What do we lose when social insurance unravels?

It is startling to realize just how much the social safety net expanded during Barack Obama’s presidency. In 2016, means-tested entitlements like Medicaid and food stamps absorbed 3.8 percent of the nation’s gross domestic product, almost a full percentage point more than in 2008.

Public social spending writ large — including health care, pensions, unemployment insurance, poverty alleviation and the like — reached 19.3 percent of G.D.P., the most in decades and almost three percentage points more than in the year before Mr. Obama took office.

Government in the United States still spends less than most of its peers across the industrialized world to support the general welfare of its citizens. But during the Obama administration the gap shrank to its smallest since the early 1980s. By these numbers, American social policy looks closer to that of the social democracies in Europe than at any time in a generation.

It didn’t stick, though.

Last week, President Trump’s sketch of a budget underscored how little interest he has in the nation’s social insurance programs — proposing to shift $54 billion next year to the military from the civilian discretionary budget that funds many of the government’s social efforts.