No society can, of course, be a scheme of coopera- tion which men enter voluntarily in a literal sense; each person finds himself placed at birth in some particular position in some particular society, and the nature of this position materially affects his life pros- pects. Yet a society satisfying the principles of justice as fairness comes as close as a society can to being a voluntary scheme, for it meets the principles which free and equal persons would assent to under circum- stances that are fair. In this sense its members are autonomous and the obligations they recognize self-imposed.