I like Richard Chappell's way of putting the point I was trying to make about the allocation of citizenships:
… it's not as though citizenship is some positive entity that we're simply omitting to provide. A non-citizen is not lacking in any intrinsic capacity. What citizenship provides is permission — it simply serves to remove the obstructions we would otherwise place in their way. In other words, social resources are liberties, and arguably should be considered the natural 'default' or baseline position. Citizenship isn't something we grant; it's something we cease to deny.
However, I'm not sure the last claim can be right. I can't see how citizenship can be a natural default. There are no states in nature.
Suppose there is a naturally occurring orchard that is no one's property. If someone put a fence around the orchard, or divided it into multiple fenced parcels, and sought to exclude others from the fruit, they would need a good justification. I think there can be a good justification, which is provided by David Schmidtz in his paper “The Institution of Property.” I think it can be tempting to see the world as a big commons, like the orchard, and the boundaries of nation states as parcels that fence in the commons. Actually, I think that's exactly the way to think about it. Then, one might try to justify the system of nation states on analogy with the justification of property. But the justification of parceling off the commons is that often this is a necessary condition for leaving enough and as good for others–otherwise, the fruit may just disappear forever. Unless we can assign certain rights to exclude, we get all consumption and no production. Soon enough, there is nothing left to consume, and people die or suffer from deprivation. There is more to consume if there is more produced, and since exclusion is a condition of production, people need a certain system of exclusion: property rights. Are states like that?
Mostly, no. Now, a certain system of norms and institutions can be may be extremely beneficial to the people living under them. If the integrity of that system requires exclusion, than it might be justified. I take it that this is what some conservatives have in mind when they argue that if the U.S. lets in too many Mexicans, the norms that undergird broadly beneficial American institutions will weaken to the general detriminent. So, the preservation of the conditions for mutually beneficial order within a certain geographical region may be a justification for exclusion — if only as a means of keeping the in-flow of persons well-regulated. There may be no justification for keeping someone out, period, but there may be justification for making them wait in line. How fast the line should move will be an empirical matter of the robustness of the mutually beneficial institutions inside the fence to new entrants with different characteristics.
But that kind of thinking doesn't get us anywhere near the justification of the system of states. Why do we think we can justify the nation state, but must justify the system of property? Many, perhaps most, people are made worse off by the fact that they are both fenced inside the state where they were born, and fenced out of other states. If it doesn't make most people better off, the system of states is hardly justified. In light of the fact that most people don't benefit from the system of internal entrapment and external exclusion that characterizes the global system of states — a rather obvious fact when you think about it for a second — don't we have to reconsider the previous argument for exclusion?
If there is an ongoing positive-sum game inside the fence, which billions outside the fence would like to come inside and play, then what should we say to them? If additional players to the positive sum game reduces the payoffs to the incumbent players, then the incumbent players will not want to let anyone through the fence. But if the benefit to new players is greater than the loss to incumbent players, shouldn't we take that into account? I grasp and agree with the idea that in-flow needs to be well-regulated to avoid the erosion of the institutions that make a place attractive in the first place. Yet the idea that we discount the potentional welfare gains to people outside the fence by bringing them inside simply because they are not already inside the fence strikes me as monstrously, stupefyingly immoral.
Take any plausible liberal theory of the moral legitimacy of the nation-state. It will turn out that all but a handful of states fail even a fairly generous test of legitimacy. How, then, can successfully liberal states justify their complicity in an overall system that literally traps billions of people in poverty and injustice? I can't see how the system of states can possibly be justified without some kind of mutual assurance of mobility and the kind of jurisdictional competition that creates.
Anyway, back to the point about the allocation of citizenship… Citizenship is conceptually tied to the idea of a state. A state is like a club and your citizenship is like a membership. The problem is that the system of clubs has no justfication. The few morally decent clubs have no moral basis for not making more many more memberships available, and, insofar as they wield influence on indecent clubs, are morally obliged to not assist them in fencing their immiserated and oppressed people in, and may be obliged to assist citizens of illegitimate states (indecent clubs) in gaining membership to some decent club or other.