The second-term curse goes like this: A president (e.g., Richard Nixon, Ronald Reagan, Bill Clinton, George W. Bush, and so on) wins reelection, but then his presidency implodes over the next four years — mired in scandals or disasters such as Watergate, Iran-Contra, Monica Lewinsky, the Iraqi insurgency, and Hurricane Katrina. Apparently, like tragic Greek heroes, administrations grow arrogant after their reelection wins. They believe that they are invincible and that their public approval is permanent rather than fickle. The result is that Nemesis zeroes in on their fatal conceit and with a boom corrects their hubris. Or is the...