Utopians don't say, 'The world's corrupt, women make less money, people of color are oppressed at every turn.' You don't list the problems of the world; you describe a world in which those things aren't the case. The critique is implicit and as a result it's kind of a positive critique. You're not listing what's bad, but rather what would be good - you're oriented toward this positive vision.

The fatal flaw of most utopian visions is that they're fundamentally static, and that's not a comfortable place for humans to live. Fourier was very good at imagining a utopia that is constantly changing and very busy, but a vision of paradise that would have been most tantalizing to an underfed overworked factory worker in 1840 doesn't have much appeal in fiction because it's not a story.

Margaret Fuller was already a celebrity, travelling around the world. Emerson, who was the axis around which that whole community turned, just didn't like Fourier's ideas very much. He thought it was all too rigid and programmatic. He said, "Fourier had skipped no fact but one, namely life." He thought it was an inhumane system - the day is scheduled too precisely. He didn't think it would work, and he was right.

The vision shared by both [French utopian] Charles Fourier and Robert Owen was for an entire town to fit into one structure. Owen's design for what he called a "parallelogram" was essentially to have a whole city in one building, laid out around a huge quadrangle. Fourier's scheme was to build a massive Versailles-like structure that he called a "phalanstery." In both cases they had these architectural dreams that we now recognize as pretty unappealing.

There are two instances I studied in which a community moved, amazingly, into an preexisting village built by other, earlier communalists. The Rappites were a German millenarian sect I mostly leave out of the story, even though they are fascinating, because they're focused on salvation and retreating from the world, as opposed to transforming it, like the other groups I write about.

I was really interested in 20th century communalism and alternative communities, the boom of communes in the 60s and 70s. That led me back to the 19th century. I was shocked to find what I would describe as far more utopian ideas in the 19th century than in the 20th century. Not only were the ideas so extreme, but surprising people were adopting them.

I worry that I may have overstated the impact of Civil War on the utopians. By the time the Civil War comes, most of the communities were quite separated from the wider American society. Their rhetoric is still about transforming the world, but they're not having that much traffic with their neighbors.