Finally, there is policy. Democrats have indeed moved somewhat to the left over the last few decades, on both social and economic issues. As Lawrence Summers, the former Treasury secretary (and no lefty revolutionary), likes to say, the last 15 years should have nudged open-minded people to the political left: The free market isn’t delivering healthy increases in living standards for most Americans. In response, Democrats are focusing less on Bill Clinton’s old themes, like personal and fiscal responsibility, and more on using the government to help people.

But think about what a truly left-wing agenda would look like: Top tax rates of 70 percent (which we had as recently as 1980) or higher. A generous “universal basic income.” The elimination of employer-provided health insurance, with a system more like Britain’s. These ideas remain limited to the margins. None is likely to happen even if Democrats sweep the elections of 2020.