Americans are very politically divided. Democrats say we need a more powerful welfare state while Republicans say we need to maintain the free market. The struggle, we are constantly informed, is one of ideas. And that it is in the worst possible sense, for neither the Democrats nor Republicans seem interested in evidence. They don’t want the facts to get in the way of their arguments.In his remarkable book The Political Economy of Human Happiness: How Voters’ Choices Determine the Quality of Life (Cambridge University Press, 2013), Benjamin Radcliff provides facts that should help both Democrats and Republicans, despite their many differences, decide how to proceed. He asks a simple, compelling question: do conservative or liberal public policies make people happier? After an extensive and sophisticated analysis of the data, he reaches an equally simple, compelling answer: liberal policies do.Radcliff is a great friend of the free market; it is obvious, he says, that capitalism is the best economic system we have at our disposal. But he is also pragmatic: all the evidence shows that free markets alone don’t make people as happy as markets combined with robust welfare and labor-protection programs. There is a lesson here for both Democrats and Republicans. Listen up.