  The most popular argument for the permissibility and importance of closing borders to outsiders is that this exclusion is necessary in order to preserve a state’s distinctive culture. The appeal of cultural continuity is easy to appreciate. As David Miller explains, “the public culture of their country is something that people have an interest in controlling: they want to be able to shape the way that their nation develops, including the values that are contained in the public culture. They may not of course succeed: valued cultural features can be eroded by economic and other forces that evade political control. But they may certainly have good reason to try, and in particular to try to maintain cultural continuity over time, so that they can see themselves as the bearers of an identifiable cultural tradition that stretches backward historically.” (Miller 2005: 200) Think of the United States, for instance. If the US placed no limits on immigration from Canada, it is clear neither how many Canadians would move south, nor whether their migration would have a discernible affect upon American culture. If the United States did not limit immigration from Mexico, on the other hand, it seems almost certain that much larger numbers of Mexicans would migrate north and that the changes to American culture would be regarded by many as rapid and dramatic. (Huntington 2005) If so, it seems likely that open borders would quickly lead to changes that would leave many Americans less comfortable in their own homeland. Given this, the concern to preserve one’s native culture seems to provide a reasonable justification for restricting immigration.