Roy Moore, in this sense, was Trump’s Trump — the man who took this mode of politics to 11 and beyond. The president has harassment accusations; the judge had mall-trawling accusations. Trump is a race-baiter; Moore was a stock character from a message movie about Southern bigotry. Trump’s populism mixed reasonable grievances in together with some stupid ones; Moore’s populism was the purest ressentiment. And like Trump but much, much more so, the Moore campaign relied on the assumption that Republicans who didn’t care for who he was and what he represented simply had nowhere else to go.

So while Moore’s defeat is, yes, specific to him, specific to the statutory rape accusations and all the rest of his problems as a candidate, it’s also a pretty clear foretaste of what you get when you distill white identity politics to a nasty essence and then try to build a coalition around it. You get massive Democratic turnout, black turnout in particular, slumping Republican turnout, and a whole lot of write-in votes from people who should be your supporters. You get Democrats winning elections in the most unlikely places. And you get, quite probably, a Democratic majority in the House and perhaps even the Senate.

Is that future inevitable? In theory, no. When Scott Brown won in Massachusetts, it was possible to imagine the Obama White House learning something from the defeat, course-correcting on health care, passing a more modest bill, dialing back their ambitions, making a public show of being chastened. They did not do so, in the end, but they certainly considered it, with Rahm Emanuel in particular championing that course — one that might, might, have saved some Democratic House and Senate seats in the Republican wave of 2010.

So just as the Obama people considered course correcting after Coakley’s loss, you could theoretically imagine the Trump people course correcting after Moore’s — inducing the president to abandon his online feuds and insults, weaving a little more racial sensitivity into his rhetoric and actions, even persuading the G.O.P. leadership to rewrite its tax bill to make it a little less howlingly unpopular. Moreover such a pivot would be easier politically, in a sense, with Roy Moore defeated rather than narrowly elected, since he won’t be in the Senate and thus in every Democratic 2018 ad, tainting the Trump White House by association every day.

But who are we kidding? The Obama White House considered a course correction because for all its flaws it was a rational and functional place, capable of doing cost-benefit analyses and changing strategies as the political situation altered. And team Obama decided to stay the course for what were debatable but also rational reasons — the theory that a sweeping health care bill would be simply worth the political pain and midterm election losses required to get it passed.