It is significant […] that whereas it is easy to find thinkers from different times and places to whom it is intuitively obvious that we have special obligations to those of our own religion, race, or ethnic affiliation, this does not seems so obvious to contemporary ethicists and political theorists. If the strength of intuitions favoring special obligations based on racial and religious affinity is not sufficient grounds for accepting them, then the strength of our intuitions about, say, special obligations based on fellow-citizenship, should also not be sufficient reason for accepting them. Instead, we need another test of whether they should be accepted.

Peter Singer, ‘Outsiders: Our Obligations to those beyond Our Borders’, in Deen K. Chatterjee (ed.), The Ethics of Assistance: Morality and the Distant Needy, Cambridge, 2004, pp. 13-14