How a Fervent Belief Split Silicon Valley—and Fueled the Blowup at OpenAI

Over the past few years, the social movement known as effective altruism has divided employees and executives at artificial-intelligence companies across Silicon Valley, pitting believers against nonbelievers.

The blowup at OpenAI showed its influence—and the triumphant return of chief executive Sam Altman revealed hard limits, capping a bruising year for the divisive philosophy.