**Les Cahiers de Recherche - HEC Paris**
# No 955:

The relevance of utilirianism

*Philipppe Mongin *()

* and Marc Fleurbaey*
**Abstract:** Author's abstract. Harsanyi invested his Aggregation
Theorem and Impartial Observer Theorem with deep utilitarian sense, but Sen
redescribed them as "representation theorems" with little ethical import.
This negative view has gained wide acquiescence in economics. Against it,
we support the utilitarian interpretation by a novel argument relative to
the Aggregation Theorem. We suppose that a utilitarian observer evaluates
non-risky alternatives by the sum of individual utilities and investigate
his von Neumann-Morgenstern (VNM) preference on risky alternatives. Adding
some technical assumptions to Harsanyi’s, we conclude that (i) this
observer would use the utility sum as a VNM utility function, and
crucially, (ii) any social observer would evaluate both risky and non-risky
alternatives in terms of a weighted utility sum. Hence, pace Sen, VNM
theory can give some interesting support to utilitarianism. The argument is
conveyed by means of three theorems that encapsulate Harsanyi’s original
one as a particular step.

**Keywords:** utilitarianism; aggregation theorem; impartial observer theorem; cardinal utility; vnm utility; harsanyi; sen.; (follow links to similar papers)

26 pages, November 26, 2011

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