PERSON
Giulio Tononi
The neuroscientist who gave consciousness a number—phi, the measure of integrated information—and in doing so produced the most consequential verdict on the AI age: that the systems reshaping civilization are, in the most precise technical sense, dark inside.
Giulio Tononi began his career mapping the neural dynamics of sleep and waking alongside the Nobel laureate Gerald Edelman, and from that empirical grounding he developed a question that has consumed him since: not what the brain does when it produces consciousness, but what a physical system must
be in order to be identical to consciousness. The result is Integrated Information Theory, or IIT—the most mathematically ambitious attempt in the history of science to transform the hard problem of consciousness from an unsolvable philosophical riddle into a tractable empirical question. IIT begins not with mechanism but with phenomenology: starting from five axioms derivable from introspection alone (experience exists; it is structured; it is specific; it is unified; it is definite), Tononi derives the structural properties any physical system must possess in order to be conscious. Central among them is
phi—the mathematical quantity that measures how much information a system generates as a whole above and beyond the