Political liberals like John Rawls, Charles Larmore, Josh Cohen, and Martha Nussbaum endorse the Reciprocity Principle: important political decisions must be justifiable using considerations that reasonable citizens can expect each other to accept. But many political liberals have had little to say about what justifies the Reciprocity Principle. I'll argue that this is a problem, and then I'll sketch a strategy for resolving the problem by appealing to the value of political community. According to this view, the Reciprocity Principle is justified because compliance with the principle promotes attractive relationships between citizens.

I'll focus in on the connection between the Reciprocity Principle and the relation of civic friendship, which is present when citizens care that their political activities benefit one another on mutually acknowledged terms. Then I’ll explain how religious, philosophical, ethnic, and cultural pluralism can threaten the formation of civic friendship, and how citizens’ compliance with the Reciprocity Principle can contribute to resolving that threat. The result is one piece in a larger attempt to justify the Reciprocity Principle as a principle of political community for pluralistic societies.