01180nas a2200109   4500008004100000245008600041210006900127260001200196520077100208100002200979856006901001       2014                        eng d00aCommons, Social Choice and Welfare: the limits of private Property Rights system.0 aCommons Social Choice and Welfare the limits of private Property  aLeipzig3 aBased on an approach related to Williamson´s and Ostrom´s works, this paper aims to analyze the economic implications of the development of different systems of Commons and collective Property Rights. In the first part, I will show how the economic literature conceives the problem of commons and anticommons. In the second part, after some methodological considerations, I will specify the different elements necessary to build a function of collective welfare, I will define the concept of viability of a particular mode of governance and show why, when the transaction costs are positive, the governance based on private negotiation is not systematically the most efficient mechanism in terms of social welfare. Keywords: Commons- Social Choice- Property Rights1 aHerscovici, Alain  uhttps://degrowth.community/conference2014/scientific-papers/3217