Craig Jelinek, the C.E.O. of Costco, agrees. “Paying employees good wages makes good sense for business,” he said earlier this year, calling for a federal minimum-wage increase. (Costco pays a starting wage of $11.50 an hour in all states where it does business.) “We know it’s a lot more profitable in the long term,” Jelinek said, “to minimize employee turnover and maximize employee productivity, commitment and loyalty.” He should know; he started his career as a checkout boy.

There are more pressing reasons for a higher minimum wage, Krueger argues. “It increases the reward for work for people who have struggled in the economy over the past few decades,” he said, ticking off a long list of positive effects it might have: “It helps low-wage workers to raise their family above the poverty line. It has a small ripple effect for people making more than the minimum wage. It particularly helps women.” Ultimately, raising the minimum to, say, $9 an hour might lift hundreds of thousands of families above the poverty line and erase as much as 20 percent of the increase in income inequality that has emerged since the 1980s, according to the Obama administration, which supports legislation that would raise the federal minimum to that very level. (Krueger spent two years as Obama’s chairman of the Council of Economic Advisers.)

Of course, conservatives in Washington, like Speaker John A. Boehner, tend to disagree. “I’ve got 11 brothers and sisters on every rung of the economic ladder,” he told reporters before House Republicans unanimously voted down a proposal to gradually raise the minimum wage to $10 earlier this year. “I know about this issue as much as anybody in this town. What happens when you take away the first couple of rungs on the economic ladder, you make it harder for people to get on the ladder. Our goal is to get people on the ladder.”

But Boehner has a point, at least in theory: If White Castle raises its starting pay to $15 an hour, it purchases access to a better pool of employees, made considerably larger by a high jobless rate. Labor retention has its benefits, but the downside might be less hiring of those whose only option had been the worst jobs. There will still be millions of teenage or otherwise unskilled employees left out of the labor force.

Raising the minimum wage is hardly a panacea. For one, it does little for the millions of struggling families who have higher hourly wages or a salary. Second, the strongest division between those below the poverty line and those just above it is work itself. Raising the minimum wage does little to help the millions of Americans looking for a job.

Messy economics aside, the cynicism of Washington’s political class might ultimately lead to the increase. The minimum wage’s value has eroded over time, and raising it is hugely popular among voters. Corporate profits are well north of a trillion dollars a year. The federal government, meanwhile, continues to run in the red. Unlike any other form of wealth redistribution, raising the minimum wage is basically cost-free to Washington. If it won’t hurt the unemployment rate — as some research suggests — Washington figures, why not slip those fast-food joints the bill?