STARTING around the turn of the millennium, the United States experienced the most alarming change in mortality rates since the AIDS epidemic. This shift was caused, not by some dreadful new disease, but by drugs and alcohol and suicide — and it was concentrated among less-educated, late-middle-aged whites.

We had hints that something like this was happening. We knew suicide was increasing among the middle-aged, that white women without a high school degree were struggling with health issues, that opiate addiction was a plague in working-class communities. But we didn’t know it was all bad enough to send white death rates modestly upward in the richest nation in the world.

Now we know, thanks to a new paper from the Nobel laureate Angus Deaton and his wife, Anne Case. And their findings, inevitably, are the latest ideological Rorschach test in the debate over how to save the American working class.

To many conservatives, the mortality rate shock is the latest indictment of modern liberalism’s mix of moral permissiveness and welfare-state paternalism: The first undercuts the rootedness, discipline and purpose that marriage and religion once supplied, and the latter eases people into a life of dependence and disability payments that only encourages drug abuse and suicidal thoughts.