Barely a quarter century after the collapse of the Soviet empire, democracy has entered an intense period of public scrutiny. The election of President Donald Trump and the Brexit vote are dramatic moments in a populist uprising against the postwar political consensus of liberal rule. But they are also signposts in a process long in the making, yet perhaps not fully appreciated until the intense electoral upheavals of recent years. The current moment is defined by distrust of the institutional order of democracy and, more fundamentally, of the idea that there is a tomorrow and that the losers of today may unseat the victors in a new round of electoral challenge. At issue across the nuances of the national settings is a deep challenge to the...