The original version of this story appeared in Quanta Magazine.

Science routinely puts forward theories, then batters them with data till only one is left standing. In the fledgling science of consciousness, a dominant theory has yet to emerge. More than 20 are still taken seriously.

It’s not for want of data. Ever since Francis Crick, the codiscoverer of DNA’s double helix, legitimized consciousness as a topic for study more than three decades ago, researchers have used a variety of advanced technologies to probe the brains of test subjects, tracing the signatures of neural activity that could reflect consciousness. The resulting avalanche of data should have flattened at least the flimsier