The 2008 Democratic primary contest remains the ugliest the party has experienced for quite some time. If you could somehow travel back in time to primary season exactly twelve years ago you’d find Hillary Clinton and Barack Obama trading in deeply personal insults, torqued opposition research, and throwing anything and everything at each other in the hope that something would stick. It was a contest in which Obama openly derided Clinton as an “out of touch” insider who had “taken more money from lobbyists . . . than any other candidate, Democratic or Republican” in his stump speech. Clinton’s campaign and its partisans would respond in kind by suggesting many of Obama’s supporters were motivated by misogyny and, in justifying her refusal to withdraw from a race she could no longer win Clinton herself would infamously suggest that her opponent might be assassinated like Bobby Kennedy.

Some of us on the Left occasionally wonder how Democrats forget all this, preferring instead to retcon 2016’s comparatively civil contest between Clinton and Bernie Sanders as the moment cherished notions of etiquette and party unity fell apart. But the explanation, at least in retrospect, is actually a fairly straightforward one. Its toxicity notwithstanding, the divide between Clinton and Obama had much less to do with ideology than with two rival personalities and their supporters duking it out. Sure, Obama was an outsider challenging the heir apparent. Sure, he had a gift for soaring oratory and an epochal (though decidedly vague) narrative of change that set him apart from his more traditional establishment opponent. But since his politics were ultimately legible to those in the upper echelons of the Democratic Party and the liberal media, the whole episode was hastily forgotten.

2016 upset this dynamic by throwing ideology into the mix — and, unlike in 2008, the chasm that was opened has never really been closed.