Guilio Tononi has proposed a theory of consciousness he calls “Integrated Information Theory” (IIT)*. Very roughly, the theory is based on Shannon’s concept of information, but extends this by adding a property refers to as “Integrated Information”. Consciousness
Information will exist in an entity when it has information and is connected. This property is called “Phi” (rhymes with “by”, written φ) and can be computed. The higher the Phi, the more conscious the entity.
Although theories of consciousness are not new, this one is special: it has high-profile converts, perhaps the most noteable being Christof Koch. Koch, Cal Tech professor and chief scientific officer of the Allen Brain Institute, is best known for his book, The Quest for Consciousness: a Neurobiological Approach. A new Koch book, Consciousness: Confessions of a Romantic Reductionist is largely a description of and paean to IIT. It’s fair to view Tononi and Koch as collaborators.
John Searle is an eminent philosopher who thinks about the brain and is taken seriously by Neuroscientists. Until recently he and Koch were on the same page. For example, Searle has endorsed Koch’s concept of studying the Neural Correlates of Consciousness (NCC). Searle frequently writes for the New York Review of Books, and has on occasion generated debate. Notable was Searle’s 1995 critical review of Daniel Dennett “Consciousness Explained” that generated a prolonged exchange.
In the January 10, 2013 issue of the New York Review of Books Searle reviews “Confessions” and solidifies his disputative reputation**. The review is devastatingly critical. The essence of Searle’s criticism is that IIT employs a mindful observer to explain mind. There is a little man in the middle of the theory; that information isn’t information until it is “read” by an entity with a mind. There may be message in the information carrier, but it becomes information when read.***
The story doesn’t end there. The March 7 issue of the New York Review of Books contains an exchange of letters between Koch-Tononi and Searle (not behind paywall).
My read: I thought the original Searle article was clear and powerful. I’ve read both Tononi and Koch and never quite gotten IIT. I found the Tononi/Koch letter a muddle, and Searle’s reply clear. Since I don’t really get IIT, I don’t want to take sides. Opinions are welcome in the comments section. It will be interesting to see how this plays out.
Update March 18. Panpsychism is a battleground in the Koch/Tononi letter and Searle’s response. According to wikipedia, which seems an adequate source here,
In philosophy, panpsychism is the view that all matter has a mental aspect, or, alternatively, all objects have a unified center of experience or point of view. Baruch Spinoza, Gottfried Leibniz, Gustav Theodor Fechner, Friedrich Paulsen, Ernst Haeckel, Charles Strong, and partially William James are considered panpsychists.
My take: both get hits. Searle doesn’t acknowledge the “local” panpyschism of IIT. IIT has a spatially restricted, spatially centered panpsychism, according to Tononi and Koch in their response letter. That’s why my consciousness doesn’t mix with yours. If a theory of consciousness uses panpsychism, especially a special form, isn’t it assuming the very hard part, asking for special help from novel laws of physics?
Update 2 march 19 A few hours ago I re-read chapter 8 of Koch’s “Confessions”, which contains the entirety of Koch’s description of IIT. I also reread Searle’s review of “Confessions”, and the NYRB letter exchange. In Chapter 8 I searched for a clear description of “connectedness” but couldn’t find it. I don’t know if connectedness is statistical or involves causality. I also looked for an indication that IIT’s panpsychism is localized — that it is centered around a local maxima — but couldn’t find it. My conclusion is that the Koch book is, at best, a remarkably incomplete description of IIT. (and the Koch book is what Searle reviewed.) IIT depends heavily on connectedness; to evaluate IIT we must know what what connectedness means and how a system could detect its own localized connectedness without an external observer. Perhaps readers could direct us to answers.
Update 3 Jan 1, 2014. Christof Koch describes panpsychism in a Scientific American: Is Consciousness Universal?. Refers, nicely, to Searle.
Update 4 March 27, 2014 (much later). I remain skeptical. I’d like to raise a new topic that hasn’t been discussed here: what makes a connection? Clearly, IIT requires connections. What are they? If Neuron A has an axon that synapses on Neuron B, why are thy connected in the IIT world? How does Neuron B know that Neuron A contributed to its activation? Is it simply correlated firing? Is it correlated firing within a certain distance? Is the axon, perhaps microtubules within the axons, part of the connection system? If we can have a physical hypothesis of what a connection is, there would be a mechanism to test, rather than a quantitative description of “size” of consciousness.
* Tononi has a book “Phi: a voyage from the Brain to the Soul“. It’s not a traditional scientific explanation of Phi, but an important resource. Seems intended to deliver the feeling, rather than bedrock substance of Phi.
**Can Information Theory Explain Consciousness? Most of the review is behind a paywall. Contact me (email@example.com). Zenio permits me to send out the text of the paper, one email at a time. March 2014; or download here.
*** Colin McGinn makes this argument eloquently in a more recent article in the NYRB, Homunculism which is a review of Kurzweil’s current book. This is not behind a paywall.