Preferences, social choice and theories of justice

Abstract

[en] This work is an introduction to Social Choice Theory and Distributive Justice. It aims to set under which conditions does exist a method to aggregate individual preferences. We first model individual behaviour in decision making taking into account preferences and utilities, and also choice behaviour. The objective is to understand how collective choice can be done. Then we formulate and prove Arrow’s impossibility theorem, which states that, under certain (and reasonable) conditions, it is impossible to find an aggregation system. We also present some ways to loosen hypothesis in order to avoid this impossibility. Finally, we redefine our whole framework to allow interpersonal comparisons. This lets us characterize two main ways of social deciding: the leximin principle and the utilitarian rule.