In one of those rare moments in primary-election politics that seem to genuinely astonish just about everyone not in the challenger's immediate orbit, Alexandria Ocasio-Cortez defeated ten-term incumbent Joe Crowley on Wednesday for the right to become the Democratic nominee to represent New York's 14th district in Congress. Barring disaster, the 28-year-old Bronx native, who was making craft cocktails in Manhattan as recently as last year—and who has never before held public office—will head to Washington in January. Crowley will begin his career as a well-compensated "government-relations specialist" a bit earlier than he expected.

Even Ocasio-Cortez was floored when she saw the results.

As congratulations poured in and Ocasio-Cortez's nascent Wikipedia page expanded in rapid fashion, the search for an explanation began in earnest: How could a young Democratic Socialist who spent about one-tenth as much money as her opponent have bested the man widely assumed to become the next Democratic leader in the House?

The answer is as boring as it is important: Ocasio-Cortez's radical socialist ideas aren't radical anymore. They're practical and popular, and she never apologized for any of them. She favors Medicare for all, and sentencing reform, and the abolition of ICE. She believes housing is a human right and endorses a federal jobs guarantee. She wants Congress to cancel all outstanding higher-education loan balances in order to, as she puts it on her campaign website, "liberate generations of Americans trapped in student loan debt" who are currently barred from meaningful participation in the American economy.

Even during the last election cycle, this brand of progressivism was often dismissed in Democratic circles as silly bumper-sticker fodder, the type of thing favored only by bright-eyed sociology majors who have yet to graduate from college, get a job, take out a mortgage, and otherwise discover How Things Really Work. The party has always been one that favors reasonableness and compromise above all else. Disciplined centrism, said the conventional wisdom, is how Democrats will go about Dr. King's task of bending the arc of the moral universe toward justice.

But two years of a Republican administration hell-bent on making life demonstrably worse for poor people, brown people, and anyone not in Scott Pruitt's immediate family have exposed the weaknesses of that approach, which insists on searching for common ground with opponents who have no interest in finding it. Suddenly, what was viewed as precious and naïve is seen for what it is: a common-sense response to real-life government policies that have been enacted to destroy lives and livelihoods. Thanks to Trump and company, "radical" socialism has become much more mainstream in the Democratic Party than its elders might believe.