What the rise of a less liberal, more radical, intransigent, and populist right is forcing progressives to confront is that this way of conceiving of democratic politics is a fiction. Nothing in democratic politics is given — or rather, the things we consider given at any moment enjoy this status for no more exalted reason than that public opinion (expressed primarily through elections) favors treating it as such. But the settlement or consensus in its favor is always temporary and contingent. The contestation of politics, the struggle over power and ideas, over the Constitution and the law and who we are as a political community, never ends. It’s always possible for a settlement or consensus at one moment of history to be rethought, overturned, or reversed. Rights granted can later be rescinded — and there’s no way to prevent that from happening beyond continuing the fight, day after day.
History isn’t an arc slowly bending toward justice. It’s a battlefield on which a skirmish line shifts back and forth in an unending contest between ideological combatants. The agonistic character of politics becomes concealed during eras defined by consensus, when the skirmish line stays in much the same place, shifting only slightly or fairly slowly from year to year and decade to decade. But such eras are the exception in history — or at least never more than a temporary interlude between periods of more rapid or intense struggle.