Le paradoxe libéral-parétien : un second théorème d'impossibilité dû aux effets d'indépendance

The aim of this article is to take stock of the Sen liberal paradox debate so as to identify a number of approaches to a credible resolution. We demonstrate that, when authors propose solutions to the Pareto-liberal conflict, they ultimately show a marked conceptual preference for one or another condition that in the end weakens the competing condition. We argue that these attempts, none of which is truly satisfactory, reveal the independence effects at the root of the paradox. Explicitly detailed by some, intuited by others, these effects are rarely taken into account globally, for if they were we would then be led to reconsider formalism as a whole, and not merely one condition or another. After Arrow's, the Pareto-liberal paradox can thus be regarded as a second impossibility theorem, once more affirming the failure of the new welfare economics.