Even though it seems natural to think the difference between being born in the United States and being born in Sierra Leone is just as arbitrary, just as unworthy to be the basis for a human being's lot in life as race or sex or religion, his project of forming a just society took the nation-state as its basic unit. Insofar as Rawls and other theorists did approach the question of international justice, it was typically in a way that presupposed the salience of the nation-state and guaranteed that unit considerable autonomy. The result is that in philosophy, as in international law, we now have a well-articulated set of universal norms protecting some aspects of human life across national boundary lines. But few recent philosophers have had anything at all to say about the egregious material inequalities among nations. International law has been similarly silent on obligations of material aid across national boundaries.
Justice requires more.
We give lip service to the idea that respect for human dignity is a fundamental moral requirement, and yet we daily allow human dignity to be violated by poverty, illiteracy, unequal liberty and other nation-based inequalities. But because we are at a loss to say what those obligations are, we find it easier to lapse into inattention. Good theory helps people get a handle on their choices, making it more difficult for them to ignore their obligations. Philosophical theories of global justice are, then, badly needed to give guidance to personal reflection and public policy.