The hero of James Joyce’s Finnegans Wake is a certain Humphrey Chimpden Earwicker, HCE for short, whose dreaming mind becomes the psychological space of the Wake’s drama. If Ulysses’s Leopold Bloom is everyday man, then HCE is everynight man. Thus the epithet Joyce gives him in chapter two: “Here Comes Everybody.” The initials HCE were the “normative letters,” Joyce said, of a universal dreaming figure, reliving in a single night’s sleep the whole of human history. “An imposing everybody he always indeed looked,” Joyce jokes of Earwicker, “constantly the same as and equal to himself and magnificently well worthy of any and all such universalization.”

For a while I dreamed of writing a book with the title Here Comes Everybody. An urban book, because today urban life is the social environment to which everybody is coming. Only a few decades ago, a majority of the world’s population lived in the countryside; today, most people live in cities, and soon that majority is set to become almost everybody; billions of people, inhabiting a vast global banlieue. In 2008, Clay Shirky, a communications professor at New York University, beat me to it, publishing his Here Comes Everybody with the intriguing subtitle The Power of Organizing Without Organizations. Here Comes Everybody is an artless book, un-Joycean in its lack of existential depth. Yet perhaps lack of depth is the point, in Shirky’s account of the new forms of sociability engendered by a digital age, a world in which everybody is getting together on Facebook and Twitter.

Here Comes Everybody quickly became a bestselling bible for the social-media movement, with a thesis that could apply as much to the corporate sector as to grassroots activism. Shirky’s appeal was his inclusive “everybody”: social media had the power to deprofessionalize select sectors, such as journalism, and create collaborative work for “ordinary” nonspecialist people. Groups could no...