What ails our politics? Polarization, incivility, and partisan squabbling are weakening our system’s ability to respond to major national crises. Not that this is new. Our political history is littered with stories of gridlock, bitter rhetoric, and seemingly intractable disagreements. Even so, recent events provide cause for concern: a congressman shouting “You lie!” during a presidential address, a 2009 bill proposing modest steps to address global warming that couldn’t get passed even though it was supported by the president and a clear majority in both houses of Congress, a once-routine debt-ceiling vote that threatened a devastating federal default. Why this, why now?