we are interested in. Indeed, for some authors whose name are rather common the fetched list of ids may be particularly long (e.g: the list of ids for "Carlos Oliveira" contains 1702 items). Specifically, we eye-balled the full list of fetched ids, compared the fetched names and affiliations with the ones listed in the WIL or WID websites (plus some additional targeted web searches) and removed ids that did not match.

d) From the corrected list of ids, we collected all works associated with each id using OpenAlex's Works API.

e) We removed all works which were duplicates in terms of doi or in terms of title + list of authors. However, since these works which we consider as identical could have been cited on their own, we preserved the information on references within our dataset by adding the citation count to the ones of the preserved documents.

f) We restrict our attention to articles, books, book chapters and reports. Furthermore, since the WIL and WID were created in 2015, we consider only works published in 2015 or after for members of the WIL and WID Fellows.

For citation analysis, we took the additional following steps:

g) For each author or group of authors we constructed a list of all works that are cited by this author/group.

h) We fetched all cited works using OpenAlex's Works API.

i) Again we removed duplicates and limit our attention to research types of documents.

From the 219 WID Fellows that we identified, 27 are members of the WIL (among which the 5 members of what we call the "inner circle" of the inequality school). The above procedure allows for the identification of 192 authors in the OpenAlex database. We thus could not fetch bibliometric information for 27 scholars, among which 7 members of the WIL. Among these, 16 (including 5 members of the WIL) are at the very beginning of their academic career (mostly PhD students or research assistants). It is thus likely that these scholars simply did not have any publication yet. For the remaining 11, we often find ids that match the names. However, screening based on names + affiliations does not allow to identify with precision which ids are correct. For instance, none of the found ids matches the affiliation that is listed on the WID website, nor matches the affiliations that
we could find on members' personal pages (when available), nor includes "Paris School of Economics" (which is the most frequent affiliation of WID Fellows).

<table><caption>Table A.1: WID Team according to WID website (https://wid.world/team/) consulted on the 28/08/2025</caption><thead><tr><td>NOM</td><td>PRENOM</td><td>WIL</td><td>IC</td><td>Missing</td></tr></thead><tbody><tr><td>AABERGE</td><td>ROLF</td><td>X</td><td></td><td></td></tr><tr><td>ABDUL KHALID</td><td>MUHAMMED</td><td></td><td></td><td></td></tr><tr><td>ABOOBAKER</td><td>ADAM</td><td></td><td></td><td></td></tr><tr><td>ACCIARI</td><td>PAOLO</td><td></td><td></td><td></td></tr><tr><td>ADVANI</td><td>ARUN</td><td></td><td></td><td></td></tr><tr><td>AGARWAL</td><td>SUMIT</td><td></td><td></td><td></td></tr><tr><td>AGGARWAL</td><td>RAAVI</td><td></td><td></td><td></td></tr><tr><td>AHMED</td><td>ANIQUE</td><td></td><td></td><td>X</td></tr><tr><td>ALBERS</td><td>THILO</td><td></td><td></td><td></td></tr><tr><td>ALFANI</td><td>GUIDO</td><td></td><td></td><td></td></tr><tr><td>ALVAREDO</td><td>FACUNDO</td><td>X</td><td>X</td><td></td></tr><tr><td>AMARANTE</td><td>VERONICA</td><td></td><td></td><td></td></tr><tr><td>ANDREESCU</td><td>MARIE</td><td>X</td><td></td><td>X</td></tr><tr><td>ARIAS OSORIO</td><td>MANUEL ESTEBAN</td><td></td><td></td><td>X</td></tr><tr><td>ARTOLA BLANCO</td><td>MIGUEL</td><td></td><td></td><td></td></tr><tr><td>ASSOUAD</td><td>LYDIA</td><td></td><td></td><td></td></tr><tr><td>ATRIA</td><td>JORGE</td><td></td><td></td><td></td></tr><tr><td>AZZOLLINI</td><td>LEO</td><td></td><td></td><td></td></tr><tr><td>BACHAS</td><td>PIERRE</td><td></td><td></td><td></td></tr><tr><td>BANERJEE</td><td>ABHIJIT</td><td></td><td></td><td></td></tr><tr><td>BANSAL</td><td>PRACHI</td><td></td><td></td><td>X</td></tr><tr><td>BANSAL</td><td>ROHAN</td><td></td><td></td><td></td></tr><tr><td>BARRERA</td><td>OSCAR</td><td></td><td></td><td></td></tr><tr><td>BARTELS</td><td>CHARLOTTE</td><td></td><td></td><td></td></tr><tr><td>BASELGIA</td><td>ENEA</td><td></td><td></td><td></td></tr><tr><td>BAULUZ</td><td>LUIZ</td><td>X</td><td></td><td></td></tr><tr><td>BAVARO</td><td>MICHEL</td><td></td><td></td><td></td></tr><tr><td>BENDARI</td><td>KHALED</td><td></td><td></td><td>X</td></tr><tr><td>BERGERON</td><td>AUGUSTIN</td><td></td><td></td><td></td></tr><tr><td>BERMAN</td><td>YONATAN</td><td></td><td></td><td></td></tr><tr><td>BEZY</td><td>THOMAS</td><td></td><td></td><td>X</td></tr><tr><td>BHARTI</td><td>NITIN KUMAR</td><td>X</td><td></td><td></td></tr><tr><td>BLANCHET</td><td>THOMAS</td><td></td><td></td><td></td></tr><tr><td>BONNEAU</td><td>CECILE</td><td></td><td></td><td></td></tr><tr><td>BONNET</td><td>FLORIAN</td><td></td><td></td><td></td></tr><tr><td>BORDERS</td><td>KANE</td><td></td><td></td><td>X</td></tr><tr><td>BOTHE</td><td>PHILIPP</td><td>X</td><td></td><td></td></tr><tr><td>BOURGUIGNON</td><td>FRANCOIS</td><td></td><td></td><td></td></tr></tbody></table>
<table><tr><td>BOZIO</td><td>ANTOINE</td><td></td><td></td><td></td></tr><tr><td>BRANDOLINI</td><td>ANDREA</td><td></td><td></td><td></td></tr><tr><td>BRASSAC</td><td>PIERRE</td><td></td><td></td><td>X</td></tr><tr><td>BREAU</td><td>SEBASTIEN</td><td></td><td></td><td></td></tr><tr><td>BRULHART</td><td>MARIUS</td><td></td><td></td><td></td></tr><tr><td>BUKOWSKI</td><td>PAWEL</td><td></td><td></td><td></td></tr><tr><td>BURDIN</td><td>GABRIEL</td><td></td><td></td><td></td></tr><tr><td>BURKHAUSER</td><td>RICHARD</td><td></td><td></td><td></td></tr><tr><td>BURQ</td><td>FRANCOIS</td><td></td><td></td><td>X</td></tr><tr><td>CAGE</td><td>JULIA</td><td></td><td></td><td></td></tr><tr><td>CAMPOS</td><td>RAYMUNDO</td><td></td><td></td><td></td></tr><tr><td>CARRANZA</td><td></td><td></td><td></td><td></td></tr><tr><td>NAVARRETE</td><td>RAFAEL</td><td></td><td></td><td></td></tr><tr><td>CASSAN</td><td>GUILHEM</td><td></td><td></td><td></td></tr><tr><td>CHANCEL</td><td>LUCAS</td><td>X</td><td>X</td><td></td></tr><tr><td>CHARALAMPIDIS</td><td>NIKOLAS</td><td></td><td></td><td></td></tr><tr><td>CHATTERJEE</td><td>AROOP</td><td></td><td></td><td></td></tr><tr><td>CHOU</td><td>TEYU</td><td></td><td></td><td></td></tr><tr><td>CHU</td><td>CYRUS</td><td></td><td></td><td></td></tr><tr><td>COGNEAU</td><td>DENIS</td><td></td><td></td><td></td></tr><tr><td>COWELL</td><td>FRANK</td><td></td><td></td><td></td></tr><tr><td>CRUCES</td><td>GUILLERMO</td><td></td><td></td><td></td></tr><tr><td>CZAJKA</td><td>LEO</td><td></td><td></td><td></td></tr><tr><td>D'AMBROSIO</td><td>CONCHITA</td><td></td><td></td><td></td></tr><tr><td>DE ROSE</td><td>MAURICIO</td><td></td><td></td><td></td></tr><tr><td>DE VICQ DE CUMPTICH</td><td>AMAURY</td><td></td><td></td><td></td></tr><tr><td>DEBUSSY</td><td>LAUREN</td><td>X</td><td></td><td>X</td></tr><tr><td>DECOSTER</td><td>ANDRE</td><td></td><td></td><td></td></tr><tr><td>DELL</td><td>FABIEN</td><td></td><td></td><td></td></tr><tr><td>DELORME</td><td>FRANCOIS</td><td></td><td></td><td></td></tr><tr><td>DIETRICH</td><td>JONAS</td><td></td><td></td><td>X</td></tr><tr><td>DISSILBACHER</td><td>FRANZISKA</td><td></td><td></td><td></td></tr><tr><td>DOUENNE</td><td>THOMAS</td><td></td><td></td><td></td></tr><tr><td>DRAY</td><td>SACHA</td><td></td><td></td><td></td></tr><tr><td>DRUSCHKE</td><td>PAULA</td><td></td><td></td><td>X</td></tr><tr><td>DURRER DE LA SOTA</td><td>CARMEN</td><td></td><td></td><td></td></tr><tr><td>EL HAIRI</td><td>DIMA</td><td>X</td><td></td><td>X</td></tr><tr><td>ESPONDA</td><td>FERNANDO</td><td></td><td></td><td></td></tr><tr><td>FABRE</td><td>ADRIEN</td><td></td><td></td><td></td></tr><tr><td>FAN</td><td>YI</td><td></td><td></td><td>X</td></tr><tr><td>FISHER-POST</td><td>MATTHEW</td><td>X</td><td></td><td></td></tr><tr><td>FLORES</td><td>IGNACIO</td><td>X</td><td></td><td></td></tr><tr><td>FOELLMI</td><td>RETO</td><td></td><td></td><td></td></tr><tr><td>FORSTER</td><td>MICHAEL</td><td></td><td></td><td></td></tr><tr><td>FORWARD</td><td>TAYLA</td><td></td><td></td><td>X</td></tr><tr><td>FOURNIER</td><td>JULIETTE</td><td></td><td></td><td></td></tr></table>
<table><tr><td>FRANK</td><td>MARK</td><td></td><td></td><td></td></tr><tr><td>FRANSHAM</td><td>MARK</td><td></td><td></td><td></td></tr><tr><td>GABRIELLI</td><td>VALENTINA</td><td>X</td><td></td><td>X</td></tr><tr><td>GARBINTI</td><td>BERTRAND</td><td></td><td></td><td></td></tr><tr><td>GARRIGA</td><td>SANTIAGO</td><td></td><td></td><td></td></tr><tr><td>GASPARINI</td><td>LEONARDO</td><td></td><td></td><td></td></tr><tr><td>GETHIN</td><td>AMORY</td><td>X</td><td></td><td></td></tr><tr><td>GODECHOT</td><td>OLIVIER</td><td></td><td></td><td></td></tr><tr><td>GOMEZ-CARRERA</td><td>RICARDO</td><td>X</td><td></td><td>X</td></tr><tr><td>GORNICK</td><td>JANET</td><td></td><td></td><td></td></tr><tr><td>GOUPILLE-LEBRET</td><td>JONATHAN</td><td></td><td></td><td></td></tr><tr><td>GOVIND</td><td>YAJNA</td><td></td><td></td><td></td></tr><tr><td>GROBON</td><td>SEBASTIEN</td><td></td><td></td><td></td></tr><tr><td>GUILLOT</td><td>MALKA</td><td></td><td></td><td></td></tr><tr><td>GUZZARDI</td><td>DEMETRICO</td><td></td><td></td><td></td></tr><tr><td>HERAULT</td><td>NICOLAS</td><td></td><td></td><td></td></tr><tr><td>HOLM</td><td>MARTIN B.</td><td></td><td></td><td></td></tr><tr><td>HONG</td><td>SEHYUN</td><td></td><td></td><td>X</td></tr><tr><td>IACONO</td><td>ROBERTO</td><td></td><td></td><td></td></tr><tr><td>JAKURTI</td><td>EDISON</td><td></td><td></td><td></td></tr><tr><td>JANTTI</td><td>MARKUS</td><td></td><td></td><td></td></tr><tr><td>JENDERNY</td><td>KATHARINA</td><td></td><td></td><td></td></tr><tr><td>JENKINS</td><td>STEPHEN</td><td></td><td></td><td></td></tr><tr><td>JENMANA</td><td>THANASAK</td><td></td><td></td><td></td></tr><tr><td>JENSEN</td><td>PETER SANDHOLST</td><td></td><td></td><td></td></tr><tr><td>JENSEN</td><td>ANDERS</td><td></td><td></td><td></td></tr><tr><td>KATIC</td><td>PAMELA</td><td></td><td></td><td></td></tr><tr><td>KENNICKELL</td><td>ARTHUR</td><td></td><td></td><td></td></tr><tr><td>KIM</td><td>JONGIL</td><td></td><td></td><td>X</td></tr><tr><td>KIM</td><td>NAK NYEON</td><td></td><td></td><td></td></tr><tr><td>KUMAR</td><td>RISHABH</td><td></td><td></td><td></td></tr><tr><td>LANDAIS</td><td>CAMILLE</td><td></td><td></td><td></td></tr><tr><td>LEE</td><td>NEIL</td><td></td><td></td><td></td></tr><tr><td>LEENDERS</td><td>WOUTER</td><td></td><td></td><td></td></tr><tr><td>LEIBBRANDT</td><td>MURRAY</td><td></td><td></td><td></td></tr><tr><td>LEIGH</td><td>ANDREW</td><td></td><td></td><td></td></tr><tr><td>LEITE</td><td>DAVID</td><td></td><td></td><td>X</td></tr><tr><td>LIN</td><td>MING-JEN</td><td></td><td></td><td></td></tr><tr><td>LONDONO VELEZ</td><td>JULIANA</td><td></td><td></td><td></td></tr><tr><td>LONSDALE</td><td>ANDREW</td><td></td><td></td><td></td></tr><tr><td>LOPEZ FERERO</td><td>MARGARITA</td><td></td><td></td><td></td></tr><tr><td>LOUBES</td><td>ROMAINE</td><td>X</td><td></td><td>X</td></tr><tr><td>LUGO</td><td>MARIA ANA</td><td></td><td></td><td></td></tr><tr><td>LUNDBERG</td><td>JACOB</td><td></td><td></td><td></td></tr><tr><td>LUSTIG</td><td>NORA</td><td></td><td></td><td></td></tr><tr><td>MARTINEZ</td><td>ISABEL</td><td></td><td></td><td></td></tr></table>
<table><tr><td>MARTINEZ TOLEDANO</td><td>CLARA</td><td>X</td><td></td><td></td></tr><tr><td>MATTAUCH</td><td>LINUS</td><td></td><td></td><td></td></tr><tr><td>MAURIZIO</td><td>ROXANA</td><td></td><td></td><td></td></tr><tr><td>MAYER</td><td>RICARDO</td><td></td><td></td><td></td></tr><tr><td>MILANOVIC</td><td>BRANKO</td><td></td><td></td><td></td></tr><tr><td>MIRANTI</td><td>RIYANA</td><td></td><td></td><td></td></tr><tr><td>MO</td><td>ZHEXUN</td><td>X</td><td></td><td></td></tr><tr><td>MOATSOS</td><td>MICHAIL</td><td></td><td></td><td></td></tr><tr><td>MODALSLI</td><td>JORGEN</td><td></td><td></td><td></td></tr><tr><td>MOHREN</td><td>CORNELIA</td><td>X</td><td></td><td></td></tr><tr><td>MORELLI</td><td>SALVATORE</td><td></td><td></td><td></td></tr><tr><td>MORGAN</td><td>MARC</td><td></td><td></td><td></td></tr><tr><td>MORIGUCHI</td><td>CHIAKI</td><td></td><td></td><td></td></tr><tr><td>MOSHRIF</td><td>ROWAIDA</td><td>X</td><td></td><td>X</td></tr><tr><td>MUNOZ</td><td>MATHILDE</td><td></td><td></td><td></td></tr><tr><td>MURPHY</td><td>BRIAN</td><td></td><td></td><td></td></tr><tr><td>MUTI</td><td>STELLA</td><td></td><td></td><td>X</td></tr><tr><td>NEEF</td><td>THERESA</td><td></td><td></td><td></td></tr><tr><td>NIEVAS OFFIDANI</td><td>GASTON</td><td>X</td><td></td><td></td></tr><tr><td>NOLAN</td><td>BRIAN</td><td></td><td></td><td></td></tr><tr><td>NOVOKMET</td><td>FILIP</td><td></td><td></td><td></td></tr><tr><td>NYBORG STOSTAD</td><td>MORTEN</td><td></td><td></td><td></td></tr><tr><td>ODERSKY</td><td>MORITZ</td><td></td><td></td><td></td></tr><tr><td>OHLSSON</td><td>HENRY</td><td></td><td></td><td></td></tr><tr><td>OLIVEIRA</td><td>CARLOS</td><td></td><td></td><td></td></tr><tr><td>OOMS</td><td>TAHNEE</td><td></td><td></td><td></td></tr><tr><td>ORTHOFER</td><td>ANNA</td><td></td><td></td><td></td></tr><tr><td>PALAGI</td><td>ELISA</td><td></td><td></td><td></td></tr><tr><td>PIKETTY</td><td>THOMAS</td><td>X</td><td>X</td><td></td></tr><tr><td>PINTO</td><td>FLORA</td><td></td><td></td><td></td></tr><tr><td>PISANO</td><td>ELENA</td><td></td><td></td><td></td></tr><tr><td>PRICE</td><td>MARK</td><td></td><td></td><td>X</td></tr><tr><td>QIAN</td><td>NANCY</td><td></td><td></td><td></td></tr><tr><td>QIAN</td><td>WENLAN</td><td></td><td></td><td></td></tr><tr><td>RASTER</td><td>TOM</td><td></td><td></td><td>X</td></tr><tr><td>REHM</td><td>YANNIC</td><td></td><td></td><td></td></tr><tr><td>RIIHELA</td><td>MARJA</td><td></td><td></td><td></td></tr><tr><td>ROBILLIARD</td><td>ANNE SOPHIE</td><td>X</td><td></td><td></td></tr><tr><td>ROINE</td><td>JESPER</td><td></td><td></td><td></td></tr><tr><td>ROVENTINI</td><td>ANDREA</td><td></td><td></td><td></td></tr><tr><td>ROY</td><td>SUTANUKA</td><td></td><td></td><td></td></tr><tr><td>SAEZ</td><td>EMMANUEL</td><td>X</td><td>X</td><td></td></tr><tr><td>SAINT JACQUES</td><td>GUILLAUME</td><td></td><td></td><td></td></tr><tr><td>SALVERDA</td><td>WIEMER</td><td></td><td></td><td></td></tr><tr><td>SANCHEZ ORDONEZ</td><td>DANIEL</td><td></td><td></td><td></td></tr><tr><td>SANDEFUR</td><td>JUSTIN</td><td></td><td></td><td></td></tr></table>
<table><tr><td>SANHUEZA</td><td>CLAUDIA</td><td></td><td></td><td></td></tr><tr><td>SCHINKE</td><td>CHRISTOPH</td><td></td><td></td><td></td></tr><tr><td>SCHULARICK</td><td>MORITZ</td><td></td><td></td><td></td></tr><tr><td>SEGAL</td><td>PAUL</td><td></td><td></td><td></td></tr><tr><td>SEMIENIUK</td><td>GREGOR</td><td></td><td></td><td></td></tr><tr><td>SHARP</td><td>PAUL</td><td></td><td></td><td></td></tr><tr><td>SING</td><td>TIEN FOO</td><td></td><td></td><td></td></tr><tr><td>SINGH</td><td>RAM</td><td></td><td></td><td></td></tr><tr><td>SIRUGUE</td><td>LOUIS</td><td></td><td></td><td></td></tr><tr><td>SMEEDING</td><td>TIMOTHY</td><td></td><td></td><td></td></tr><tr><td>SODANO</td><td>ALICE</td><td>X</td><td></td><td></td></tr><tr><td>SOGAARD</td><td>JAKOB EGHOLT</td><td></td><td></td><td></td></tr><tr><td>SOMANCHI</td><td>ANMOL</td><td>X</td><td></td><td></td></tr><tr><td>SOMMEILLER</td><td>ESTELLE</td><td></td><td></td><td></td></tr><tr><td>SORIA</td><td>JAVIER</td><td></td><td></td><td></td></tr><tr><td>SOTURA</td><td>AURELIE</td><td></td><td></td><td></td></tr><tr><td>STANTCHEVA</td><td>STEFANIE</td><td></td><td></td><td></td></tr><tr><td>SU</td><td>HSUAN-LI</td><td></td><td></td><td></td></tr><tr><td>SUBRAMANIAN</td><td>S</td><td></td><td></td><td></td></tr><tr><td>SULLSTROM</td><td>RITO</td><td></td><td></td><td></td></tr><tr><td>SUMMERS</td><td>ANDY</td><td></td><td></td><td></td></tr><tr><td>TARGA</td><td>MATTEO</td><td></td><td></td><td></td></tr><tr><td>TARRANT</td><td>HANNAH</td><td></td><td></td><td></td></tr><tr><td>TOUSSAINT</td><td>SIMON</td><td></td><td></td><td></td></tr><tr><td>TSOUKALIS</td><td>PANOS</td><td></td><td></td><td></td></tr><tr><td>TUOMALA</td><td>MATTI</td><td></td><td></td><td></td></tr><tr><td>URAZ</td><td>JULIET-NIL</td><td></td><td></td><td></td></tr><tr><td>VAN DER ENG</td><td>PIERRE</td><td></td><td></td><td></td></tr><tr><td>VEALL</td><td>MICHAEL</td><td></td><td></td><td></td></tr><tr><td>VERDURO</td><td>GREGORY</td><td></td><td></td><td></td></tr><tr><td>VIGORITO</td><td>ANDREA</td><td></td><td></td><td></td></tr><tr><td>VOITURIEZ</td><td>TANCREDE</td><td></td><td></td><td></td></tr><tr><td>WALDENSTROM</td><td>DANIEL</td><td></td><td></td><td></td></tr><tr><td>WANG</td><td>QING</td><td></td><td></td><td>X</td></tr><tr><td>WILKINS</td><td>ROGER</td><td></td><td></td><td></td></tr><tr><td>WOOLARD</td><td>INGRID</td><td></td><td></td><td></td></tr><tr><td>WOO-MORA</td><td>GUILLERMO</td><td></td><td></td><td></td></tr><tr><td>WRONSKI</td><td>MARCIN</td><td></td><td></td><td></td></tr><tr><td>XUEREB</td><td>SILAS</td><td></td><td></td><td></td></tr><tr><td>YANG</td><td>LINUS</td><td></td><td></td><td></td></tr><tr><td>YUSUF</td><td>ARIEF ANSHORY</td><td></td><td></td><td></td></tr><tr><td>ZUCMAN</td><td>GABRIEL</td><td>X</td><td>X</td><td></td></tr><tr><td>ZUNIGA-CORDERO</td><td>ALVARO</td><td>X</td><td></td><td></td></tr><tr><td>ZTYNSKI</td><td>STANISLAW</td><td></td><td></td><td>X</td></tr></table>
Note: 'IC' stands for Inner Circle, 'WIL' stands for World Inequality Lab. The 'Missing' column indicates authors which we were not able to identify in OpenAlex database by the time of the API requests.
<table><caption>Table A.2: Top 20 Cited Authors</caption><thead><tr><td>Rank</td><td>EMMANUEL SAEZ</td><td>FACUNDO ALVAREDO</td><td>GABRIEL ZUCMAN</td><td>LUCAS CHANCEL</td><td>THOMAS PIKETTY</td></tr></thead><tbody><tr><td>1</td><td>emmanuel saez</td><td>anthony b atkinson</td><td>gabriel zucman</td><td>thomas piketty</td><td>thomas piketty</td></tr><tr><td>2</td><td>thomas piketty</td><td>thomas piketty</td><td>thomas piketty</td><td>gabriel zucman</td><td>anthony b atkinson</td></tr><tr><td>3</td><td>peter diamond</td><td>emmanuel saez</td><td>emmanuel saez</td><td>emmanuel saez</td><td>emmanuel saez</td></tr><tr><td>4</td><td>anthony b atkinson</td><td>facundo alvaredo</td><td>niels johannesen</td><td>facundo alvaredo</td><td>gabriel zucman</td></tr><tr><td>5</td><td>gabriel zucman</td><td>martin ravallion</td><td>anthony b atkinson</td><td>anthony b atkinson</td><td>simon kuznets</td></tr><tr><td>6</td><td>raj chetty</td><td>simon kuznets</td><td>joel slemrod</td><td>lucas chancel</td><td>wojciech kopczuk</td></tr><tr><td>7</td><td>joel slemrod</td><td>wojciech kopczuk</td><td>wojciech kopczuk</td><td>branko milanovi</td><td>jonathan goupillelebret</td></tr><tr><td>8</td><td>pascal michaillat</td><td>gabriel zucman</td><td>henrik kleven</td><td>gregor semieniuk</td><td>joseph e stiglitz</td></tr><tr><td>9</td><td>james m poterba</td><td>a harrison</td><td>annette alstadster</td><td>jeanfranois mercure</td><td>jeanlaurent rosenthal</td></tr><tr><td>10</td><td>martin feldstein</td><td>andrew leigh</td><td>kimberly a clausing</td><td>marshall burke</td><td>gilles postelvinay</td></tr><tr><td>11</td><td>wojciech kopczuk</td><td>branko milanovi</td><td>claus thustrup kreiner</td><td>thomas blanchet</td><td>facundo alvaredo</td></tr><tr><td>12</td><td>james a mirrlees</td><td>frank cowell</td><td>daniel waldenstrm</td><td>denis cogneau</td><td>bertrand garbinti</td></tr><tr><td>13</td><td>lawrence f katz</td><td>vito tanzi</td><td>philip r lane</td><td>neil r edwards</td><td>stefanie stantcheva</td></tr><tr><td>14</td><td>robert e hall</td><td>francisco h g ferreira</td><td>edward n wolff</td><td>philippe aghion</td><td>abhijit banerjee</td></tr><tr><td>15</td><td>simon kuznets</td><td>angus deaton</td><td>james r hines</td><td>joseph e stiglitz</td><td>a harrison</td></tr><tr><td>16</td><td>alan j auerbach</td><td>james m poterba</td><td>peter h lindert</td><td>stefanie stantcheva</td><td>stephen p jenkins</td></tr><tr><td>17</td><td>henrik kleven</td><td>franos bourguignon</td><td>stefanie stantcheva</td><td>manfred lenzen</td><td>peter h lindert</td></tr><tr><td>18</td><td>christopher a pissarides</td><td>daron acemolu</td><td>simon kuznets</td><td>stphane hallegatte</td><td>james m poterba</td></tr><tr><td>19</td><td>joseph e stiglitz</td><td>jeffrey g williamson</td><td>jesper roine</td><td>mette wier</td><td>joel slemrod</td></tr><tr><td>20</td><td>david card</td><td>nora lustig</td><td>nadine riedel</td><td>julie rozenberg</td><td>franos bourguignon</td></tr></tbody></table>
<table><caption>Table A.3: Inner Circle, WIL and WID Fellows - Co-Authorship Relations</caption><thead><tr><th>Author/Co-author</th><th>E. S.</th><th>F. A.</th><th>G. Z.</th><th>L. C.</th><th>T. P.</th><th>IC</th><th>WIL</th><th>WID Fellows</th><th>Only one</th><th>N</th></tr></thead><tbody><tr><td>E. S.</td><td>-</td><td>38(40%)</td><td>54(57%)</td><td>37(39%)</td><td>42(45%)</td><td>57(61%)</td><td>0(0%)</td><td>7(7%)</td><td>31(33%)</td><td>94</td></tr><tr><td>F. A.</td><td>38(68%)</td><td>-</td><td>37(66%)</td><td>40(71%)</td><td>45(80%)</td><td>46(82%)</td><td>0(0%)</td><td>12(21%)</td><td>2(4%)</td><td>56</td></tr><tr><td>G. Z.</td><td>54(61%)</td><td>37(42%)</td><td>-</td><td>37(42%)</td><td>48(54%)</td><td>62(70%)</td><td>2(2%)</td><td>9(10%)</td><td>23(26%)</td><td>89</td></tr><tr><td>L. C.</td><td>37(61%)</td><td>40(66%)</td><td>37(61%)</td><td>-</td><td>46(75%)</td><td>46(75%)</td><td>4(7%)</td><td>10(16%)</td><td>5(8%)</td><td>61</td></tr><tr><td>T. P.</td><td>42(29%)</td><td>45(31%)</td><td>48(33%)</td><td>46(32%)</td><td>-</td><td>62(43%)</td><td>19(13%)</td><td>36(25%)</td><td>46(32%)</td><td>145</td></tr><tr><td>IC</td><td>57(23%)</td><td>46(18%)</td><td>62(25%)</td><td>46(18%)</td><td>62(25%)</td><td>77(31%)</td><td>25(10%)</td><td>64(26%)</td><td>107(43%)</td><td>249</td></tr><tr><td>WIL</td><td>0(0%)</td><td>0(0%)</td><td>2(2%)</td><td>4(4%)</td><td>19(18%)</td><td>25(24%)</td><td>19(18%)</td><td>52(50%)</td><td>37(36%)</td><td>103</td></tr><tr><td>WID Fellows</td><td>7(0%)</td><td>12(0%)</td><td>9(0%)</td><td>10(0%)</td><td>36(1%)</td><td>64(2%)</td><td>52(1%)</td><td>340(8%)</td><td>3816(90%)</td><td>4223</td></tr></tbody></table>

Note: The table presents co-authorship relations among (groups of) authors based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. E.S.: Emmanuel Saez; F.A.: Facundo Alvaredo; G.Z.: Gabriel Zucman; L.C.: Lucas Chancel; T.P.: Thomas Piketty. IC stands for 'Inner Circle', composed of Thomas Piketty, Emmanuel Saez, Gabriel Zucman, Facundo Alvaredo and Lucas Chancel. WIL stands for 'World Inequality Lab', and is reduced here to all members of the actual WIL as of 28/08/2025 except members of the IC (that is 14 members). WID Fellows regroups all scholars listed as fellows of the World Inequality Database (WID) as of 28/08/2025 except members of the IC or of the WIL (that is 172 scholars). Notably, our data collection process does not identify works from 9 WIL members and 36 WID Fellows, which are thus excluded from our analysis. The 'N' column indicates the total number of documents a given author wrote with at least one co-author. For groups of authors, this column indicates the number of documents that contain several authors with at least one member of this group. The 'Only one' column indicates the number (and percentage) of documents written by one member of a group of authors that also does not contain any (other) member from the groups (either IC, WIL or WID Fellows). Cells in all other columns contain the count and percentage of co-authored documents between two (groups of) authors. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of co-authored documents (#Docs column). Rows IC, WIL and WID Fellows count the number (and percentage) of documents that have been written by at least one member of each group and by the author listed in the corresponding column (if single author) or by at least one member of the group listed in the corresponding column (if group). For instance, T. Piketty co-authored 145 documents in our dataset, among which 42 were co-authored with E. Saez and 19 were co-authored with at least one member of the WIL (hence 29% and 13% of all documents co-authored by Piketty, respectively). Similarly, members of the WIL co-authored 19 documents with at least one other member of the WIL (18% of the total number of documents written by at least one member of the WIL and at least one other author). Furthermore, members of the WIL wrote 37 documents that have not also been written by any other member from the groups (IC, WIL and WID Fellows), which corresponds to 36% of the total number of documents written by at least one member of the WIL.
<table><caption>Table A.4: Inner Circle, WIL and WID Fellows - Citation Relations</caption><thead><tr><th>Author/Cited</th><th></th><th>E. S.</th><th>F. A.</th><th>G. Z.</th><th>L. C.</th><th>T. P.</th><th>IC</th><th>WIL</th><th>WID Fellows</th><th>N<sup>c</sup></th><th>N<sup>d</sup></th></tr></thead><tbody><tr><td rowspan="2">E. S.</td><td>cites</td><td>75(2%)</td><td>1(0%)</td><td>56(1%)</td><td>1(0%)</td><td>22(0%)</td><td>108(2%)</td><td>2(0%)</td><td>46(1%)</td><td rowspan="2">4856</td><td rowspan="2">50</td></tr><tr><td>docs with cites</td><td>39(78%)</td><td>2(4%)</td><td>22(44%)</td><td>1(2%)</td><td>23(46%)</td><td>42(84%)</td><td>3(6%)</td><td>29(58%)</td></tr><tr><td rowspan="2">F. A.</td><td>cites</td><td>3(0%)</td><td>7(1%)</td><td>9(1%)</td><td>0(0%)</td><td>9(1%)</td><td>22(2%)</td><td>1(0%)</td><td>32(3%)</td><td rowspan="2">1135</td><td rowspan="2">16</td></tr><tr><td>docs with cites</td><td>11(69%)</td><td>8(50%)</td><td>5(31%)</td><td>0(0%)</td><td>12(75%)</td><td>14(88%)</td><td>1(6%)</td><td>12(75%)</td></tr><tr><td rowspan="2">G. Z.</td><td>cites</td><td>57(4%)</td><td>8(0%)</td><td>109(7%)</td><td>3(0%)</td><td>49(3%)</td><td>145(9%)</td><td>4(0%)</td><td>63(4%)</td><td rowspan="2">1622</td><td rowspan="2">42</td></tr><tr><td>docs with cites</td><td>32(76%)</td><td>5(12%)</td><td>36(86%)</td><td>3(7%)</td><td>28(67%)</td><td>39(93%)</td><td>4(10%)</td><td>25(60%)</td></tr><tr><td rowspan="2">L. C.</td><td>cites</td><td>12(2%)</td><td>14(2%)</td><td>25(3%)</td><td>12(2%)</td><td>21(3%)</td><td>52(7%)</td><td>8(1%)</td><td>67(9%)</td><td rowspan="2">768</td><td rowspan="2">20</td></tr><tr><td>docs with cites</td><td>12(60%)</td><td>7(35%)</td><td>10(50%)</td><td>8(40%)</td><td>13(65%)</td><td>16(80%)</td><td>6(30%)</td><td>16(80%)</td></tr><tr><td rowspan="2">T. P.</td><td>cites</td><td>35(1%)</td><td>17(1%)</td><td>61(2%)</td><td>6(0%)</td><td>77(2%)</td><td>124(4%)</td><td>13(0%)</td><td>103(3%)</td><td rowspan="2">3096</td><td rowspan="2">60</td></tr><tr><td>docs with cites</td><td>28(47%)</td><td>12(20%)</td><td>26(43%)</td><td>4(7%)</td><td>43(72%)</td><td>43(72%)</td><td>10(17%)</td><td>35(58%)</td></tr><tr><td rowspan="2">IC</td><td>cites</td><td>127(1%)</td><td>36(0%)</td><td>170(2%)</td><td>19(0%)</td><td>124(1%)</td><td>316(3%)</td><td>25(0%)</td><td>259(3%)</td><td rowspan="2">9258</td><td rowspan="2">136</td></tr><tr><td>docs with cites</td><td>87(64%)</td><td>23(17%)</td><td>63(46%)</td><td>13(10%)</td><td>72(53%)</td><td>75(55%)</td><td>17(12%)</td><td>87(64%)</td></tr><tr><td rowspan="2">WIL</td><td>cites</td><td>80(3%)</td><td>24(1%)</td><td>75(2%)</td><td>11(0%)</td><td>134(4%)</td><td>211(7%)</td><td>65(2%)</td><td>221(7%)</td><td rowspan="2">3017</td><td rowspan="2">129</td></tr><tr><td>docs with cites</td><td>28(22%)</td><td>10(8%)</td><td>22(17%)</td><td>8(6%)</td><td>39(30%)</td><td>40(31%)</td><td>14(11%)</td><td>55(43%)</td></tr><tr><td rowspan="2">WID Fellows</td><td>cites</td><td>1176(1%)</td><td>280(0%)</td><td>606(0%)</td><td>66(0%)</td><td>1472(1%)</td><td>2531(2%)</td><td>156(0%)</td><td>5407(4%)</td><td rowspan="2">133030</td><td rowspan="2">6415</td></tr><tr><td>docs with cites</td><td>741(12%)</td><td>228(4%)</td><td>285(4%)</td><td>49(1%)</td><td>682(11%)</td><td>963(15%)</td><td>203(3%)</td><td>2188(34%)</td></tr></tbody></table>

Note: The table presents citation relations among (groups of) authors based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. E.S.: Emmanuel Saez; F.A.: Facundo Alvaredo; G.Z.: Gabriel Zucman; L.C.: Lucas Chancel; T.P: Thomas Piketty. WIL stands for 'World Inequality Lab', and is reduced here to all members of the actual WIL as of 28/08/2025 except members of the IC (that is 14 members). WID Fellows regroups all scholars listed as fellows of the World Inequality Database (WID) as of 28/08/2025 except members of the IC or of the WIL (that is 172 scholars). Notably, our data collection process does not identify works from 9 WIL members and 36 WID Fellows, which are thus excluded from our analysis. For WIL and WID Fellows, we further restrict the dataset to documents published after 2015, that is the creation date of the WIL/WID. More specifically, for all (groups of) authors, we scrutinize the referenced works from all documents published after this date. Then, when members of the WIL or WID Fellows are cited, we consider only cited documents after this date. For members of the Inner Circle it depends on who cites them: if it is another member of the Inner Circle we consider only cited documents after this date (the table
specific to this group provides the remaining piece of information); if it is a member of another group we consider the full period. The N<sup>C</sup> column indicates the total number of documents a given author or cites. For groups of authors, this column indicates the number of documents that are cited by authors from this group. The N<sup>D</sup> column indicates the total number of documents for which the database contains at least one referenced work. Cells in all other columns contain the count and percentage of documents written by the column author/group and cited by the row author/group. Rows labeled 'cites' indicate citation relations between two authors/groups. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of cited documents (N<sup>C</sup> column). Rows labeled 'docs with cite' indicate the number of documents written by the row author that cite the author. Percentages (in parentheses, rounded to the nearest unit) are computed with respect to the number of documents that contain at least one reference in the database (N<sup>D</sup> column). For instance, starting 2015, T. Piketty wrote 60 documents which contain at least one referenced work. These documents cite 3096 documents, among which 35 were written by E. Saez (hence 1% of all documents cited by Piketty). Also, Piketty cites Saez in 28 documents, that is in 47% of Piketty's documents in which there is at least one reference. Similarly, members of the WIL wrote 129 which contain at least one referenced work. These documents cite 65 documents with at least one other member of the WIL (2% of the total number of documents cited by at least one member of the WIL. Also, members of the WIL cite other members of the WIL in 14 documents, that is in 11% of documents written by at least one member of the WIL and in which there is at least one reference.
<figure><img src="image_3.png" /><figcaption>Figure A.1:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one member of the Inner Circle (IC) based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_4.png" /><figcaption>Figure A.2:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by Thomas Piketty based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics corresponds to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_5.png" /><figcaption>Figure A.3:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by Emmanuel Saez based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics corresponds to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_6.png" /><figcaption>Figure A.4:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by Gabriel Zucman based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics corresponds to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_7.png" /><figcaption>Figure A.5:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by Facundo Alvaredo based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics correspond to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_8.png" /><figcaption>Figure A.6:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by Lucas Chancel based on a bibliometric search restricted on articles, books, book chapters and reports using OpenAlex API. The list of topics corresponds to the 20 most frequent topics for this author. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_9.png" /><figcaption>Figure A.7:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least two members of the WIL based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider all official members of the WIL (thus including members of the Inner Circle). The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_10.png" /><figcaption>Figure A.8:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one member of the WIL based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider all official members of the WIL (thus including members of the Inner Circle). The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_11.png" /><figcaption>Figure A.9:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one member of the WIL based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider only members of the WIL that are not also members of the Inner Circle. The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_12.png" /><figcaption>Figure A.10:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least two WID Fellows based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider all official WID Fellows (thus including members of the Inner Circle and members of the WIL). The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_13.png" /><figcaption>Figure A.11:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one WID Fellow based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider all official WID Fellows (thus including members of the Inner Circle and members of the WIL). The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_14.png" /><figcaption>Figure A.12:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one WID Fellow based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider WID Fellows that are not also members of the Inner Circle. The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.
<figure><img src="image_15.png" /><figcaption>Figure A.13:</figcaption></figure>

Note: This Figure plots the number of times the listed topics are associated with documents written by at least one WID Fellow based on a bibliometric search restricted on articles, books, book chapters and reports published after 2015 using OpenAlex API. Here, we consider WID Fellows that are not also members of the WIL (and by extension members of the Inner Circle). The list of topics corresponds to the 20 most frequent topics for this group. A machine learning prediction algorithm is used by the database's team to assign topics to documents. S is the average score that the prediction model assigns to a topic over all documents associated with this topic.