Cities, thinks the political theorist Benjamin Barber, can save democracy. In his new book “If Mayors Ruled the World: Dysfunctional Nations, Rising Cities“, Barber argues that only cities are capable of reconnecting “participation, which is local, with power, which is central”. Nation states used to do that, but they have become too large to sustain the kind of “bottom-up citizenship, civil society and voluntary community” which he thinks, following John Dewey, is the essence of democracy. There’s a global dimension to this, too. If nation states are too big to nourish genuinely participatory democracy, they’re also too small to meet the challenges of global power in all its dimensions. The alternative, Barber says, to inefficient supra-national institutions composed of nation states pursuing their own interests is a “cosmopolitan” global system of networked urban centres, a “global parliament of mayors”. That may sound impossibly utopian, but Barber makes a pretty convincing fist of showing why it might just work.