CHINA IS shakily authoritarian while India is a stable democracy—indeed, the world’s largest. So goes the cliché, and it is true, up to a point. But there is a growing resemblance between the two countries. A decade after we were told that China and India were “flattening” the world, expediting a historically inevitable shift of power from West to East, their political institutions and original nation-building ideologies face a profound crisis of legitimacy. Both countries, encumbered with dynastic elites and crony capitalists, are struggling to persuasively reaffirm their founding commitments to mass welfare. Protests against corruption and widening inequality rage across their vast territories, while their economies slow dramatically.