Cultural confidence and the radical cringe

Earlier this week, I was rereading a book from one of my favorite living scholars, and came across this little gem:

 "[A]s the age of the Ottoman Empire's preeminence in military, cultural, and scientific achievements gave way to centuries in which European countries overtook them in all these respects, the confident and cosmopolitan toleration of minorities within the Ottoman Empire gave way to an era of Ottoman anxiety about dangers from without and within, and to xenophobia that greatly restricted and endangered Jews and other minorities."
– Thomas Sowell, Economic Facts and Fallacies

Conservatives can boast of few advocates as brilliant as Thomas Sowell and there are few scholars of any ideological persuasion matching his depth and breadth.  I assume, therefore, that that those who seriously support free markets and free peoples must take Sowell's ideas seriously.  What Sowell implies in the excerpt above is that a loss of civilizational confidence may trigger a wave of xenophobia directed at ethnic minorities within one's borders.  He expands on this idea elsewhere in his books, as well as online essays such as this one in which Sowell points out that “When people are confronted with a choice between hating themselves for their stagnation or hating others for their progress, they seldom hate themselves” but rather “become hostile to the newcomers and . . . believe that they [the immigrants] have done something illegitimate to achieve success.”

What, if anything, do these generalizations from an eminent scholar of history and economics tell us about our most recent wave of anti-immigrant hysteria?  Our current mania has resulted in the formation of a citizen militia to keep watch on the southern border, as well as a bevy of state laws designed to make our land less hospitable to the those who cross borders without first consulting with the central bureaucracy in order to get their official papers signed and sealed, not to mention the creation of a woefully unregulated market in human trafficking. 

Perhaps Sowell’s insights are not applicable here.  Maybe anti-immigrant activists and their sympathizers are not generally motivated by the fear that our nation will cease to be incomparably great in military, cultural, economic, and scientific domains.  Maybe, though, Sowell really is on to something here.  Perhaps it is not merely the direct economic threat from the bilingual folks who did my landscaping and my roof, but also the more generalized anxiety that America (like Rush Limbaugh and Lou Dobbs) has gone well past its prime and will never again be as powerful and preeminent as it once was.