concept

Integrated Information Theory (IIT)

A theory of consciousness proposed by neuroscientist Giulio Tononi, holding that consciousness is not tied to any particular substrate (meat, carbon, or silicon) but is identical to the amount of *integrated information* a system generates, denoted by the value Φ (phi). For a high Φ, a system must be both highly differentiated (capable of many distinct states) and highly integrated (its information cannot be split into independent parts), which demands fast, irreducible recurrent feedback. Under IIT, a vast feed-forward network - however intelligently it behaves - has a Φ of zero. The theory is fiercely contested, even branded "pseudoscience" for being hard to test, but it remains the most mathematically rigorous attempt to measure consciousness.