Each of IIT's five axioms and related postulates make unjustifiable claims about physical reality and about the phenomenology (appearance) of consciousness. They should be understood as assumptions describing a formal system that might be implemented in a digital computer that can simulate his theory of consciousness.

1. INTRINSIC EXISTENCE

   Consciousness exists: each experience is actual—indeed, that my experience here and now exists (it is real) is the only fact I can be sure of immediately and absolutely. [cf. René Descartes's inability to doubt his existence.] Moreover, my experience exists from its own intrinsic perspective, independent of external observers (it is intrinsically real or actual).

   Comments: Consciousness, i.e, the subjective experience of personal private feelings accompanying our thoughts and actions, is the very antithesis of shared, objective, external, scientifically observable events in the physical world that we call "real."
   The frequently confabulated reporting of subjective feelings and thoughts is widely considered to prove that they are in no way "immediately and absolutely" certain "facts."

2. COMPOSITION

   Consciousness is structured: each experience is composed of multiple phenomenological distinctions, elementary or higher-order. For example, within one experience I may distinguish a book, a blue color, a blue book, the left side, a blue book on the left, and so on. being the immaterial arrangement of the physical material that embodies/instantiates the information.

3. INFORMATION

   Consciousness is specific: each experience is the particular way it is—being composed of a specific set of specific phenomenal distinctions—thereby differing from other possible experiences (differentiation). For example, an experience may include phenomenal distinctions specifying a large number of spatial locations, several positive concepts, such as a bedroom (as opposed to no bedroom), a bed (as opposed to no bed), a book (as opposed to no book), a blue color (as opposed to no blue), higher-order “bindings” of first-order distinctions, such as a blue book (as opposed to no blue book), as well as many negative concepts, such as no bird (as opposed to a bird), no bicycle (as opposed to a bicycle), no bush (as opposed to a bush), and so on. Similarly, an experience of pure darkness and silence is the particular way it is—it has the specific quality it has (no bedroom, no bed, no book, no blue, nor any other object, color, sound, thought, and so on). And being that way, it necessarily differs from a large number of alternative experiences I could have had but I am not actually having.

   Comments: An experience, like any material or ideal object, necessarily differs from all other objects. It is the nature of information identity, which, like Tononi, we divide into intrinsic and extrinsic (relational) identity..

4. INTEGRATION

   Consciousness is unified: each experience is irreducible and cannot be subdivided into non-interdependent, disjoint subsets of phenomenal distinctions. Thus, I experience a whole visual scene, not the left side of the visual field independent of the right side (and vice versa).

   Comments: Information structure are "composed" of its components, so in general can be subdivided into independent parts. For example, the visual field on the retina and on the visual cortex is dependent on photons emerging from objects in the external world, which may or may not depend on one another.

5. EXCLUSION

   Consciousness is definite, in content and spatio-temporal grain: each experience has the set of phenomenal distinctions it has, neither less (a subset) nor more (a superset), and it flows at the speed it flows, neither faster nor slower.

   Comments: This is again trivially true of any spatio-temporal object or process. Again, it is the question of identity. Everything is what it is, neither less nor more, and proceeds at its speed, neither faster nor slower.

IIT's corresponding postulates claim that a physical system, if conscious, is so by virtue of its causal properties. A "physical system" is taken to be a set of elements, each with two or more internal states, inputs that influence that state, and outputs that are influenced by that state (neurons or logic gates are the natural examples).

Comments: Nature is non-causal or acausal at the quantum level, and only statistically or "adequately" deterministic at the macroscopic level.

Before I come to the mathematical innards of the theory, let me address one general objection to IIT that I frequently encounter. It runs along the following lines. Even if everything about IIT is correct, why should it feel like anything to have a maximum of integrated information? Why should a system that instantiates the five essential properties of consciousness— intrinsic existence, composition, information, integration, and exclusion— form a conscious experience? IIT might correctly describe aspects of systems that support consciousness. But, at least in principle, skeptics might be able to imagine a system that has all these properties but which still doesn't feel­ing like anything. [For example, David Chalmers' "zombies."]

I answer this conceivability argument in the following manner. By con­struction, these five properties fully delimit any experience. Nothing else is left out. What people mean by subjective feelings is precisely described by these five axioms. Any additional "feeling" axiom is superfluous. Is there a mathematically unassailable proof that satisfying those five axioms is equivalent to feeling like something? Not to my knowledge. But I'm a sci­entist, concerned with the universe I find myself in, and not with logical necessity. And in this universe, so I argue in this book, any system that obeys these five axioms is conscious.

The Feeling of Life Itself.pp.76-77.

according to IIT (i) what actually exists is an entire cause-effect structure, much more than the first-order cause-effect repertoires of atomic elements; (ii) when a conceptual structure changes much more happens than first-order events; and (iii) its changes are caused by much more than first-order causation. This view, together with the central identity of IIT, which says that an experience is a conceptual structure that is maximally irreducible intrinsically, has several implications for the notions of free will and responsibility (Tononi 2013).

First, for a choice to be conscious, a system’s cause-effect power must be exerted intrinsically - upon itself: the conceptual structure must be “causa sui.” In other words, a conscious choice must be caused by mechanisms intrinsic to a complex rather that by extrinsic factors. This requirement is in line with the established notion that, to be free, a choice must be autonomous - decided from within and not imposed from without.

Second, for a choice to be highly conscious, the conceptual structures that correspond to the experience of deliberating and deciding (“willing”) must be highly irreducible - they must be composed of many concepts, including a large number of higher-order ones. In other words, a conscious choice involves a large amount of cause-effect power and is definitely not reducible to first-order causes and effects. Hence, the reductionist assumption that ultimately “my neurons made me do it” is just as definitely incorrect.

Seen this way, a system that only exists extrinsically, such as a feed-forward network, is not “free” at all,, but at the mercy of external inputs. In this case nothing exists from the intrinsic perspective - there is nothing it is like to be a feed-forward network. But if intrinsically there is nothing, it cannot cause anything either. There is only extrinsic causation - a machine “going through the motions” for the benefit of an external manipulator/observer. On the other hand, a system that exists intrinsically, but only minimally so - say two coupled elements that can only turn on and off together, achieving minimal values of Φ, may well be free, but it has minimal “will.” In other words, while its choices are free because they are determined intrinsically, very little is being determined - just two first-order concepts. By contrast, a complex that specifies a rich conceptual structure of high Φ is both free and has high will: its choices are determined intrinsically and they involve a large amount of cause-effect power. That is to say, to have free will, one needs to be as free as possible from external causes, and as determined as possible by internal causes - the multitude of concepts that compose an experience. In short, more consciousness, more free will.

The claim that the more one’s choices are intrinsically determined, the more one has free will, may at first seem at odds with the widespread conviction that determinism and free will are incompatible. However, at issue is not determinism, but the combination of the extrinsic perspective and reductionism. Consider again the role of our neurons when we make a decision. The extrinsic perspective applied to neurons shows us that what each neuron does is determined extrinsically, by its inputs; hence neurons are not free, just like transistors are not. Moreover, ontological reductionism leads us to believe that ultimately all there is are neurons; hence none of us, being constituted of neurons, is free, just like a digital computer is not free. In this scenario, consciousness and conscious decisions are inevitably epiphenomenal: they merely “go along for the ride” but have no causal role to play, as the neurons do all the causal work (ref). If we look at the brain this way, it does not seem to be fundamentally different from any other machine, say a digital computer running a simulation, except that the elements that update their state are neurons rather than transistors. In both cases, we envision a machine “going through its motions”, which leaves no room for free will. As was argued above, however, there is much more to the neural substrate of consciousness than just neurons and their extrinsic determinants: if we adhere to maximally irreducible cause-effect power as the criterion for existence, what exists when we make a conscious choice is a rich conceptual structure, involving much more than first-order causation by individual neurons. Moreover, the cause-effect power is exerted intrinsically, rather than extrinsically: it is not the extrinsic inputs to each neurons that make things happen, but the conceptual structure acting upon itself. In summary, when I deliberate and make a decision, what exists and causes the decision is my own consciousness – nothing less and nothing more, and the decision is free because it has been brought about by intrinsic causes and effects. By contrast, when a digital simulation of my neurons unfolds, even if it leads to the same behavior, what exists are just individual transistors, whose individual choices are determined extrinsically: there is no consciousness, no intrinsic causation, and therefore no free will.

Finally, it is often suggested that one’s will can be free only if one might have acted otherwise – the so-called requirement for alternative possibilities. But according to IIT, determinism is the friend, not the foe of free will, since any indeterminism reduces cause-effect power and therefore reduces free will. Said otherwise, if I were to find myself in the same exact situation, I would want to choose in exactly the same way, since in this way the choice would not be left to chance, but would be fully determined by me - a “me” that includes the full richness of my consciousness – my understanding, my memories, and my values.

Scholarpedia article, Integrated Information Theory

We see that Tononi, like his close colleagues Gerald Edelman, Christof Koch, and Daniel Dennett, is a compatibilist. He is also a reductionist and determinist.

He accepts the standard argument against free will. We are not free to do otherwise in the "exact same situation." There are no alternative possibilities.

Wikipedia on IIT

Scholarpedia on IIT