Lecture by JeanPierre Dupuy

Tuesday 30th May, at 6pm, free entry

IAS-Nantes, Simone Weil Amphitheater

Indeterminacy – a radical form of uncertainty. The case of nuclear deterrence

Lecture by Jean-Pierre Dupuy,Professor at the University of Stanford.

In 1921, in relation to rational apprehension of the future, the American economist Frank Knight introduced the concept of radical uncertainty by making a distinction between risk, which is comprehensible in terms of likelihood, and uncertainty, which is irreducible in calculating chance. Keynes used this distinction again in 1936 in his Theory, but that was the end of its story. After the second world war, Leonard Savage’s concept of subjective probability and Bayes’ theorem looked set to sweep the table, as economists and other decision-makers could not come to terms with the rather hazy idea of radical uncertainty.

I will attempt to give this idea form and substance by using the concept of indeterminacy in the sense intended by quantum physicist Werner Heisenberg in his principle of Unbestimmtheit, which should not be translated as “principle of uncertainty” but rather as “principle of indeterminacy”. The probable is based on the disjuncture between possible futures (there will be a naval battle tomorrow or there won’t be), whereas the undetermined must be thought of in terms of the superposition of conflicting states: Schrödinger’s poor cat is simultaneously dead and alive as long as we have not actually witnessed its state.

The main part of the talk will consist of illustrating this idea with the example of what has been called, for want of a better term, the “cold war” or “nuclear peace”, and attempting to shed light on the central paradox of nuclear deterrence: how can we explain the fact that for over forty years, two superpowers have constantly threatened each other with nuclear annihilation without this actually happening.