I'm not much for philosophy, so something simple along the lines of believing that I should leave the world a better place than I found it, and there's no reason that should be limited by borders, ethnicity or much else. Also, the idea that I have no obligations to people who are just like me but don't have the same passport is chilling and disturbing in its implications.

Borders are pretty arbitrary things in a lot of cases. There are probably still a few very elderly people alive in the Sud Tirol region of Italy who, as infants, found themselves to be Italian citizens despite not having moved a mile, because Italy managed to beat Austria in WWI. Linguistically, and culturally, they are Austrians in that region (or, in some of the high valleys, Ladin speakers, if we want to start getting into details), and many of them don't really identify with Italy to this day.