Title is a little weird, I know. Here's the challenge- sometimes in history a great thinker comes along to call for some philosophical utopia based a particular set of ideas they dream up. And sometimes in history (Lenin with Marx, the Reign of Terror with Rousseau) some revolutionary comes along and tries to apply that philosophy to a new form of government and the results are awful and bloody.
My thought of the day, and my challenge to you, is to imagine a world based on a real world philosophy (any era, though any revolutions based on their work tend to take place at most within the next century) that went largely ignored in the time period of our history. Take this philosophy, then imagine a revolution somewhere in the world seeking to build a better society on those ideals. And then imagine how they manage to utterly screw it up. Explain why the society is built the way it is using the philosophy's base principles, but don't be afraid to introduce some bizarre elements based off those principles (right now I'm reading about Frances Church of the Supreme Being, which pretty much inspired this line of inquiry). Try to keep the ASBs to a minimum, as always, but I encourage you to think as grim and as dark as you can go. Our own history is littered with awful and strange societies built on the bones of good intentioned ideals. Sad fact of human history, you can make a world a very terrible place indeed and remain quite plausible while doing so.