Okay, deep breath.
I'm doing some highly integrative neuroscience - I'm applying complex information-theoretic measures to human neural data, in such a way that behavioral data produced by those humans can guide my interpretations. It's complicated.
The theory I'm working under is called the Integrated Information Theory (IIT) of consciousness. Consciousness is a fraught area of science and philosophy - everyone has an opinion, even if they think they don't - and the people who know their opinions are really, really excited about them. Some of those people are kind of weird. But the IIT, I think, is actually a rather mundane theory - it's very abstract on the one hand, but it doesn't, by its nature, make any big metaphysical claims about existence, or try to tie itself to evolution or quantum physics. Rather, the IIT aims to be a theory of the neural correlates of consciousness (NCCs) - why is it that some parts of the brain correspond to conscious experience, while others don't? At this level, it competes with other theories of NCC, most notably the Global Neuronal Workspace theory (GNW), although they take opposite approaches - the GNW looks first at the brain, at the NCCs themselves, and tries to explain the specific neural processes that we can see, objectively, are producing consciousness. The IIT, on the other hand, looks first at conscious experience, and, from the inside-out, tries to explain what properties consciousness has by proposing an algorithmic or mathematical expression of that experience.
I know the IIT better than the GNW, and I prefer the approach of the IIT, but I think that eventually these two theories will meet in the middle, and we'll have a real, general theory of consciousness. Might not be for a while, but it will happen.
What the GNW gives you is a description of the brain's mechanics, and post-hoc philosophizing about how certain types of connections in the brain distribute information throughout a central network, and that this distribution is the promotion of something to the status of consciousness. This is based on seeing, objectively, that these things are correlated, so the GNW is a theory of the NCCs at its very root. To some eyes, this makes it the more plausible competitor, since it's based in objective reality.
The IIT, being based in subjective experience (by extracting 'axioms' about consciousness - it's integrated, it's informative, it's bounded, it has structure) is different from the GNW especially in that it isn't specifically based on any principles of neuroscience. It's a mathematical theory, a theory of information transmission in networks. It is, of course, expressed with the obvious intention of being applied to facts of neuroscience, and it seems to do well in this respect. Put simply (I'm obviously not trying to explain the IIT here), if you point the IIT at a brain, it should give you back a prediction (you know what I mean) of whether or not that brain is conscious, which parts are doing the job, and how the doing is organized. This last part is one thing that makes the IIT so interesting - it gives a way of describing the internal structure of what it claims is conscious experience.
So, this is what the IIT is intended for - to predict how consciousness arises in a brain. In this it is indeed falsifiable. An attack I've seen on the IIT from several sources - most recently some of the duller commenters on Scott Aaronson's much better attack - is that it isn't falsifiable, but this is clearly not correct. Tononi (the theorist behind the IIT) gives one clear example of how to falsify the theory: take two substances, both of which disrupt neural activity, but only one of which degrades the capacity of the brain to integrate information (in the specific terms of the theory). You could equalize the substances in other ways - make it so that one impairs attention, or some other manipulation that under a given theory should destroy consciousness - and then find out whether or not your (human) subject has lost consciousness. The IIT should predict exactly which interventions disrupt consciousness and which do not. In fact, it should predict which parts of consciousness are degraded - is vision lost, or hearing, or etc. If the theory fails, then it's wrong. So, the IIT is falsifiable.
But when the critics say it's unfalsifiable, they aren't thinking about the object of the theory - human (or animal) consciousness. They're thinking about panpsychism, and thus missing the whole point. It's true - the IIT predicts that systems that aren't brains can possess consciousness, and that it can be completely alien to human consciousness - no perception or cognition, for example. To many people this is 1) totally incoherent (this is Aaronson's criticism) and 2) unfalsifiable and thus the mark of a bad theory. But that a theory generates unfalsifiable statements is never grounds for dismissing the theory - thsi is basic logic (cf. Popper). What matters it that, in the realm where it's meant to explain something, the theory does its job. If you have two theories that explain equally well, but one generates incoherent, untestable predictions, then you can proceed with parsimony, but you have to have the alternative first. Occam's razor can't be used when you have no competition (unless you'd rather have no theory at all - and this is an ideological point rather than a scientific approach to a problem).
And anyways, even the panpsychism problem (taking the meaning of panpsychism very loosely, since IIT doesn't predict that everything is conscious - just that things that aren't brains can be conscious) isn't definitely untestable - the theory predicts that different conscious things are, in principle at least, linkable. So, if IIT says that a certain not-a-brain system is conscious, then the IIT adherent can simply plug his brain into the object, and if the theory predicts that the adherent's consciousness is linked to the not-a-brain system, then firsthand knowledge is the proper test. That's science fiction stuff there (the film Pacific Rim's drift technology was an implementation of the idea), but the IIT says it's technically possible. So, the ultimate test of the IIT might turn out to be technology - if every IIT-based device fails to produce predicted effects on consciousness, then the theory will be abandoned.
That's all I have for now. June is almost over. One more month in Australia, then home. Back to the grind...
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