Gaffe or no gaffe, it makes a lot of sense when you think about it. What was Marco Rubio thinking Saturday night in Manchester, New Hampshire? Why would he repeat the same canned talking point four times, even after Chris Christie accused him of constantly repeating his canned talking points? And if he had to repeat a canned talking point during a Republican debate, why on earth would he choose one about how Barack Obama knows what he's doing? The knows-what-he's-doing debacle felt like Rubio's political Fredericksburg, a futile repetitive charge into overwhelming enemy fire. Christie's brutal mockery of Rubio's...