I think most of you know I’m not a fan of integrated information theory (IIT). However, it is a theory proposed by scientists, and I’ve always had a mildly guilty conscience over not having read about it other than through articles and papers. Some years ago, I tried to read Giuilio Tononi’s book, PHI: A Voyage from the Brain to the Soul, but was repelled by its parable format and low information density, and so never finished it. So when Christof Koch’s new book, The Feeling of Life Itself, was announced, and that it would be an exploration of IIT, I decided I needed to read it.
Koch starts off by defining consciousness as experience, “the feeling of life itself.” He muses that the challenge of defining it this way is that it’s only meaningful to other conscious entities.
He then discusses the properties of experience, properties that eventually end up being axioms of the theory.
- Experience exists for itself, without need for anything external, such as an observer.
- It is structured, that is, it has distinctions, being composed of many internal phenomenal distinctions.
- It’s informative, distinct in the way it is, contains a great deal of detail, and is bound together in certain ways.
- It’s integrated, irreducible to its independent components.
- It’s definite in content and spatiotemporal grain, and is unmistakable.
These then map to postulates of the theory.
- Intrinsic Existence: the set of physical elements must specify a set of “differences that make a difference” to the set itself.
- Composition: since any experience is structured, this structure must be reflected in the mechanisms that compose the system specifying the experience.
- Information: a mechanism contributes to experience only if it specified “differences that make a difference” within the system itself. A system in its current state generates information to the extent that it specifies the state of a system that could be its possible cause in the past and its effect in the future.
- Integrated: the cause-effect structure specified by the system must be unified and irreducible, that is, the system can’t be reduced to independent non-interacting components without losing something essential.
- Exclusion: only the set of elements that is maximally irreducible exists for itself, rather than any of its supersets or subsets.
All of this feeds into the “central identity of IIT”, which I’ll quote directly from the book.
The central identity of IIT, a metaphysical statement, makes a strong ontological claim. Not that Φmax merely correlates with experience. Nor the stronger claim that a maximally irreducible cause-effect structure is a necessary and sufficient condition for any one experience. Rather, IIT asserts that any experience is identical to the irreducible, causal interaction of the interdependent physical mechanism that make up the Whole. It is an identity relationship—every facet of any experience maps completely onto the associated maximally irreducible cause-effect structure with nothing left over on either side.
Koch, Christof. The Feeling of Life Itself (The MIT Press) . The MIT Press. Kindle Edition.
All of this factors into the calculation of Φ (pronounced “phi”), a value which indicates the extent to which a system meets all the postulates. However, as noted in the postulates, there can be Φ values for subsets and supersets of the system. What we’re interested in is Φmax, the combination of elements that produce the maximum amount of Φ. According to the Exclusion postulate, only this particular combination is conscious.
The Exclusion postulate allows IIT to avoid talking about multiple consciousnesses within one brain, or of group consciousnesses. Although it doesn’t rule out scenarios where splitting or combining systems results in new consciousnesses, such as what happens with split-brain patients, or what might happen if two people’s brains were somehow integrated together.
Not all of the brain is necessarily included in its Φmax, but a particular subset. Koch thinks this is a region he calls the posterior cortical hot zone, including regions in the parietal, temporal, and occipital lobes. In essence, it’s the overall sensory cortex, the sensorium, as opposed to the action cortex, or motorium at the front of the brain, which is why that Templeton contest between IIT and global workspace theories (GWT) is focused on whether consciousness is more associated with the back or front of the brain.
Koch discusses the evolution of consciousness. He sees it going back to the reptiles, when the sensory cortex first started to develop. (Somewhere around the rise of reptiles, or mammals and birds, seems to be where most biologists see consciousness arising, excluding fish, amphibians, and most invertebrates, although as always, a lot depends on the definition of consciousnss being considered.)
Koch in his earlier book, Consciousness: Confessions of a Romantic Reductionist, evinced a comfort level with panpsychism. In the disccusion of IIT in that book, he implied that IIT and panpsychism were compatible. But in this book, I got the feeling that he now views IIT more as an alternative to panpsychism, one which resolves some of panpschism’s issues, such as the combination problem.
As noted above, I’m not a fan of IIT, and I can’t say that this book helped much. All the axioms and postulates make it feel more like philosophy than science. It continues to feel very abstract and disconnected from actual neuroscience. Some of the axioms, such as structure and information, seem vague and redundant to me. (The book adds examples, but I didn’t find them to help much.) And others, such as the exclusion principle, seem arbitrary, included to save appearances.
The intrinsic existence one seems to imply metacognitive self awareness, but the theory simply asumes that it emerges somehow from integration, ignoring the actual neuroscience of the regions in the brain associated with introspection. The postulate also ends up attibuting self awareness to all animals going back to reptiles, despite the lack of any empirical support.
IIT also posits that the feeling of all this emerges from the integration, again ignoring all the neuroscience on affects and survival circuits. Bringing in all that neuroscience inescapably leads us to the front of the brain, which Koch rules out as having a role in consciousness.
And Scott Aaronson’s classic takedown of the theory remains in my mind. Koch mentions Aaronson’s criticism, but like Tononi, doubles down and accepts that the arbitrary systems with trivially high Φ that Aaronson envisages are in fact conscious. If the theory’s designations of consciousness aren’t going to match up with our ability to detect it, how scientific is it really?
But I think my biggest issue with IIT is it inherently attempts to explain the ghost in the machine, particularly how it’s generated. Most of the other theories I find plausible simply dismiss the idea of the ghost, I think rightly so. There’s no evidence for a ghost, either spiritual, electromagnetic, or any other variety. The evidence we have is of the brain and how it functions.
I’ll be happy to go back to IIT if it manages to rack up empirical support. Until then, it seems like a dead end.
To be clear, I do think integration is crucial, just not in the specific way IIT envisages it. There are many integration regions in the brain, regions which are themselves integrated with each other. But Antonio Damasio’s convergence-divergence zones and convergence-divergence regions seem to model this in a much more grounded manner than IIT.
What do you think? Am I too skeptical of IIT? Are there virtues of the theory that I’m missing?