Just in case you are not aware Hakwan Lau has started a blog, In Consciousness we Trust, where he is blogging his work on his upcoming book on consciousness. He has lately been taking fire at the Integrated Information Theory of Consciousness and has a nice (I think updated) version of his talk (mentioned previously here) in his post How to make IIT (and other Theories of Consciousness) Respectable. I have some small quibbles with some of what he says but overall we agree on a lot (surprised? 😉 At any rate I was led to this paper by Sasai, Boly, Menson, and Tononi arguing that they have achieved a “functional split brain” in an intact subject. This is very interesting, and I enjoyed the paper a lot but right at the beginning it has this troublesome set of sentences:
A remarkable finding in neuroscience is that after the two cerebral hemispheres are disconnected to reduce epileptic seizures through the surgical sectioning of around 200 million connections, patients continue to behave in a largely normal manner (1). Just as remarkably, subsequent experiments have shown that after the split-brain operation, two separate streams of consciousness coexist within a single brain, one per hemisphere (2, 3). For example, in many such studies, each hemisphere can successfully perform various cognitive tasks, including binary decisions (4) or visual attentional search (5), independent of the other, as well as report on what it experiences. Intriguingly, anatomical split brains can even perform better than controls in some dual-task conditions (6, 7).
Really?!?! Experiments have shown this? I was surprised to read such a bold statement of a rather questionable assumption. In the first place I think it is important to note that these patients do not verbally report on what it ‘experiences’. I have argued that these kinds of (anatomical) spit brains may have just one stream of consciousness (associated with the one capable of verbally reporting) and that the other ‘mute’ hemisphere is processing information non-consciousnesly.
This is one of the problems that I personally have with the approach that IIT takes. They start with ‘axioms’ which are really (question begging) assumptions about the way that consciousness is, and they tout his as a major advance in consciousness research because it takes the Hard Problem seriously. But does it? As they put it,
The reason why some neural mechanisms, but not others, should be associated with consciousness has been called ‘the hard problem’ because it seems to defy the possibility of a scientific explanation. In this Opinion article, we provide an overview of the integrated information theory (IIT) of consciousness, which has been developed over the past few years. IIT addresses the hard problem in a new way. It does not start from the brain and ask how it could give rise to experience; instead, it starts from the essential phenomenal properties of experience, or axioms, and infers postulates about the characteristics that are required of its physical substrate.
But this inversion doesn’t serve to address the Hard Problem, (by the way, I agree with the way the formulate it for the most part). I agree that the Hard Problem is one of trying to explain why a given neural activation is associated with a certain conscious experience rather than another one, or none at all. And I even agree that in order to address this problem we need a theory of what consciousness is but IIT isn’t that kind of theory. And this is because of the ‘fundamental identity claim’ of IIT that an experience is identical to a conceptual structure, where ‘experience’ means phenomenally conscious experience and ‘conceptual structure’ is a technical term of Integrated Information Theory.
This is a postulated identity, and they do want to try to test it, but even if it was successfully confirmed would it really offer us an explanation of why the experiences are associated with a particular brain activity? To see that the answer is no consider their own example from Figure 1 of their paper and what they say about it. 
They begin,
The true physical substrate of the depicted experience (seeing one’s hands on the piano) and the associated conceptual structure are highly complex. To allow a complete analysis of conceptual structures, the physical substrate illustrated here was chosen to be extremely simple1,2: four logic gates (labelled A, B, C and D, where A is a Majority (MAJ) gate, B is an OR gate, and C and D are AND gates; the straight arrows indicate connections among the logic gates, the curved arrows indicate self-connections) are shown in a particular state (ON or OFF).
So far so good. We have a simplified cause-effect structure in order to make the claim clear.
The analysis of this system, performed according to the postulates of IIT, identifies a conceptual structure supported by a complex constituted of the elements A, B and C in their current ON states. The borders of the complex, which include elements A, B, and C but exclude element D, are indicated by the green circle. According to IIT, such a complex would be a physical substrate of consciousness
So, when A=B=C=1 (i.e. on) in this system it is having a conscious experience (!), as they say,
The fundamental identity postulated by IIT claims that the set of concepts and their relations that compose the conceptual structure are identical to the quality of the experience. This is how the experience feels — what it is like to be the complex ABC in its current state 111. The intrinsic irreducibility of the entire conceptual structure (Φmax, a non-negative number) reflects how much consciousness there is (the quantity of the experience). The irreducibility of each concept (φmax) reflects how much each phenomenal distinction exists within the experience. Different experiences correspond to different conceptual structures.
Ok then. Here we have a simple system that is having a conscious experience, ex hypothesi, and we know everything about this system. We know that it has these concepts specified by IIT, but what is it’s conscious experience like? What it is like to be this simple system of 4 logic gates when its elements A, B, and C are on? We aren’t told and there doesn’t seem to be any way to figure it out based on IIT. It seems to me that there should be no conscious experience associated with this activity, so it is easy to ‘conceive of a physical duplicate of this system with no conscious experience’…is this a zombie system? That is tongue in cheek but I guess that IIT proponents will need to say that since the identity is necessary I can’t really conceive of it (or that I can but it is not really possible). Can’t we conceive of two of these systems with inverted conscious experiences (same conceptual structures)? Why or why not? I can’t see anything in IIT that would help to answer these questions.
If IIT is attempting to provide a solution to the Hard Problem of Consciousness then should allow us to know what the conscious experience of this system is like, but it seems like it could be having any, or none (how difficult would it then be to extend this to Nagel’s bat!?!?). There are some who might object that this is asking too much. Isn’t this more like Ned Block’s “Harder Problem” than Chalmers’ Hard Problem? Here I suppose that I disagree with the overly narrow way of putting the Hard Problem. It isn’t merely about how this brain state is associated with a particular phenomenal quality rather than none at all, it is how it is associated with any physical, functional state at all that os the Hard Problem. Sure brain states are one kind of physical state and so the problem arises there but more generally the Hard Problem is answering the question of why any physical state is associated with any qualitative state at all instead of another or none at all.
IIT, and Tononi in particular, seem committed to giving us an answer. For instance, in his Scholarpedia article on IIT Tononi says,
IIT employs the postulates to derive, for any particular system of elements in a state, whether it has consciousness, how much, and of which kind.
But how do we do this for the 4 logic gates?
How do we do it in our own case?
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