Secessions and federations, an economic analysis of political fragmentation.

Summary Secession is understood here as the action taken by a part of the population of a political jurisdiction to separate from it in order to form another jurisdiction of the same competence as the first. A political jurisdiction is a territorially identified group of individuals who finance and share a common public good. The notion of jurisdiction is similar to that of political sovereignty. Under the hypothesis of a multiplicity of public goods, the secession thus defined allows a jurisdiction to acquire a certain autonomy (only certain public goods are concerned) or its independence (all political decisions fall under the new jurisdiction). In addition to the introduction and conclusion, this thesis has four chapters. The first is a review of the literature. The next chapters are three original models. These aim to highlight some of the mechanisms that contribute to secession in a country composed of two regions with exogenous borders. The heterogeneity of the population is the centrifugal force that drives political fragmentation in a democratic context. It is opposed to various centripetal forces that induce the centralization of political decisions, such as economies of scale in the production of public goods, the size of the national market determining individual income, etc.