Why social media isn't

[Commentary] Despite all the newfangled ways we've developed to communicate across all sorts of boundaries, we're increasingly deciding to talk, tweet and Facebook with folks who are more or less like ourselves.

We live in an age in which overarching collective identities and institutions are collapsing in favor of narrower groupings by affinity. Think of the decline of network television, the rise of political independents, and the nichification of politics and the marketplace. While social media enthusiasts love to crow about the flowering of a million voices, I worry about the erosion of the social contract and national consensus.