One morning in December 2024, Mikole Weeks, then 35, received a phone call with surprising news. She had been chosen for an experimental program called guaranteed basic income, and it came with cash: $1,330 a month for an entire year, with no strings attached for how it could be spent.

“It felt like another chance to turn my life around,” said Ms. Weeks, a single mother and a part-time house cleaner in Santa Cruz, Calif.

Only it did not turn out to be quite that simple.

For decades, people have debated the merits of guaranteed income programs, also called universal basic income, as an alternative or complement to traditional welfare. Driving the efforts is the idea that the most effective way to improve people’s lives is to give them cash and let them spend it how they want.

The concept resurged in popularity a decade ago, driven by fears of automation and rising wealth inequality. Proponents argued that permanent payments would raise the standard of living for those on the margins, and ultimately lift millions off welfare. Critics contended that giving people money unconditionally would deter them from working in the first place.

In the age of artificial intelligence, these programs have again become a hot topic. Tech titans including Elon Musk, Sam Altman of OpenAI and Dario Amodei of Anthropic have hailed basic income as a solution to A.I.-fueled job losses. In April, Mr. Musk posted that “universal HIGH INCOME” was the best way to deal with unemployment caused by the powerful technology. In June, Dr. Amodei suggested a tax on A.I. companies as one way to fund these payments.

Across Silicon Valley, experimental guaranteed income programs have quietly taken off. Google began funding six different initiatives in 2022 as part of a $50 million donation to nonprofits in the San Francisco Bay Area, saying basic income could be a novel way to prevent homelessness in one of the nation’s most expensive locations. Each program has hundreds of participants who receive around $1,000 a month, and academics study the results. State and federal tax laws limit the lengths of the programs and the payment amounts.