Democratic Forking: Choosing Sides with Social Choice

Any community in which membership is voluntary may eventually break apart, or fork. For example, forks may occur in political parties, business partnerships, social groups, and cryptocurrencies. Forking may be the product of informal social processes or the organized action of an aggrieved minority or an oppressive majority. The aim of this paper is to provide a social choice framework in which agents can report preferences not only over a set of alternatives, but also over the possible forks that may occur in the face of disagreement. We study the resulting social choice setting, concentrating on stability issues, preference elicitation and strategy-proofness.