As the years passed, Chalmers and Koch forgot about their bet, but in 2018, the science journalist Per Snaprud brought it back to their attention. A few years later, as part of a $20 million project supported by the Templeton World Charity Foundation, a series of “adversarial experiments” were designed to pit theories of consciousness against each other, including global workspace theory (GWT) and integrated information theory (IIT).

GWT imagines consciousness as a theater: The brain is populated by a crowd of local information streams, but only what gets broadcast to the whole crowd — put onstage — becomes conscious. IIT identifies consciousness with the degree of, yes, integrated information, represented by the Greek character phi (Φ). The more phi, the more consciousness.