Last night's performance by Biden – capering, giggling, near-maniacal opera buffa – was targeted in one place: a dispirited, demoralized Democratic base on the edge of panic. Paul Ryan was businesslike, steady, and on-point. He hit solid doubles all night, and that's all he needed to do. If he'd been as amped and manic as Biden, it would have been a political and imaging disaster. Biden aimed to throw the Obama base a lifeline. He fed the Kos Kidz desperate need to see some fight, but at the cost of his remaining (and mostly notional) dignity. If you want a...