CONCEPT
The Exclusion Postulate
IIT's axiom that consciousness exists at one particular spatiotemporal grain — the grain at which phi is maximized — and only at that grain, making consciousness ruthlessly singular and drawing the precise borders of the self.
The Exclusion Postulate is IIT's fifth axiom, stating that consciousness exists at exactly one spatiotemporal grain: the grain at which integrated information is maximized. Not coarser, not finer, not multiple grains simultaneously. This follows from the phenomenological observation that every experience has definite borders, specific contents, and a particular grain. The postulate has dramatic consequences: it determines the precise physical substrate of consciousness, rules out nested or overlapping consciousnesses within a single system, and has distinctive implications for distributed AI systems whose natural grain of integration is ambiguous or non-existent.
In The You On AI Field Guide
The exclusion postulate transforms an abstract philosophical question — where is the self located? — into a specific mathematical problem. At any given moment, a physical system admits many possible descriptions: at the level of atoms, molecules, neurons, brain regions, or the whole system. Each level generates a different value of phi. The postulate says that only the level at