Giulio Tononi’s theory of ‘Integrated Information’ has been said by Christof Koch to be ‘the only really promising fundamental theory of consciousness’. Tononi’s 2012 book ‘Phi: A Voyage from the Brain to the Soul’ provides a popular introduction to it.
Below is an overview of that book rather than a review. Most chapters in the book explicitly provide a summary sentence (‘chapter x, in which y’) and here I am just repeating these, expanding on them slightly and providing a few parenthetical notes as well. If you are after reviews, here are some options…:
- ‘Minds and Brains’ blog review (Gary Williams)
- ‘Three Pound Brain’ blog review (Scott Bakker)
- New Scientist review
- Scientific American review
- New York Times review
- Response to a talk by Tononi
The book is divided into 3 parts, entitled ‘Evidence’ (chapters 2 to 11), ‘Theory’ (chapters 12 to 21) and ‘Implications’ (chapters 22 to 31) through which Galileo is in turn guided by Francis Crick, Alan Turing and Charles Darwin respectively. In so doing, the book mimics the three parts of Dante’s ‘Divine Comedy’ (‘Inferno’, ‘Purgatorio’ and ‘Paradiso’ – ‘Hell’, ‘Purgatory’, and ‘Heaven’, with Dante guided by Virgil and Beatrice). It is even presented as a classic mediaeval text with extensive critical notes at the end of each chapter to allow Tononi to present points in a more direct, less dramatic fashion.
Here’s the overview, chapter by chapter. Italics are the summary of the chapter in the book’s contents page:
- How does consciousness spring out of the matter of the brain?
- Crick: ‘You are nothing but a pack of neurons’. T. H. Huxley: ‘How is it that anything so remarkable as consciousness comes about as a result of irritating nervous tissue, is just about as unaccountable as the appearance of the Djin, when Aladdin rubbed his lamp’.
- The corticothalamic system generates consciousness. Vegetative patients (e.g. Copernicus) continue to breathe but there is little cerebral activity. (‘What if your science, too, is just the image of a need – the need that things are clear and solid and can all be explained? What if your science, too, is just another kind of church…?’.)
- The cerebellum has more neurons than the cerebrum but does not generate consciousness. Contrasting the cerebrum (‘a great bustling metropolis’) with the cerebellum (‘an immense, silent prison’). The cerebellum can be destroyed yet the person survives, though with motor impairment (the cerebellum keeps track of our movements much faster than the cerebrum). Neural systems in the cerebrum learn to predict what remains constant; the higher one goes, the more invariant to irrelevant change the neuronal responses become; they force categories back onto the world, to predict what it might be like (p. 46).
- Sensory inputs are not necessary for consciousness. Contrasting the retinally-blind with the rarer cortically-blind (a form of anosognosia). Vision is in the mind, not in the eye. Those that have become (retinally) blind can still recall images. The cortically-blind have lost the knowledge of what seeing means.
- Motor outputs are not necessary for consciousness. One can be conscious even when completely paralyzed e.g. locked-in syndrome. Contrast this with a machine (e.g. the ‘Automated Confessor’) that may function perfectly but presumably has no soul.
- Many brain circuits that help us see, hear, remember, speak and act are not necessary for consciousness. Example: a damaged hippocampus affects memories but does not seem to affect consciousness.
- Consciousness is divided if the brain is split. The Wada test: observing behaviour when anaesthetizing one then the other cerebral hemisphere. Hemispherectomies and Gazzaniga’s commissurotomy experiments.
- Consciousness can split if different regions of the brain refuse to communicate with each other. Blindsight. Are unconscious perceptions and actions trule unconscious ‘zombie systems’ or are they conscious on their own?
- Consciousness fades when neurons fire strongly and synchronously, as during seizures. (Paracelsus inducing seizures with camphor oil. Possibly the first cognitive activation experiment ever?: Angelo Mosso’s correlations between mental activity and a pulsating soft spot in the patient’s skull.)
- Consciousness fades when cortical neurons can be on and off together, as during dreamless sleep. There is no conscious during deep sleep when neurons are firing synchronously , unlike during wakefulness or REM sleep. (Descartes’s dreams.)
- Consciousness is an enigma. Even if we know fully how the brain (Sherrington’s ‘enchanted loom’) functions physically this will not explain why there is consciousness.
- The humble photodiode can discriminate between light and dark as well as a human. Why are we so sure that it does not experience consciousness, in its own small way?
- Unlike us, the photodiode can still only signal light or dark when presented with a blue light source. We have a huge repertoire to distinguish between. Claude Shannon’s entropy S = Σ p log2 p. Information as the reduction of uncertainty.
- The sensor of a digital camera may have a repertoire of states perhaps larger than a human’s. So information is not the same as consciousness. An observer makes a unity of what is seen whereas the camera is instead a million separate entities of 1 bit each. Kant’s ‘synthetic unity of consciousness’. (Hyeronimus Cardanus is one of the first to put forth a panpsychist view – as was Giordano Bruno).
- Consciousness lives where information is integrated by a single unity above and beyond its parts. There is nothing ‘it is like to be’ two humans observing the same thing without interaction. There is nothing it is like to be a camera sensor. There is no difference if the camera sensor is split into two. Integrated Information, ‘Φ’, is the information generated by a system above its parts. Consciousness is like an onion – layered (hierarchical). Consciousness is the core – the maximum ‘Φ’ – higher that at a higher level e.g two people talking. (Aristotle: ‘The whole is greater than the sum of its parts’. William James: Integration was a key to consciousness.)
- The quality of experience cannot be derived from matter. Thomas Nagel’s ‘What Is It Like to be a Bat?’ There may be a special relationship between certain areas of the brain and certain qualities of our experience. [Synaesthesia?] Oliver Sacks: painter lost perception of colour – achromatopsia.
- Darkness does not exist in a void but requires context. Cells firing in the retina do not contribute to experience. Cutting off connections within the cerebrum, experience of dark would decrease – e.g. would no longer know that dark lacked colour.
- Darkness is built of many nested mechanisms that specify what it is not. Leibnitz (a panpsychist): worms in our belly do not think that we feel anything. The photodiode might be a sensor for temperature rather than light – it has not way of knowing whether it is discriminating light vs dark or hot vs cold. Meaning from mechanism. Pile mechanisms on top of one another and side by side. Problem of panpsychism: how some things have more consciousness than others.
- An experience is a ‘shape’ made of integrated information. Spinoza: a ‘palace of light’ metaphor for a quale as a trillion-dimension probability distribution – a particular experience (quale) has a particular shape in this hyperspace. This, the key chapter, is the least satisfactory – possibly because it is trying to avoid technical details because of the audience it is aimed at. I agree with the end-notes of the chapter: ‘the chapter fails to convey a straightforward message that everybody can understand’ and ‘why resort to such an elaborate, unintelligible metaphor..?’.
- The universe is mostly dark but the largest stars are closer than one thinks if they are looked at with the proper instrument. Under the ‘qualiascope’ a moth was larger than a star.
- ‘Sparks and Flames’. A flame is all we are.
- If consciousness is integrated information, it dissolves with death. Martyrdom of Giordano Bruno. Brain-dead people; heart beating.
- Consciousness disintegrates with dementia.
- If consciousness is a ‘shape’ made of integrated information, it is the only real Hell. Can pain be made to last forever? – by stimulating the brain rather than the body cf. Damasio: pain is in the body. (‘Every steed has lice, and every artist has patrons’!)
- Consciousness can be present in the absence of language and reflection. One can be conscious without being self-conscious (back of brain is active but frontal lobes are not).
- Animals are consciousness too. The joy of a pit pony when brought up to the surface. Damasio’s ‘primitive sense of self’ applies to other animals; the ‘reflective self’ that may be unique to humans is not a necessary condition.
- Consciousness must be present to some degree even before birth. The slippery slope and abortion. ‘One may soon be able to grow our twin from each hair, so every shave is a potential holocaust of millions of your closest brothers’! ‘Respect does not arise in things themselves, but in the thinking burden of our responsibility.’ A foetus will have some ‘Φ’, albeit little. What should guide our conduct: the law, morals or science?
- By investigating nature, new qualia are discovered. Proust vs Shackleton: life relived in memory vs the exploring the world. Freud: whether looking inwards or outwards – both are looking for a way out, from fear of the real. Summary: the routes to discovery are many. Emily Dickinson: They have meaning if they make a difference within one’s consciousness. Brain-in-a-vat experiments (‘City of Lost Children’ film).
- Art and imagination invent new ‘shapes’ within the mind. Borges’s library. The contest between Science and Engineering. Engineering is variation on a theme: reality is the theme and science the rules. For art, the internal shapes (qualia) are more important than the external.
- By growing consciousness, the universe becomes more into being – the synthesis of one and many. Consciousness is a truer form of being. Do the laws of physics exist before they are discovered? The more we learn, the more we bring under consciousness. The more your choices are determined, the more you are free and responsible for them! Knowing is insignificant compared with understanding. Information and causation are the same. I am the synthesis of categorization and association. [Idealism]
- Three late dreams:
- Beethoven: choice between being deaf or having no feeling of anything? All meaning comes from consciousness (but meaning remains cold if it cannot be shared).
- Zeno – nobody is ever the same person twice. Make 2 perfect copies and destroy the original?
- Galileo – do not crave for immortality for myself but for the things I wish to understand.
I had hoped that the book would be introducing the substance of the theory of ‘Φ’ in an accessible way, as found in, for example: