The principle of fairness is a moral principle which states that individuals are under an obligation to contribute towards beneficial cooperative projects. It has been appealed to in arguing that citizens are obligated to pay for public goods that their government supplies. Yet the principle has faced a number of powerful objections, most notably those of Robert Nozick. In responding to some of these objections, proponents of the principle have placed a number of conditions on its application. However, by doing (...) so, they have reduced the number of public goods that the principle can explain obligations to contribute towards, and consequently limited its relevance to questions of political obligation. I argue here that a more permissive version of the principle, with fewer conditions on its application, will perform equally well in responding to Nozick's objections. This opens up the possibility of a theory of political obligation that relies more heavily on the principle of fairness than has previously been thought possible. (shrink)