From a rational perspective, joining a protest rally is like voting: a complete waste of time. The odds that your voice or your protest sign will make a difference are no better than the odds that your vote will change an election. Yet people do join protests, and people do vote. They do these things not to advance their rational self-interest but to express moral passions and moral identities. In a feature story from our January 2012 issue, University of Virginia psychology professor Jonathan Haidt explains what the protest signs at Zuccotti Park say about the moral foundations of the Occupy Wall Street protestors.