New Delhi, Sept. 17 -- FEW EVENTS have brought together Bernie Sanders and Steve Bannon, political firebrands from opposite ends of the spectrum, in common cause. But the Pro-Human Assembly in Washington, DC on September 15th, a gathering of people alarmed by the rapid advance of artificial intelligence, managed it. Both men warned of the unchecked power of tech "oligarchs" and called for urgent legislation to slow down the technology.

Donald Trump, the president, is unmoved by the torrent of such demands. AI's supposed risks to humanity, he wrote on social media, were a "hoax". America's aim was to beat China; proponents of a slowdown were "treasonists". But in recent days, political momentum for tighter controls has gathered with unusu...