What exactly are the dangers posed by AI?

In late March, more than 1,000 technology leaders, researchers and other pundits working in and around artificial intelligence signed an open letter warning that AI technologies present "profound risks to society and humanity."

The group, which included Elon Musk, Tesla's CEO and the owner of Twitter, urged AI labs to halt development of their most powerful systems for six months so that they could better understand the dangers behind the technology.

"Powerful AI systems should be developed only once we are confident that their effects will be positive and their risks will be manageable," the letter said.

The letter, which now has more than 27,000 signatures, was brief. Its language was broad. And some of the names behind the letter seemed to have a conflicting relationship with AI. Musk, for example, is building his own AI startup, and he is one of the primary...