His 2014 book Superintelligence was an early examination of AI’s existential risk. One memorable thought experiment: An AI tasked with making paper clips winds up destroying humanity because all those resource-needy people are an impediment to paper clip production.
Good thing we have this philosopher to have the most superficial thoughts about AI while he poops. His second book now seems to be along the lines of "guys, AI will fix everything". What a great follow up to AI will destroy everything. Top twist.