MEETING WITH VOTERS in an Andover living room last month, US Senate candidate Elizabeth Warren vigorously challenged the idea that Obama Democrats are engaging in "class warfare" when they clamor for higher taxes on the wealthy. A YouTube clip of her remarks has liberals cheering; MoveOn calls it "The Elizabeth Warren Quote Every American Needs To Hear." Warren, who is seeking the Democratic nomination to face Republican Scott Brown in 2012, claims that raising taxes on those who succeed is justified by "the underlying social contract" that made their success possible: Government services gave them a leg up, so they...