My ethical intuitions are strongly cosmopolitan. By that I mean it seems obvious to me that moral and ethical principles are not constrained by distance or borders. You might agree, but in reality the way in which we live our lives suggests that most of us hold the opposite view.
What does the cosmopolitan intuition imply? Firstly, it implies that the fact that an individual is born or lives on the other side of the world is morally insignificant. My prima facie obligations to them are identical to my prima facie obligations to my neighbour. By prima facie obligations I mean those that arise from our shared humanity (however that is conceived). You might that that we don't have any prima facie obligations that arise from shared humanity, and if so, then I'm not engaging with you here. I'm assuming that most people accept that there are at least certain limitations on our behaviour towards others, such as a prohibition against wrongful killing. I cannot use the fact that someone belongs to a different nation to me as a basic moral reason for acting (or not acting) in a certain way towards them. Such facts (often called relational) are not moral relevant - they can't be used in moral reasoning at the fundamental level.
What does the cosmopolitan intuition not imply? Importantly, it does not imply that I am obligated to treat everyone exactly the same. I do not have to let my family 'go without' if devoting my time and energy to relieving a foreign famine would save more lives, or produce more utility. To put this a different way, it doesn't imply that relational facts can't be morally relevant at the non-fundamental, or applied, level. I just need a good reason why the particular relational fact is relevant in those circumstances. Most people will agree that the fact that someone is a member of my family is in many circumstances relevant to my action. However there are some circumstances in which it shouldn't be - when interviewing for a job for example. My reason for allowing the relational fact in must be independent at the pain of circularity. Anyone who is familiar with Bernard Williams will cry at this point that this demands 'one thought too many' - unfortunately my reply to that charge will have to wait for another day.