At Musk’s 2013 birthday party in Napa Valley, they got into a passionate debate in front of the other guests, including Luke Nosek and Reid Hoffman. Musk argued that unless we built in safeguards, artificial intelligence systems might replace humans, making our species irrelevant or even extinct. Page pushed back. Why would it matter, he asked, if machines someday surpassed humans in intelligence, even consciousness? It would simply be the next stage of evolution.