In 1937, Ronald Coase answered one of the most perplexing questions in economics: if markets are so great, why do organizations exist? Why don’t people just buy and sell their own services in a market instead? Coase, who won the 1991 Nobel Prize in Economics, answered the question by noting a market’s transaction costs: buyers and sellers need to find one another, then reach agreement, and so on. The Coase theorem implies that if these transaction costs are low enough, direct markets of individuals make a whole lot of sense. But if they are too high, it makes more sense to get the job done by an organization that hires people.

Economists have long understood the corollary concept of Coase’s ceiling, a point above which organizations collapse under their own weight—where hiring someone, however competent, means more work for everyone else than the new hire contributes. Software projects often bump their heads against Coase’s ceiling: recall Frederick P. Brooks Jr.’s seminal study, The Mythical Man-Month (Addison-Wesley, 1975), which showed how adding another person onto a project can slow progress and increase errors.

What’s new is something consultant and social technologist Clay Shirky calls ”Coase’s Floor,” below which we find projects and activities that aren’t worth their organizational costs—things so esoteric, so frivolous, so nonsensical, or just so thoroughly unimportant that no organization, large or small, would ever bother with them. Things that you shake your head at when you see them and think, ”That’s ridiculous.”

Sounds a lot like the Internet, doesn’t it? And that’s precisely Shirky’s point. His new book, Here Comes Everybody: The Power of Organizing Without Organizations , explores a world where organizational costs are close to zero and where ad hoc, loosely connected groups of unpaid amateurs can create an encyclopedia larger than the Britannica and a computer operating system to challenge Microsoft’s.

Shirky teaches at New York University’s Interactive Telecommunications Program, but this is no academic book. Sacrificing rigor for readability, Here Comes Everybody is an entertaining as well as informative romp through some of the Internet’s signal moments—the Howard Dean phenomenon, Belarusian protests organized on LiveJournal, the lost cellphone of a woman named Ivanna, Meetup.com, flash mobs, Twitter, and more—which Shirky uses to illustrate his points.

The book is filled with bits of insight and common sense, explaining why young people take better advantage of social tools, how the Internet affects social change, and how most Internet discourse falls somewhere between dinnertime conversation and publishing.

Shirky notes that ”most user-generated content isn’t ’content’ at all, in the sense of being created for general consumption, any more than a phone call between you and a sibling is ’family-generated content.’ Most of what gets created on any given day is just the ordinary stuff of life—gossip, little updates, thinking out loud—but now it’s done in the same medium as professionally produced material. Unlike professionally produced material, however, Internet content can be organized after the fact.”