The 21st century, then, poses the prospect of retro-revolution, with populism challenging meritocracy. Unlike earlier revolutions, which expanded political and social rights associated with rising mass prosperity, insurgent populism grows in response to economic decline associated with globalization, financialization, and information technology, raising the specter of derogation of democratic capitalism as the default political economy. Berlin, whose family fled post-revolutionary Russia, borrowed from John Stuart Mill's On Liberty, which appeared a century earlier, establishing what would become a European understanding of liberalism, later morphing into American libertarianism. Negative liberty was the core of a properly liberal political creed. A mass movement of American college students reprised revolutions that had suborned democracy for tyranny, representing a promiscuous intellectualism.