Causal ontology and definiteness of consciousness

Integrated information theory (IIT) holds that the axioms of phenomenal existence specify both the existence and essential properties of consciousness, whereas the postulates of physical existence describe the conditions a physical substrate of consciousness must satisfy to account for these properties. Among the five axioms and their corresponding postulates, the principle of exclusion has received particular attention. This paper examines the reasoning behind the translation of the exclusion axiom into the exclusion postulate. Section 2 clarifies the exclusion axiom and defends it against common objections. Section 3 explores the broader question of how axioms should be translated into postulates within IIT’s framework. Section 4 outlines the ontological principles underlying the latest formulation of IIT, whereas Sect. 5 focuses on the justification of the second principle, which clarifies how causal powers should be ascribed to physical entities. Drawing on these discussions, the exclusion postulate is then abductively inferred from the exclusion axiom. Section 6 considers potential objections to this inference and assesses their implications.