The construction of the European Union is an attempt to protect a "European identity." Aging and mass immigration are bringing big changes to Europe. There is no prospect of constraining that change unless the continent’s social contract (starting with its welfare states) is reformed. But Europeans fear that such reforms threaten Europe with "Americanization." What is European identity? How much of it can reasonably be preserved? This month marks the 100th anniversary of the birth of the French political scientist, philosopher, sociologist and historian Raymond Aron. For all his multidisciplinary brilliance, his main legacy is what one of his more celebrated students recently called "intellectual hygiene"—a rigorous preference for uncomfortable reality over ideological wishful thinking. It is through his work that we get the best idea of how much of "Europe" is reality, how much myth, and how much will remain in fifty years.

Christopher Caldwell is a senior editor at the Weekly Standard, a columnist for the Financial Times and a contributing writer for the New York Times magazine.