Some clarifications on economic negationism

By Pierre Cahuc and André Zylberberg

We would like to thank Xavier Ragot for permitting us to respond to his comments about our book, Le Négationnisme économique [Economic Negationism]. Like many critics, Xavier Ragot considered that:

1) “The very title of the book proceeds from great violence. This book is on a slippery slope in the intellectual debate that is heading towards a caricature of debate and verbal abuse.”

2) The approach of our work is “scientistic” and “reductive”, with “faith in knowledge drawn from natural experiments” that he doesn’t believe has a “consensus in economics”.

3) We “want to import the hierarchy of academic debate into the public debate”.

We would like to respond to these three allegations, with which we disagree. 

1) On economic negationism

The term “economic negationism” does not caricature the debate. We chose it because the notion of “scientific negationism” is an expression used in debates about science, and we are talking about science here. This term is in common use, for instance on the scientific blog of the newspaper Le Monde, “Passeurs de Sciences”, which was named the best blog in the field of science. Our work reviews the significance of the term in the introduction, and then further develops this in Chapter 7. We note that scientific negationism is a strategy based on four pillars:

  • Throw doubt on and castigate “la pensée unique” [doctrinaire, dogmatic “group think”];
  • Denounce moneyed and ideological interests;
  • Condemn science because it can’t explain everything;
  • Promote “alternative” learned societies.

This strategy aims to discredit researchers who are getting what are considered disturbing results. It affects all disciplines to one extent or another, as is shown by the works of Robert Proctor[1] and Naomi Oreské and Erik Conway[2]. And this is precisely the strategy adopted both by the Economistes Atterrés[3] and in the book entitled A quoi servent les économistes s’ils disent tous la même chose [What good are economists if they all say the same thing][4]. These texts all rely on the four pillars of scientific negationism set out above. They loudly proclaim the existence of dogmatic “group think” (pillar 1), which more or less accedes to the demands of the financial markets (pillar 2), and is thus unable to foresee financial crises (Pillar 3), resulting in the need to create alternative learned societies (and while the AFEP, the French association of political economists, already exists, there are demands to open a new economics section in the University) (pillar 4).

This strategy does not nourish debate. It annihilates it. It is intended solely to discredit researchers, both recognized and anonymous. Jean Tirole was recently the victim of this kind of discrediting by some self-proclaimed “heterodox” economists.

2) With regard to a scientistic and reductive approach

Xavier Ragot says that “giving a consensus among economists the status of truth” (Cahuc, Zylberberg, p. 185) is troublesome, because it ignores the contributions of “minority” efforts. We are not erecting some consensus about truth; rather, we say very specifically (p. 185) that a consensus, when it exists, is the best approximation of the “truth”. The use of quotation marks around the word truth and the qualification best approximation show clearly that we are not advocating some notion of scientistic absolutism. Our use of the terms consensus and truth seems to us to correspond to the usual practice in the scientific process.

To bolster our position on this point, we’d like to cite our book once more, on pages 184-185: “Trusting in a community made up of thousands of researchers remains the best option for having an informed opinion about subjects that we don’t really understand. It is nevertheless a form of betting, because even if science is the most reliable way to produce knowledge, it may be wrong. But to systematically call into question the results obtained by scientific specialists on a given question and prefer to rely on self-proclaimed experts is far riskier”; and on page 186: “The development of knowledge involves a collective undertaking where every researcher produces results that other researchers then test for their robustness. ‘Scientific knowledge’ is the photograph of this collective endeavour at a given point. This is the most reliable picture of what we know about the state of the world. This image is not fixed, but is in fact constantly changing.”

So when no empirical study on the reduction of statutory or contractual working hours (excluding the reduction of charges) finds a positive effect on employment, there are no grounds for asserting that reducing working time can create jobs … so long as no published studies find the opposite. Economic negationism leads to denying these results, saying that they stem from dogmatic thinking guided by either ignorance of the real world or a conspiracy. We affirm therefore that further debate is necessary, but to be constructive it must follow certain rules: the arguments must be based on contributions that have passed “peer review” to be certified as relevant. Of course, on many topics the existing studies do not make it possible to identify convergent results. When this is the case, it has to be acknowledged. There are several illustrations of this in our book.

3) On our recommendations for opening up debate and making it transparent

As we have mentioned before, our objective is not to close the “intellectual debate” to public access by laypeople, but to make the debate more constructive and informative. Debates on economics, even when simply presenting the facts, are often treated as political confrontations or boxing matches between different schools of thought. We’re simply saying that to organize informative discussion (page 209), “Journalists should stop systematically calling on the same people, especially when they have no proven research activity but are nevertheless capable of expressing themselves on every subject. They should instead seek out genuine specialists. The ranking of more than 800 economists in France on the IDEAS website can help them select relevant speakers. In any case, the web pages of researchers should be consulted to ensure that their publications appear in reputable scientific journals, a list of which is available on the same IDEAS site. If an economist hasn’t published anything in the last five years in one of the 1,700 journals listed on this site, it is clear that this person has not been an active researcher for a long time, and it is best to talk to someone one else to get an informed opinion. Journalists should also systematically ask for references to the articles researchers rely on for their judgments and, where applicable, request that these items be made available online to readers, listeners and viewers.”

So, far from wanting to “import the hierarchy of the academic debate into the public debate”, as Xavier Ragot puts it, we simply want for non-specialists to be better informed about the academic debate, so that they are able to distinguish what are matters of uncertainty (or consensus) among researchers with regard to the political options being presented.


[1] Golden Holocaust: La Conspiration des industriels du tabac, Sainte Marguerite sur Mer, Équateurs, 2014.

[2] Les Marchands de doute. Ou comment une poignée de scientifiques ont masqué la vérité sur des enjeux de société́ tels que le tabagisme et le réchauffement climatique, Paris, Editions le Pommier, 2012.

[3] Manifeste des économistes atterrés (2010) and Nouveau manifeste des économistes atterrés (2015), éditions LLL.

[4] Editions LLL 2015.


“The economic negationism” of Cahuc and Zylberberg: the first-order economy

By Xavier Ragot

The book by Pierre Cahuc and André Zylberberg[1] is an injunction to take scientific truths about economics into account in the public debate, in the face of interventions that conceal private and ideological interests. The book contains interesting descriptions of the results of recent empirical work using natural experiments for the purpose of evaluating economic policies in the field of education, tax policy, the reduction of working hours, etc.

However, assertions in the book that are at the borderline of reason ultimately make it a caricature that is probably counter-productive. More than just the debate over the 35-hour working week or France’s CICE tax credit, what is at stake is the status of economic knowledge in the public debate.

1) Has economics become an experimental science like medicine and biology?

The heart of the book is the claim that economic science produces knowledge to treat social ills that is on the same scientific level as medicine. I do not believe this is true. Consider this quote from the winner of the 2015 Nobel Prize in Economics, Angus Deaton:

“I argue that experiments have no special ability to produce more credible knowledge than other methods, and that actual experiments are frequently subject to practical problems that undermine any claims to statistical or epistemic superiority.” (Deaton 2010)

The charge is serious; the point is not to deny the contributions of economic experiments but to understand their limitations and to recognize that there are many other approaches in economics (natural or controlled experiments constitute only a small percentage of the empirical work in economics).

What are the limits of experiments? Natural experiments serve only to measure average first-order effects without measuring secondary effects (so-called general equilibrium effects) that can significantly change the results. A well-known example: the work of the Nobel laureate Heckman (1998) in the economics of education, which showed that, at least in some cases, these general equilibrium effects significantly affect the results of experiments.

Moreover, experiments are not able to take into account the heterogeneity of the effects on populations, to accurately measure the confidence intervals, etc. I’ll leave these technical discussions to the article by Deaton. It should also be noted that the power to generalize from natural experiments is often weak, as these experiments are by their nature not reproducible.

Let’s take an example: Cahuc and Zylberberg use the study by Mathieu Chemin and Etienne Wasmer (2009) comparing the effects of the reduction of working time between Alsace and the whole of France to identify the impact on employment of an additional reduction of 20 minutes of working time. This work finds no impact from an additional 20-minute reduction in working time on employment. Can we conclude that the transition to 35 hours, a reduction in working time more than ten times as great, has no impact on employment? Could there be interaction effects between lowering social contributions and reducing working time? I don’t think it can be said that simply reducing working time creates jobs, but it seems difficult to claim scientifically that the transition to 35 hours did not create jobs based on the studies cited (the authors also draw on the example of Quebec, where the reduction was much greater).

The economist uses data in much more diverse ways than presented by Cahuc and Zylberberg. The book does not discuss laboratory experiments conducted in economics (see Levitt and List, 2007). Further, the relationship of economics to data is undergoing change as digital distribution creates vast access to data (“big data” in short). Econometric techniques will in all likelihood make more intense use of structural econometrics. In a recent work (Challe et al., 2016), we develop, for example, a framework for using both microeconomic and macroeconomic data to measure the impact of the great recession in the US. Finally, there has been a renewal of economic history and long-series studies. The work of Thomas Piketty is an example that has not gone unnoticed. Other work, including on financial instability (especially that by Moritz Schularik and Alan M. Taylor), also uses long time periods to enhance intelligibility. In short, the relationship of data to economics involves multiple methods that can yield conflicting results.

This is no mere detail: the scientistic approach of the book is reductive. The book by Zylberberg Cahuc advances a faith in the knowledge drawn from natural experiments that I don’t believe has a consensus in economics.

2) How to sidestep major questions

Here is a concrete illustration of the problem with this approach. The authors render a severe verdict on France’s CICE tax credit (the government’s reduction of employer social charges on up to 2.5 times the minimum wage, the SMIC). The main argument is that it is well known that reducing charges in the neighbourhood of the SMIC has a much bigger impact on employment than for higher wage levels. This last point is true – but the authors are sidestepping the real issue. What is it?

The early years of the euro have seen an unprecedented divergence in labour costs and inflation between European countries. Up to the 1990s, these differences were handled over the years by devaluations / revaluations. But the single currency has made this no longer possible. The question facing economists looking at this situation is whether the euro zone can survive such misalignments (see the recent position of Stiglitz on this subject). The discussion has been focused on establishing internal devaluations in overvalued European countries and boosting wages in undervalued countries. To this end, Germany established a minimum wage, some countries cut the salaries of civil servants, while others lowered their social contributions (the CICE tax credit in France), in the knowledge that other fiscal tools are also possible (see Emmanuel Farhi, Gita Gopinath and Oleg Itskhoki, 2013). The crucial question is therefore: 1) Is an internal devaluation necessary in France, and if so how much? 2) And how could a non-recessionary internal devaluation be implemented without increasing inequality?

So there is clearly a problem if one answers these questions based on the impact of reductions of social charges near the SMIC wage level. This shows the danger of basing oneself solely on results measurable by experiments: it neglects key issues that cannot be decided by this method.

3) The problem of “Keynesianism”

The authors claim that Keynesianism provides fertile soil for negationism even while stating in the book that Keynes’ recipes sometimes work, but not all the time, which any economist would acknowledge. In the absence of clarification, these remarks become problematic. Indeed, recent years (following the 2008 subprime crisis) have witnessed a return of Keynesian approaches, as can be seen in recent publications. I would go so far as to say that we are living in a Keynesian moment, with great financial instability and massive macroeconomic imbalances (Ragot, 2016).

What then is Keynesianism? (It is not, of course, fiscal irresponsibility with ever greater public debt). It is the claim that price movements do not always allow markets to operate normally. Prices move slowly, wages are downwardly rigid, nominal interest rates cannot be very negative, etc. Because of all this, there are demand externalities that justify public intervention to stabilize the economy. The French debate generates concepts like “Keynesianism” and “liberalism” that have no real meaning in economic science. It is the role of the scientist to avoid false debates, not to perpetuate them.

4) Should we listen only to researchers publishing in the top journals?

The public debate differs greatly from the scientific debate in both purpose and form. Cahuc and Zylberberg want to import the hierarchy of academic debate into the public debate. This won’t work.

There will always be a need for non-academic economists to discuss economic issues. The economic situation raises problems where there is no academic consensus. The business press is full of advice from bank economists, markets, institutions and trade unions, all of whom have legitimate, though non-academic, points of view. Newspapers like Alternatives Economiques, quoted by Cahuc and Zylberberg, present their views, as does the Financial Times, which has a mix of genres. Economists without formal academic credentials play a legitimate role in this debate, even if their opinions differ from those of other researchers with longer CVs.

These contradictions are concretely lived at the OFCE, whose mission is to contribute to the public debate with academic rigor. This is a very difficult exercise; it requires knowledge of the data, the legal framework, and the academic literature produced by institutions such as the Treasury, the OECD, the IMF, and the European Commission. Knowledge of the economic literature is essential, but it is far from sufficient to make a useful contribution to the public debate.

The willingness of economists to contribute to the public debate was exemplified in the various petitions around the El Khomry law. These petitions widely debated the effect of redundancy costs on hiring and the form of the employment contract, but not the overturning of norms (a subject that to my knowledge is impossible to evaluate rigorously) – even though this is at the heart of the debate between the government and the trade unions! It is not certain that the idea of a consensus among economists will emerge strengthened by this episode.

5) When a consensus exists in economics, do we have to listen to it?

The consensus before the subprime crisis was that financialization and securitization were factors promoting economic stabilization, because of risk allocation, etc. Microeconomic studies confirmed these intuitions, because they failed to capture the real source of financial instability, which was the correlation of risks in investor portfolios. We now know that the consensus was wrong. Some economists outside the consensus, such as Roubini or Aglietta, and some economics journalists such as The Economist, warned of the destabilizing effects of finance, but they were outside the consensus.

Policy (and the public debate) is forced to ask: what will happen if the consensus is wrong? It has to manage all the risks – that’s its responsibility. The consensus view among economists is frequently not very informative about the diversity of viewpoints and the risks involved. The public voice of economists outside the consensus is necessary and useful. For example, the Nobel Prize in Economics was awarded to Eugene Fama and Robert Schiller, who both studied financial economics. The first asserts that financial markets are efficient, and the second that financial markets generate excessive volatility. Newspapers carry visions outside the consensus, such as Alternatives Economiques in France (at least it’s in the title). These publications are useful to public discussion, precisely because of their openness to debate.

In science, the diversity of methods and knowledge about methodology outside the consensus enrich the debate. For the same reason, I tended to be against the creation of a new section of heterodox economists, supported by the French association of political economists (AFEP), because I see an intellectual cost to the segmentation of the world of economists. For the same reason, giving a consensus among economists the status of truth (Cahuc, Zylberberg, p. 185) is troublesome, because it ignores the contributions of the “minority” effort.

6) “Economic negationism: radicalization of the discourse

The authors castigate ideological criticisms of economics that are unfamiliar with the results or even the practice of economists. The science of economics has strong political implications, and is therefore always attacked when generates disturbing results. Some criticisms lower the intellectual debate to the level of personal insults. A defence of the integrity of economists is welcome, but it requires real learning and modesty to explain what is known and what is not known.

On reading the book by Cahuc and Zylberberg, it seems that the authors take up the arms of their opponents: two camps are defined (real science and deniers), doubts are planted about the intellectual honesty of pseudo-scientists outside the consensus, we proceed by amalgamation, by mixing intellectuals (Sartre) and academic economists. The very title of the book proceeds from great violence. This book is on a slippery slope in the intellectual debate that is heading towards a caricature of debate and verbal abuse. Every economist involved in the public debate has already been insulted by people who disagree with the results presented for purely ideological reasons. Insults need to be fought, but not by suggesting that debate can be avoided due to one’s academic status.

The debate in England on Brexit showed how economists and experts were rejected because of their perceived arrogance. I’m not sure that the scientistic position of the book offers a solution to these developments in the public debate. To quote Angus Deaton once again, in a recent interview he did with the newspaper Le Monde:

“To believe that we have all the data is singularly lacking in humility. … There is certainly a consensus in economics, but its scope is much narrower than economists think.”



Angus Deaton, 2010, “Instruments, Randomization, and Learning about Development“, Journal of Economic Literature, 48, 424-455.

Edouard Challe, Julien Matheron, Xavier Ragot and Juan Rubio-Ramirez, “Precautionary Saving and Aggregate Demand”, Quantitative Economics, forthcoming.

Matthieu Chemin and Etienne Wasmer, 2009 : “Using Alsace-Moselle Local Laws to Build a Difference-in-Differences Estimation Strategy of the Employment Effects of the 35-hour Workweek Regulation in France”Journal of Labor Economics, vol. 27(4), 487-524.

Emmanuel  Farhi, Gita Gopinath and Oleg Itskhoki, 2013, “Fiscal Devaluations”, Review of Economic Studies, 81 (2), 725-760.

James J. Heckman, Lance Lochner and Christopher Taber, 1998, “General-Equilibrium Treatment Effects: A Study of Tuition Policy”, The American Economic Review, 381-386.

Steven D. Levitt and John A. List, 2007, “What Do Laboratory Experiments Measuring Social Preferences Reveal About the Real World?”, Journal of Economic Perspectives, Vol. 21, no. 2, 153-174.

Xavier Ragot, 2016, “Le retour de l’économie Keynésienne“, Revue d’Economie Financière.


[1] Pierre Cahuc and André Zylberberg, Le négationnisme économique et comment s’en débarrasser, Paris, Flammarion, 2016.