Learning from the positions of Nassim N. Taleb and John P. Ioannidis in the COVID-19 debate

25 June 2020

The COVID-19 pandemic has brought a tremendous focus on forecasting as a key component for informing populations and for steering decisions throughout the further development of the pandemics. Forecasting is most often difficult, but in this case, it is made even worse due to e.g. limited knowledge of the underlying processes (it is seen as a new virus), data being collected is possibly unreliable and not representative, the process is not “free” in the sense that by acting based on the forecasts they can be invalidated, etc.

In that context, many have worked hard to analyse data, develop and tune models, communicate forecasts and their uncertainty. Some have additionally contributed to the public debate with the aim to help, to warn and to support with the crisis management process. Two of these voices have been highly visible in the public debate, with seemingly diverging opinions. I am thinking here of John P. Ioannidis and Nassim N. Taleb (arguably two of the greatest living thinkers) holding opposing views about how to deal with the present pandemic and its potentially destructive consequences.

After discussion with my colleague Spyros Makridakis, we realized that organizing a scientific debate between John P. Ioannidis and Nassim N. Taleb would be of great value to the scientific community and to the broad audience. We therefore agreed with them that they would simultaneously prepare two blog posts expressing their views, to be posted at the same time. Starting from the question of whether forecasting for Covid-19 failed, they both unveiled their position. Nassim N. Taleb believes that all efforts and resources should be directed to halt its spread and reduce the number of infected and deaths without any concern about forecasting its future course as the uncertainty of doing so cannot be measured and the risks involved are highly asymmetric. John P. Ioannidis, on the other hand, claims that more reliable information is needed to make multiple billion-dollar decisions and that forecasting has failed us by being too pessimistic about the future growth of the pandemic and by exaggerating its negative effects. Reflecting upon it, they both see a failure in forecasting here, with John P. Ioannidis seeing those forecasts as necessary but unreliable to help policy makers, while Nassim N. Taleb sees the failure in the very idea one may use such (single-valued) forecasts as input to decision-making in view of the properties of the underlying processes.

The International Journal of Forecasting (IJF) is organizing a special section devoted to “Epidemics and forecasting with focus on COVID-19”. Based on their blog posts, John P. Ioannidis and Nassim N. Taleb were given the opportunity to think of each other’s arguments. Consequently, they were invited to write a opinion piece to better detail their views and why they think the opposite side’s views may not be adequate under the current circumstances. These opinion papers will then appear in the IJF, after scientific review by their peers. IJF should reserve the right to publish a closure based on this debate. This debate will not only allow us to better understand the points of view of the two great thinkers but be also left as a guide for how to deal with future pandemics.

Blog posts

Link to the post of John P. Ioannidis (and co-authors, from 11 June 2020): Forecasting for COVID-19 has failed

Link to the post of Nassim N. Taleb (from 11 June 2020): On single point forecasts for fat tailed variables

Opinion papers (preprint version, pending review)

Link to the paper by John P. Ioannidis, Sally Cripps and Martin A. Tanner (from 25 June 2020): Forecasting for COVID-19 has failed

Link to the paper by Nassim N. Taleb, Yaneer Bar-Yam and Pasquale Cirillo (from 25 June 2020): On single point forecasts for fat tailed variables

Pierre Pinson & Spyros Makridakis

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