Equilibrium and efficiency with property rights and local consumption externalities

There is no mechanism that guarantees existence and Pareto optimality of equilibrium in all situations if each individual has limited property rights and a utility function that depends upon his neighbour's consumption. This is true under virtually any assumption about coalition formation. Therefore, Sen's paradox of the Paretian liberal is confirmed in an economic exchange setting with limited externalitities, and Coase's conjecture on the efficiency of bargaining with complete information is denied.David Austen-Smith, Michael Peters, and Jonathan Riley provided helpful comments at various stages. I am grateful for their suggestions and for the financial support of the Social Sciences and Humanities Research Council (Canada). Responsibility for the paper's deficiencies rests with the author, of course.