Two recent events, on opposite sides of the Atlantic, point to the same problem. In Britain, the man widely expected to replace the stately Keir Starmer as prime minister is Andy Burnham, who touts “ business-friendly socialism ” as his credo. In New York, Democratic primary elections produced striking victories for democratic socialists, suggesting that the insurgent left has found a way to turn protest into power. First, a caveat: The left is not marching uniformly toward socialism. Many