Is the primary battle between Hillary Clinton and Bernie Sanders more like 2008 or 1980?
In other words, more like the contest between Clinton and Barack Obama, a long, sometimes acrimonious fight that ultimately ended in a unified party winning the presidency?
Or more like the battle between Jimmy Carter and Ted Kennedy, an ideological brawl that dragged on through the convention and eventually saw the incumbent Democratic president defeated?
Democrats need to hope for 2008 and, for now, that race seems the more relevant precedent. Yet they have reasons to fear a 1980 repeat -- and some who lived through that campaign are having unwelcome flashbacks to its length, bitterness and disappointing result.
The argument that 2016 more closely resembles 2008 rests on the important caution that, notwithstanding Thursday's gloves-off debate, hard-fought campaigns tend to get to this level of invective, if not beyond. These wounds always seem gaping at the time; they tend to heal faster than expected.