'Hard Problems' history and articles

In 1900 German mathematician David Hilbert laid down a challenge to future generations: He formulated 23 mathematical problems, all fundamentally important, all extremely difficult. A hundred some years later, ten of the twenty-three have been fully solved; eleven are partly solved or simply cannot be solved; and two remain at large. Hilbert's problems had a huge influence on mathematics throughout the 20th century and continue to influence the field today.

We have taken Professor Hilbert’s vision one step further, shifting his lens to a new field of inquiry: the social sciences. After a year and a half of planning with the non-profit Indira Foundation, which initiated the effort and also provided financial support, the Division of Social Science in the Faculty of Arts and Sciences at Harvard convened a panel of multidisciplinary experts to propose and prioritize an analogous set of the world’s hardest unsolved problems in social science. We hoped that this project would not only inspire new research, but also serve to focus funding and inform policy.

Keep in mind that Hilbert had it comparatively easy – our challenges are in some ways more fundamental than those faced in mathematics. For instance: What is “social science”? It obviously includes fields such as Economics, Sociology, and Political Science, where societies are studied. And it includes parts of Anthropology, Psychology, and History – but where, precisely, do we draw the line? Can we even draw a line? What is a “problem” in Social Science? It's obvious what a problem in math is, but less obvious here. How can we tell whether what look like two different problems are really distinct, as opposed to being different manifestations of the same underlying problem? How do we decide what makes a problem difficult? And how do we relate difficulty to importance? Finally, how do we know whether a proposed solution is actually a solution?

Avi Nash (Indira Foundation) and Stephen M. Kosslyn (Harvard University)
Photo by Angela Alberti.

Polling process and results

   (J. M. Shephard, 6 May 2011)

Harvard Magazine
   (27 April 2011)

   (J. Giles, 2 February 2011)


Harvard Magazine
   (27 April 2010)

Wall Street Journal
   (C. F. Chabris, 16 April 2010)

Harvard Alumni Affairs &

   (L. D. Carlisle, 16 April 2010)

Harvard Science
   (A. Alberti, 14 April 2010)

Harvard Crimson
   (B. B. Depena, 12 April 2010)

Dienekes' Anthropology blog 

 International Political Economy
   UNC blog
(see also here)

 Bogleheads Investment Forum

 Savage Minds

 Publishing Archeology blog

 Chris Blattman's blog

 Orgtheory.net blog