On the non-uniqueness problem in integrated information theory.

Integrated Information Theory (IIT) 3.0, a leading theory of consciousness, defines a mathematical measure Φ meant to quantify consciousness. This work demonstrates that Φ is not well-defined because its value is non-unique. An algorithm that computes all possible Φ values for a given system, strictly following the theory's definition, reveals that published Φ values are arbitrarily selected from many equally valid alternatives. Crucially, both high and low Φ values can be predicted simultaneously for the same system, making it impossible to decide whether that system is conscious under the current formulation of IIT.

Study at a glance

Abstract

Integrated Information Theory (IIT) 3.0 is among the leading theories of consciousness in contemporary neuroscience. The core of the theory relies on the calculation of a scalar mathematical measure of consciousness, Φ, which is inspired by the phenomenological axioms of the theory. Here, we show that despite its widespread application, Φ is not a well-defined mathematical concept in the sense that the value it specifies is non-unique. To demonstrate this, we introduce an algorithm that calculates all possible Φ values for a given system in strict accordance with the mathematical definition from the theory. We show that, to date, all published Φ values under consideration are selected arbitrarily from a multitude of equally valid alternatives. Crucially, both [Formula: see text] and [Formula: see text] are often predicted simultaneously, rendering any interpretation of these systems as conscious or not, non-decidable in the current formulation of IIT.