Assume there is a moral principle indicating that states (or citizens therein) that have adequate (or better) resources have an obligation to aid those in states that have inadequate resources. Such a principle has been defended, of course (see, for example, Charles Beitz’ 1979, esp. 136-143). Importantly, even if such a principle is right, it does not get us directly to a conclusion that states (or citizens therein) that have adequate (or better) resources (like us) have an obligation to aid those in states that have inadequate resources in their society. Although many that write in defense of international redistribution often fail to recognize it, immigration—perhaps coupled with remittances–is an important method of international aid. Hence, it might be enough—indeed, it might be better—to help those in states with inadequate resources to immigrate to a place with better resources (perhaps our own state).
Picture an island devastated by floods and incapable of supporting agriculture. The people on this island need help. Assume we owe them help. If there is a good reason to believe the island cannot be made life-supporting (a dubious situation to be sure), the people have to move and at most our aid should be aiding emigration. More realistically, the island will take some years to be life-sustaining again. Perhaps, then, we ought to help them with temporary food supplements. But perhaps aiding emigration can still satisfy our duty. Certainly, in the more extreme case, where the island can’t support life, we simply cannot conclude that we must sustain the people on the island. Some might bemoan the loss of the “island culture” that would follow mass emigration, but given the extreme nature of the natural disaster, that is unavoidable. The only possibilities are losing the culture and the individuals or losing the culture and saving the individuals by relocating them.
It seems clear, then, that no duty to aid individuals in other societies (or our own) can require, in all cases, that we help them to continue to lead the sorts of lives they previously lived (or would choose to live) in the environment they did (or want to). This does not mean there is no duty to help individuals in other societies; it simply means that sometimes the way to satisfy such a duty would be to help the people move, perhaps to our society.