Cost is 2.1 trillion dollars and destroys the labor market.

Dr. Hamilton, who favors a federal job guarantee, was co-author of a 2018 study — with Mark Paul, William A. Darity Jr. and Khaing Zaw — that sought to estimate the cost. Based on 2016 employment figures, and assuming an average cost per job of $55,820, including benefits, the study found it would cost $654 billion to $2.1 trillion a year, which would be offset to some extent by higher economic output and tax revenue, and savings on other assistance programs like food stamps and unemployment insurance.

And the prospect of a large-scale government intervention in the labor market raises thorny questions.

First, there’s determining the work the government could offer to fulfill a job guarantee. Health care and infrastructure projects require workers with particular skills, as do high-quality elder care and child care. Jobs, say, in park maintenance or as teaching aides could encroach on what local governments already do.

What’s more, the availability of federal jobs would drastically change the labor equation for low-wage employers like McDonald’s or Walmart. Dr. Strain argues that a universal federal guarantee of a job that paid $15 an hour plus health benefits would “destroy the labor market.”