Robert Nozick provides this version of the Hart–Rawls principle of fairness:

The principle of fairness has encountered vigorous objections. Some deny that the principle of fairness really justifies the moral obligations it proposes. Others deny that any obligations generated according to the terms of the principle are permissibly enforceable. One important recent objection maintains that forcing people to comply with the principle of fairness would be wrongfully paternalistic. Untangling this objection requires clarification as to what should count as a paternalistic restriction and what makes such restriction wrongful when it is that.

The moral appeal of the principle of fairness withstands these criticisms. Or so I shall argue. My procedure will be to consider objections one by one and either argue against the criticism or indicate how a minor reformulation of the principle accommodates the concern. The appeal throughout is to intuitive plausibility; I venture no deep explanation of what might justify the principle. To my mind its attraction is simple and lies on the surface. The core idea is roughly that it is morally wrong to free ride on the cooperative efforts of others, benefiting from their sacrifices without doing one’s fair share to contribute, at least when one’s failure to contribute would leave other contributors worse off. (I do not try to defend the principle of fairness against a deflationary act-consequentialist account of the supposed obligations it generates. This chapter aims to contribute towards the development of the most promising non-consequentialist moral theory.)