Biden did make a misstep in his counterattack, mislabeling the misrepresented video clip as “doctored,” but that doesn’t mean he’s not still due an abject apology. Instead, however, the Sanders campaign has doubled down. Rather than admitting that it smeared a rival, the campaign is going around claiming that Biden has a long record of trying to cut Social Security. There is, unfortunately, some truth in that claim — but it doesn’t excuse either the original lie or the refusal to admit error.