Many cognitive neuroscientists interested in explaining consciousness often define it as that which distinguishes an awake and alert mammal from a mammal in a coma. This is essentially what Bernard Baars takes himself to be explaining with his Global Workspace model. The idea is that being awake and alert with an active global workspace is what accounts for the intelligence and vigor of awake humans as opposed to sleeping humans or humans in comas. More specifically, Baars operationalizes consciousness to be such that “We will consider people to be conscious of an event if (1) they can say immediately after they were conscious of it and (2) we can independently verify the accuracy of the report”. It must be understood that “report” doesn’t necessarily mean verbal report either, otherwise the Global Workspace model couldn’t be applied to nonhuman mammals (which Baars clearly thinks it does). Of course, there are good methodological reasons for operationalizing consciousness, and Baars does admit that the operational definition might miss some unreportable experiences.
On the GW model, the ability to nonverbally “report” on a conscious experience is dependent on there being a global broadcasting system in the brain. I’m simplifying the complexity of the model greatly, but the basic idea is that behind such an ability to report is a GW that enables complex, intelligent, goal-directed behavior that just isn’t there when we are sleeping or in a coma. Without a GW there is just a diverse network of specialized processors that operate quickly, automatically, and in a massively parallel fashion. Such specialized processors can accomplish quite a bit on their own, but without the GW there is a lack of coherence that is the sign of awake, intelligent mammalian behavior.
With that said, I’m just not sure that it’s best to define consciousness as the difference maker between sleep and wakefulness in mammals. While I believe there is indeed a phenomenological difference between sleep and wakefulness, I’m not sure the phenomenological difference is a difference in consciousness since I don’t define consciousness in terms of whether it bestows phenomenology or not. It seems to me that what Baars is really getting at with his GW model is an explanation of how it’s possible that awake mammals are so intelligent compared to sleeping mammals, mammals in a coma, or creatures with much less complicated nervous systems. What I think Baars is getting at then is an explanation of the high end of a spectrum of intelligent reactivity. All organisms react to their environments in an appropriate way. This can be seen as a kind of intelligence. But with a mammalian brain outfitted with a GW, the complexity of intelligent reactivity is far greater because the GW allows for a higher-order level of coordination between disparate specialized processors. And there is undoubtedly a phenomenological difference when such a GW is active compared to when it’s not. But do we really need to invoke consciousness to explain this change in phenomenology and behavior when you have a GW? Since I have argued elsewhere that even nonneural organisms possess phenomenal consciousness, the GW model cannot be a reductive account of the origin of what-it-is-likeness. What other concepts of consciousness are left? Well, there is the introspective consciousness of humans. But Baars is explicit that his GW model is not a model of introspection. So where does consciousness come into the picture?
In my preferred phenomenological taxonomy the greatest qualitative shift in phenomenology comes when you possess the capacity for introspective consciousness. If you don’t have introspective consciousness, then I believe the differences in phenomenology from simple to complex creatures and from sleep to wakefulness are matters of degree. But with introspective consciousness I believe there is a radical qualitative shift in what-it-is-likeness. For this reason, I prefer to follow Julian Jaynes in restricting the definition of consciousness to introspective consciousness, dropping “consciousness” from phenomenal consciousness and just calling it phenomenality.
So on my preferred definition I don’t think the GW model is a model of consciousness. However, I do believe that the shared architecture of GW in humans might provide a neurological scaffold upon which to build the uniquely human capacity for introspective consciousness (I think you will need some kind linguistic input for such a construction). So the GW model might still be important for accounting for what I am calling consciousness, provided that it is only a foundation akin to Michael Anderson’s “Massive redeployment hypothesis”. The idea then is that in humans the GW gets redeployed to help instantiate complex introspective activities, which then in turn greatly change what-it-is-like to be us.
I take Baars and the GW model very seriously. Baars is a brilliant scientist and knows his science very well. But I just do not agree that it’s best to define consciousness such that it distinguishes wakefulness from coma. I believe we already have a vocabulary useful for describing what the GW is an account of in terms of greater degrees of intelligent reactivity in virtue of higher levels of coordination between specialized processors. Obviously such coordination will enable complex intelligent behavior that seems to warrant ascriptions of phenomenal experience. But since GW is not an account of either phenomenal or introspective consciousness, I don’t think we really need to talk about consciousness when talking about the GW model. As Julian Jaynes said,
“Reactivity covers all stimuli my behavior takes account of in any way, while consciousness is something quite distinct and a far less ubiquitous phenomenon. We are conscious of what we are reacting to only from time to time.”
In my view, GW theory is capable of explaining certain kinds of reactivity unique to mammals with special types of globally connected brain architectures. But unless we use the foundations of GW theory to account for introspective consciousness, I do not see GW theory as offering an explanation of consciousness. But since this is really a terminological quibble, don’t interpret me as thinking that I believe the GW is false. If we properly understood what GW is in fact trying to explain with its operational definition, then GW is an enormous empirical success and should be praised as such. But as a philosopher I am very particular about terminology. Of course, Baars is just following the current mainstream in defining consciousness such that it’s evolutionarily ancient and shared with mammals. And he’s perfectly justified in defining his terms however he wants. But I guess I am stubborn about defining consciousness such that it ends up being relatively rare in the animal world.