In a paper published in March in the journal Science, David Lazer, Matthew Baum and 14 co-authors consider what we do and don’t know about the science of fake news. They define fake news as “fabricated information that mimics news media content in form but not in organizational process or intent,” and they go on to discuss problems at multiple levels: individual, institutional and societal. What do we know about individuals’ exposure to fake news and its influence upon them? How can Internet platforms help limit the dissemination of fake news? And most fundamentally: How can we succeed in creating and perpetuating a culture that values and promotes truth?