The trouble went deeper than the specters of terrorism and far-right extremism, however. Silicon Valley was beginning to awaken to another, more fundamental challenge. This was a growing realization that all the doomsaying about homophily, filter bubbles, and echo chambers had been accurate. In crucial ways, virality did shape reality. And a handful of tech CEOs stood at the controls of this reality-shaping machine—but they hadn’t been working those controls properly.

