On both sides of the Atlantic, it has been an uncomfortable summer for immigrant groups. Here in the United States there have been the quarrels over the "Ground Zero Mosque," “anchor babies,” and Arizona’s new illegal immigrant bill (not to mention yet more calls for the deportation of our “Muslim” president to his “native” Kenya by the surprisingly large proportion of the Republican Party that seems to have taken up permanent residence on Planet Zorg). Meanwhile, French President Nicolas Sarkozy, faced with removal from office by the voters in 2012, has continued to push legislation outlawing the wearing of the burqa in public and acted to expel several hundred Roma to Romania and Bulgaria. This last move in particular has earned him widespread criticism from the media, and widespread support from the French public.

Sarkozy’s actions and France’s continuing struggles with the immigration issue have gotten relatively little coverage in the United States. They are worth taking a closer look at, however, because they starkly illustrate many of the issues that arise from the world-wide movement of populations—issues that the United States will be confronting more and more over the coming decades.

In its attitudes toward foreigners and “immigrant-origin populations” (i.e. both immigrants and the children and grandchildren of immigrants), the French government is increasingly trying to establish French “values” as a basis for policy. For instance, earlier this summer, Interior Minister Brice Hortefeux ordered the deportation of Egyptian Islamist imam Ali Ibrahim El Soudany, claiming that he “despised the values of our society,” and that his message of religious hatred “had nothing to do with religious liberty.” The ban on the burqa is similarly justified by reference not only to human rights, but more nebulously to values such as the importance of face-to-face contact. In this shift, France has followed the lead of countries like the Netherlands, where would-be citizens must now watch a film that shows two men kissing, and a topless woman on a beach, so as to understand Dutch “values.”

This all raises the obvious problem of how national “values” can possibly be defined. Sixty years ago, by most present-day definitions, a large majority of the French (like a large majority in most countries on earth) held homophobic and bigoted attitudes. So should national values depend on shifting majority opinion? If not, who decides their content? Perhaps Sarkozy’s new “Ministry of Immigration, Integration and National Identity”? Moreover, if the values of “the French” can be so neatly packaged, why can the same not be done with other groups, whose values might be judged fundamentally antithetical to “French” ones? What of “Muslim” values, for instance?

Meanwhile, the expulsion of the Roma illustrates the tensions between the politics of immigration and citizenship on the one hand, and the realities of population movements on the other. Sarkozy, in an Arizonan vein, describes the people expelled as threats to public order who, as foreigners, had no right to stay on French soil. Yet, in practice, like most Western countries, France has many categories of resident foreigners (legal immigrants, temporary workers, asylum-seekers, citizens of other EU countries, etc.) who enjoy a wide variety of rights. The Roma expelled this summer are mostly citizens of EU member states Bulgaria and Romania, and, while France had the right to expel them, under EU law, the Roma had the right to re-enter the country the day after their expulsion.

The point, in both cases, is that nationality is not a single, rigidly bounded thing, defined by a particular set of values or a single legal rule. French officials, of all people, should have no trouble understanding this point. In recent years, they have repeatedly changed French nationality law (introducing complex special provisions, for instance, for children born on French soil to foreign parents). And, during the long history of the French overseas empire, their predecessors created a bewildering variety of categories of what amounted to partial or quasi-citizenship, so as to distinguish certain groups under French rule (e.g. Algerian Muslims) from others, and to limit their rights and movement.

Yet, in politics, the temptation is always to divide the world neatly into two parts: “citizens” and “non-citizens,” “us” and “them.” This is hardly, by itself, a bad thing. Democracy requires a clearly bounded community of citizens. And, arguably, elite civil servants in France, with their concern for the construction of a complex, technocratic European super-state, have only fueled populist anger by giving this point too little importance in past years and equating all opposition (including the 2005 referendum vote against the proposed European Constitution) with xenophobia.

Pushing too hard in the other direction, however, quickly devolves into sheer demagoguery. Modern nations are not hermetically walled, ideologically and ethnically homogenous little city states. The complexities of population movements and cultural diversity have to be respected. And Nicolas Sarkozy would do well to remember that strife over “immigrant-origin populations” does not only, or even principally, arise because of conflicts over “values” or an ambiguous legal status. It arises when these groups are actively made to feel alien and unwelcome. Some American politicians could use a refresher on this point as well.

David A. Bell, a contributing editor to The New Republic, teaches history at Princeton.