The G.I. Bill, passed during World War II, had a similar effect. Veterans who took advantage of education, job training and mortgage assistance under the law felt valued as citizens, and that, subsequently, made them more involved in politics and civic life.

The evidence is not just anecdotal. Two political scientists found, in a study of social programs in developed countries, that public benefit programs that rely more on universally distributing resources enjoy more political sustainability.

On the other hand, offering benefits through more opaque and income-reliant ways tends to dampen these effects. As the political scientist Suzanne Mettler has noted, in a 2008 poll, many people who had received benefits funneled through the tax code, such as the mortgage interest deduction, swore they’d never used a government program. They were therefore less likely to believe that the government had helped them get ahead.

People who receive cash assistance — for which they must prove their poverty and their willingness to work, and in some states, even undergo a drug test — are actually less likely to get involved in politics than those who do not. As the sociologist Jamila Michener has found, similarly punitive policies in Medicaid make people feel disempowered, causing them to withdraw from political participation.

The heavy administrative costs to determine who qualifies for a benefit aren’t just a burden on governments. (States spend millions on drug screening for welfare recipients and rescind checks from those who screen positive.) The beneficiaries bear the administrative cost of repeatedly proving that they make little enough to qualify. Such paperwork often dissuades people from enrolling in programs at all. When Arkansas required low-income residents to report their work hours to stay enrolled in Medicaid, more than 18,000 people lost coverage in a span of seven months.

Universal programs also seem to be more effective at attaining the desired results: lowering poverty and reducing income inequality. Universal preschool programs, for example, improve reading scores for low-income students, while targeted programs do not. Universal child care systems in Quebec and Washington, D.C., have also significantly increased the share of women in the labor force.

The government doesn’t need to make every single benefit universal. But the public goods that are essential to a full and healthy life — health care, education and child care — should be available to all. Some presidential contenders have finally realized the political benefits of designing them this way.

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