With fears about the job-killing effects of automation growing every day, once unthinkable ideas are starting to get an airing. A universal basic income (UBI)–where the government gives everyone enough money to live on–has lots of supporters, especially in Silicon Valley. And now some prominent individuals are calling for a tax on robots. The thinking: If you make robots more expensive, there will be more public funds to help retrain workers (or pay for that basic income)–and the higher cost might keep some companies from buying robots and quickly tanking the employment rate.

Bill Gates recently called for a robot tax in an interview with Quartz, arguing that it could slow the shift to a more robot-centric future, allowing society to catch breath. Moreover, he said, it could raise revenues to pay humans for more human types of work, like looking after children or the elderly.