Stoking fears of foreigners is perhaps the oldest trick in the political playbook. From Benjamin Franklin's 1751 warning that Pennsylvania would soon become a "Colony of Aliens, who will shortly be so numerous as to Germanize us instead of our Anglifying them," to modern-day Dutch politician Geert Wilders, who laments a coming "Eurabia" dominated by Islam, playing up the threat posed by new arrivals is a surefire, if cynical, way to win votes.
Why do such arguments still work? Western countries have absorbed wave after wave of immigration without civilizational collapse. How can Americans, whose ancestors were accused of importing German fascism, Italian Catholicism, or Jewish socialism, take seriously the threat of "creeping sharia" or a Mexican reconquista? If one judges by recent studies, it's pretty hard to stop the cycle of fear.
Paradoxically, anti-immigrant prejudices are often based on flawed premises, but exposure to more information doesn't necessarily change them. A 2011 study by political scientists Jennifer Fitzgerald, K. Amber Curtis, and Catherine L. Corliss found that anti-immigrant attitudes in Germany were far more closely correlated to fears of crime than cultural concerns, even though first-generation immigrants in Germany are no more likely than natives to be criminals. Surprisingly, they also found that Germans who are more politically engaged and consume more news are especially likely to make the dubious linkage between immigrants and crime, an effect they attribute to the anti-immigrant rhetoric employed by the media and politicians -- including Chancellor Angela Merkel, who said last year (incorrectly) that Germans "must accept that the level of crime in immigrant youth is particularly high." Surely it's no coincidence that fears of crime by immigrants increase during election years.
Such fears are often driven by factors that have nothing to do with the immigrant communities in question. A 2011 study, for example, found that anti-Latino sentiment in the United States jumped sharply following the 9/11 attacks -- though, of course, no Latinos were responsible.
This might seem odd in diverse, tolerant cities such as New York, but research finds that natives don't necessarily react better to immigrants when they live among more of them. French researchers conducted a game experiment with groups of "rooted" French and Muslims, finding that the generosity of the rooted French toward Muslims decreased as the number of Muslims in the group increased. The researchers named this the "Hortefeux effect" after former French Interior Minister Brice Hortefeux, who said of Arabs in 2009, "When there's one, that's OK. It's when there's a lot of them that there are problems."
Of course, attitudes do change eventually. In today's America, an Anglo-Saxon describing people of German descent as "Palatine Boors," as Ben Franklin did in the 18th century, would be viewed more as a quaint eccentric than a dangerous racist. But it's cold comfort to today's new arrivals to know that the only thing that may change attitudes is the passage of centuries.