For most of our history, socialism has been a dirty word and an almost un-American concept. But a recent Gallup poll shows that for a majority of 18- to 29-year-olds, socialism is viewed more positively than capitalism. This is a sea change, with candidates like Bernie Sanders and Alexandria Ocasio-Cortez pushing for Medicare for All, subsidized college tuition and a Green New Deal—once fringe ideas now front and center in the Democratic Party.