The Missing Half of the Global Neuronal Workspace: A Commentary on Stanislaus Dehaene’s Consciousness and the Brain
Stanislaus Dehaene, to my mind at least, is the premier consciousness researcher on the planet, one of those rare scientists who seems equally at home in the theoretical aether (like we are here) and in the laboratory (where he is there). His latest book, Consciousness and the Brain provides an excellent, and at times brilliant, overview of the state of contemporary consciousness research. Consciousness has come a long way in the past two decades, and Dehaene deserves credit for much of the yardage gained.
I’ve been anticipating Consciousness and the Brain for quite some time, especially since I bumped across “The Eternal Silence of the Neuronal Spaces,” Dehaene’s review of Cristopher Koch’s Consciousness: Confessions of a Romantic Reductionist, where he concludes with a confession of his own: “Can neuroscience be reconciled with living a happy, meaningful, moral, and yet nondelusional life? I will confess that this question also occasionally keeps me lying awake at night.” Since the implications of the neuroscientific revolution, the prospects of having a technically actionable blueprint of the human soul, often keep my mind churning into the wee hours, I was hoping that I might see a more measured, less sanguine Dehaene in this book, one less inclined to soft-sell the troubling implications of neuroscientific research.
And in that one regard, I was disappointed. Consciousness and the Brain: Deciphering How the Brain Codes Our Thoughts is written for a broad audience, so in a certain sense one can understand the authorial instinct to make things easy for the reader, but rendering a subject matter more amenable to lay understanding is quite a different thing than rendering it more amenable to lay sensibilities. Dehaene, I think, caters far too much to the very preconceptions his science is in the process of dismantling. As a result, the book, for all its organizational finesse, all its elegant formulations, and economical summaries of various angles of research, finds itself haunted by a jagged shadow, the intimation that things simply are not as they seem. A contradiction—of expressive modes if not factual claims.
Perhaps the most stark example of this contradiction comes at the very conclusion of the book, where Dehaene finally turns to consider some of the philosophical problems raised by his project. Adopting a quasi-Dennettian argument (from Freedom Evolves) that the only ‘free will’ that matters is the free will we actually happen to have (namely, one compatible with physics and biology), he writes:
“Our belief in free will expresses the idea that, under the right circumstances, we have the ability to guide our decisions by our higher-level thoughts, beliefs, values, and past experiences, and to exert control over our undesired lower-level impulses. Whenever we make an autonomous decision, we exercise our free will by considering all the available options, pondering them, and choosing the one that we favor. Some degree of chance may enter in a voluntary choice, but this is not an essential feature. Most of the time our willful acts are anything but random: they consist in a careful review of our options, followed by the deliberate selection of the one we favor.” 264
And yet for his penultimate, concluding line no less, he writes, “[a]s you close this book to ponder your own existence, ignited assemblies of neurons literally make up your mind” (266). At this point, the perceptive reader might be forgiven for asking, ‘What happened to me pondering, me choosing the interpretation I favour, me making up my mind?’ The easy answer, of course, is that ‘ignited assemblies of neurons’ are the reader, such that whatever they ‘make,’ the reader ‘makes’ as well. The problem, however, is that the reader has just spent hours reading hundreds of pages detailing all the ways neurons act entirely outside his knowledge. If ignited assemblies of neurons are somehow what he is, then he has no inkling what he is—or what it is he is supposedly doing.
As we shall see, this pattern of alternating expressive modes, swapping between the personal and the impersonal registers to describe various brain activities, occurs throughout Consciousness and the Brain. As I mentioned above, I’m sure this has much to do with Dehaene’s resolution to write a reader friendly book, and so to market the Global Neuronal Workspace Theory (GNWT) to the broader public. I’ve read enough of Dehaene’s articles to recognize the nondescript, clinical tone that animates the impersonally expressed passages, and so to see those passages expressed in more personal idioms as self-conscious attempts on his part to make the material more accessible. But as the free will quote above makes plain, there’s a sense in which Dehaene, despite his odd sleepless night, remains committed to the fundamental compatibility of the personal and the impersonal idioms. He thinks neuroscience can be reconciled with a meaningful and nondelusional life. In what follows I intend to show why, on the basis of his own theory, he’s mistaken. He’s mistaken because, when all is said and done, Dehaene possesses only half of what could count as a complete theory of consciousness—the most important half to be sure, but half all the same. Despite all the detailed explanations of consciousness he gives in the book, he actually has no account whatsoever of what we seem to take consciousness to be–namely, ourselves.
For that account, Stanislaus Dehaene needs to look closely at the implicature of his Global Neuronal Workspace Theory—it’s long theoretical shadow, if you will—because there, I think, he will find my own Blind Brain Theory (BBT), and with it the theoretical resources to show how the consciousness revealed in his laboratory can be reconciled with the consciousness revealed in us. This, then, will be my primary contention: that Dehaene’s Global Neuronal Workspace Theory directly implies the Blind Brain Theory, and that the two theories, taken together, offer a truly comprehensive account of consciousness…
The one that keeps me lying awake at night.
Let’s look at a second example. After drawing up an inventory of varous, often intuition-defying, unconscious feats, Dehaene cautions the reader against drawing too pessimistic a conclusion regarding consciousness—what he calls the ‘zombie theory’ of consciousness. If unconscious processes, he asks, can plan, attend, sum, mean, read, recognize, value and so on, just what is consciousness good for? The threat of these findings, as he sees it, is that they seem to suggest that consciousness is merely epiphenomenal, a kind of kaliedoscopic side-effect to the more important, unconscious business of calculating brute possibilities. As he writes:
“The popular Danish science writer Tor Norretranders coined the term ‘user illusion’ to refer to our feeling of being in control, which may well be fallacious; every one of our decisions, he believes, stems from unconscious sources. Many other psychologists agree: consciousness is the proverbial backseat driver, a useless observer of actions that lie forever beyond its control.” 91
Dehaene disagrees, claiming that his account belongs to “what philosophers call the ‘functionalist’ view of consciousness” (91). He uses this passing criticism as a segue for his subsequent, fascinating account of the numerous functions discharged by consciousness—what makes consciousness a key evolutionary adaptation. The problem with this criticism is that it simply does not apply. Norretranders, for instance, nowhere espouses epiphenomenalism—at least not in The User Illusion. The same might be said of Daniel Wegner, one the ‘many psychologists,’ Dehaene references in the accompanying footnote. Far from epiphenomenalism, the argument that consciousness has no function whatsoever (as, say, Susan Pockett (2004) has argued), both of these authors contend that it’s ‘our feeling of being in control’ that is illusory. So in The Illusion of Conscious Will, for instance, Wegner proposes that the feeling of willing allows us to socially own our actions. For him, our consciousness of ‘control’ has a very determinate function, just one that contradicts our metacognitive intuition of that functionality.
Dehaene is simply in error here. He is confusing the denial of intuitions of conscious efficacy with a denial of conscious efficacy. He has simply run afoul the distinction between consciousness as it is and consciousness as appears to us—the distinction between consciousness as impersonally and personally construed. Note the way he actually slips between idioms in the passage quoted above, at first referencing ‘our feeling of being in control’ and then referencing ‘its control.’ Now one might think this distinction between these two very different perspectives on consciousness would be easy to police, but such is not the case (See Bennett and Hacker, 2003). Unfortunately, Dehaene is far from alone when it comes to running afoul this dichotomy.
For some time now, I’ve been arguing for what I’ve been calling a Dual Theory approach to the problem of consciousness. On the one hand, we need a theoretical apparatus that will allow us to discover what consciousness is as another natural phenomenon in the natural world. On the other hand, we need a theoretical apparatus that will allow us to explain (in a manner that makes empirically testable predictions) why consciousness appears the way that it does, namely, as something that simply cannot be another natural phenomenon in the natural world. Dehaene is in the business of providing the first kind of theory: a theory of what consciousness actually is. I’ve made a hobby of providing the second kind of theory: a theory of why consciousness appears to possess the baffling form that it does.
Few terms in the conceptual lexicon are quite so overdetermined as ‘consciousness.’ This is precisely what makes Dehaene’s operationalization of ‘conscious access’ invaluable. But salient among those traditional overdeterminations is the peculiarly tenacious assumption that consciousness ‘just is’ what it appears to be. Since what it appears to be is drastically at odds with anything else in the natural world, this assumption sets the explanatory bar rather high indeed. You could say consciousness needs a Dual Theory approach for the same reason that Dualism constitutes an intuitive default (Emmons 2014). Our dualistic intuitions arguably determine the structure of the entire debate. Either consciousness really is some wild, metaphysical exception to the natural order, or consciousness represents some novel, emergent twist that has hitherto eluded science, or something about our metacognitive access to consciousness simply makes it seem that way. Since the first leg of this trilemma belongs to theology, all the interesting action has fallen into orbit around the latter two options. The reason we need an ‘Appearance Theory’ when it comes to consciousness as opposed to other natural phenomena, has to do with our inability to pin down the explananda of consciousness, an inability that almost certainly turns on the idiosyncrasy of our access to the phenomena of consciousness compared to the phenomena of the natural world more generally. This, for instance, is the moral of Michael Graziano’s (otherwise flawed) Consciousness and the Social Brain: that the primary job of the neuroscientist is to explain consciousness, not our metacognitive perspective on consciousness.
The Blind Brain Theory is just such an Appearance Theory: it provides a systematic explanation of the kinds of cognitive confounds and access bottlenecks that make consciousness appear to be ‘supra-natural.’ It holds, with Dehaene, that consciousness is functional through and through, just not in any way we can readily intuit outside empirical work like Dehaene’s. As such, it takes findings such as Wegner’s, where the function we presume on the basis of intuition (free willing) is belied by some counter-to-intuition function (behaviour ownership), as paradigmatic. Far from epiphenomenalism, BBT constitutes a kind of ‘ulterior functionalism’: it acknowledges that consciousness discharges a myriad of functions, but it denies that metacognition is any position to cognize those functions (see “THE Something about Mary“) short of sustained empirical investigation.
Dehaene is certainly sensitive to the general outline of this problem: he devotes an entire chapter (“Consciousness Enters the Lab”) to discussing the ways he and others have overcome the notorious difficulties involved in experimentally ‘pinning consciousness down.’ And the masking and attention paradigms he has helped develop have done much to transform consciousness research into a legitimate field of scientific research. He even provides a splendid account of just how deep unconscious processing reaches into what we intuitively assume are wholly conscious exercises—an account that thoroughly identifies him as a fellow ulterior functionalist. He actually agrees with me and Norretranders and Wegner—he just doesn’t realize it quite yet.
The Global Neuronal Workspace
As I said, Dehaene is primarily interested in theorizing consciousness apart from how it appears. In order to show how the Blind Brain Theory actually follows from his findings, we need to consider both these findings and the theoretical apparatus that Dehaene and his colleagues use to make sense of them. We need to consider his Global Neuronal Workspace Theory of consciousness.
According to GNWT, the primary function of consciousness is to select, stabilize, solve, and broadcast information throughout the brain. As Dehaene writes:
“According to this theory, consciousness is just brain-wide information sharing. Whatever we become conscious of, we can hold it in our mind long after the corresponding stimulation has disappeared from the outside world. That’s because the brain has brought it into the workspace, which maintains it independently of the time and place at which we first perceived it. As a result, we may use it in whatever way we please. In particular, we can dispatch it to our language processors and name it; this is why the capacity to report is a key feature of a conscious state. But we can also store it in long-term memory or use it for our future plans, whatever they are. The flexible dissemination of information, I argue, is a characteristic property of a conscious state.” 165
A signature virtue of Consciousness and the Brain lays in Dehaene’s ability to blend complexity and nuance with expressive economy. But again one needs to be wary of his tendency to resort to the personal idiom, as he does in this passage, where the functional versatility provided by consciousness is explicitly conflated with agency, the freedom to dispose of information ‘in whatever way we please.’ Elsewhere he writes:
“The brain must contain a ‘router’ that allows it to flexibly broadcast information to and from its internal routines. This seems to be a major function of consciousness: to collect the information from various processors, synthesize it, and then broadcast the result–a conscious symbol–to other, arbitrarily selected processors. These processors, in turn, apply their unconscious skills to this symbol, and the entire process may repeat a number of times. The outcome is a hybrid serial-parallel machine, in which stages of massively parallel computation are interleaved with a serial stage of conscious decision making and information routing.” 105
Here we find him making essentially the same claims in less anthropomorphic or ‘reader-friendly’ terms. Despite the folksy allure of the ‘workspace’ metaphor, this image of the brain as a ‘hybrid serial-parallel machine’ is what lies at the root of GNWT. For years now, Dehaene and others have been using masking and attention experiments in concert with fMRI, EEG, and MEG to track the comparative neural history of conscious and unconscious stimuli through the brain. This has allowed them to isolate what Dehaene calls the ‘signatures of consciousness,’ the events that distinguish percepts that cross the conscious threshold from percepts that do not. A theme that Dehaene repeatedly evokes is the information asymmetric nature of conscious versus unconscious processing. Since conscious access is the only access we possess to our brain’s operations, we tend to run afoul a version of what Daniel Kahneman (2012) calls WYSIATI, or the ‘what-you-see-is-all-there-is’ effect. Dehaene even goes so far as to state this peculiar tendency as a law: “We constantly overestimate our awareness—even when we are aware of glaring gaps in our awareness” (79). The fact is the nonconscious brain performs the vast, vast majority of the brain’s calculations.
The reason for this has to do with the Inverse Problem, the challenge of inferring the mechanics of some distal system, a predator or a flood, say, from the mechanics of some proximal system such as ambient light or sound. The crux of the problem lies in the ambiguity inherent to the proximal mechanism: a wild variety of distal events could explain any given retinal stimulus, for instance, and yet somehow we reliably perceive predators or floods or what have you. Dehaene writes:
“We never see the world as our retina sees it. In fact, it would be a pretty horrible sight: a highly distorted set of light and dark pixels, blown up toward the center of the retina, masked by blood vessels, with a massive hole at the location of the ‘blind spot’ where cables leave for the brain; the image would constantly blur and change as our gaze moved around. What we see, instead, is a three-dimensional scene, corrected for retinal defects, mended at the blind spot, and massive reinterpreted based on our previous experience of similar visual scenes.” 60
The brain can do this because it acts as a massively parallel Bayesian inference engine, analytically breaking down various elements of our retinal images, feeding them to specialized heuristic circuits, and cobbling together hypothesis after hypothesis.
“Below the conscious stage, myriad unconscious processors, operating in parallel, constantly strive to extract the most detailed and complete interpretation of our environment. They operate as nearly optimal statisticians who exploit the slightest perceptual hint—a faint movement, a shadow, a splotch of light—to calculate the probability that a given property holds true in the outside world.” 92
But hypotheses are not enough. All this machinery belongs to what is called the ‘sensorimotor loop.’ The whole evolutionary point of all this processing is to produce ‘actionable intelligence,’ which is to say, to help generate and drive effective behaviour. In many cases, when the bottom-up interpretations match the top-down expectations and behaviour is routine, say, such selection need not result in consciousness of the stimuli at issue. In other cases, however, the interpretations are relayed to the nonconscious attentional systems of the brain where they are ranked according to their relevance to ongoing behaviour and selected accordingly for conscious processing. Dehaene summarizes what happens next:
“Conscious perception results from a wave of neuronal activity that tips the cortex over its ignition threshold. A conscious stimulus triggers a self-amplifying avalanche of neural activity that ultimately ignites many regions into a tangled state. During that conscious state, which starts approximately 300 milliseconds after stimulus onset, the frontal regions of the brain are being informed of sensory inputs in a bottom-up manner, but these regions also send massive projections in the converse direction, top-down, and to many distributed areas. The end result is a brain web of synchronized areas whose various facets provide us with many signatures of consciousness: distributed activation, particularly in the frontal and parietal lobes, a P3 wave, gamma-band amplification, and massive long-distance synchrony.” 140
As Dehaene is at pains to point out, the machinery of consciousness is simply too extensive to not be functional somehow. The neurophysiological differences observed between the multiple interpretations that hover in nonconscious attention, and the interpretation that tips the ‘ignition threshold’ of consciousness is nothing if not dramatic. Information that was localized suddenly becomes globally accessible. Information that was transitory suddenly becomes stable. Information that was hypothetical suddenly becomes canonical. Information that was dedicated suddenly becomes fungible. Consciousness makes information spatially, temporally, and structurally available. And this, as Dehaene rightly argues, makes all the difference in the world, including the fact that “[t]he global availability of information is precisely what we subjectively experience as a conscious state” (168).
A Mile Wide and an Inch Thin
Consciousness is the Medieval Latin of neural processing. It makes information structurally available, both across time and across the brain. As Dehaene writes, “The capacity to synthesize information over time, space, and modalities of knowledge, and to rethink it at any time in the future, is a fundamental component of the conscious mind, one that seems likely to have been positively selected for during evolution” (101). But this evolutionary advantage comes with a number of crucial caveats, qualifications that, as we shall see, make some kind of Dual Theory approach unavoidable.
Once an interpretation commands the global workspace, it becomes available for processing via the nonconscious input of a number of different processors. Thus the metaphor of the workspace. The information can be ‘worked over,’ mined for novel opportunities, refined into something more useful, but only, as Dehaene points out numerous times, synoptically and sequentially.
Consciousness is synoptic insofar as it samples mere fractions of the information available: “An unconscious army of neurons evaluates all the possibilities,” Dehaene writes, “but consciousness receives only a stripped down report” (96). By selecting, in other words, the workspace is at once neglecting, not only all the alternate interpretations, but all the neural machinations responsible: “Paradoxically, the sampling that goes on in our conscious vision makes us forever blind to its inner complexity” (98).
And consciousness is sequential in that it can only sample one fraction at a time: “our conscious brain cannot experience two ignitions at once and lets us perceive only a single conscious ‘chunk’ at a given time,” he explains. “Whenever the prefrontal and parietal lobes are jointly engaged in processing a first stimulus, they cannot simultaneously reengage toward a second one” (125).
All this is to say that consciousness pertains to the serial portion of the ‘hybrid serial-parallel machine’ that is the human brain. Dehaene even goes so far as to analogize consciousness to a “biological Turing machine” (106), a kind of production system possessing the “capacity to implement any effective procedure” (105). He writes:
“A production system comprises a database, also called ‘working memory,’ and a vast array of if-then production rules… At each step, the system examines whether a rule matches the current state of its working memory. If multiple rules match, then they compete under the aegis of a stochastic prioritizing system. Finally, the winning rule ‘ignites’ and is allowed to change the contents of working memory before the entire process resumes. Thus this sequence of steps amounts to serial cycles of unconscious competition, conscious ignition, and broadcasting.” 105
The point of this analogy, Dehaene is quick to point out, isn’t to “revive the cliché of the brain as a classical computer” (106) so much as it is to understand the relationship between the conscious and nonconscious brain. Indeed, in subsequent experiments, Dehaene and his colleagues discovered that the nonconscious, for all its computational power, is generally incapable of making sequential inferences: “The mighty unconscious generates sophisticated hunches, but only a conscious mind can follow a rational strategy, step after step” (109). It seems something of a platitude to claim that rational deliberation requires consciousness, but to be able to provide an experimentally tested neurobiological account of why this is so is nothing short of astounding. Make no mistake: these are the kind of answers philosophy, rooting through the mire of intuition, has sought for millennia.
Dehaene, as I mentioned, is primarily interested in providing a positive account of what consciousness is apart from what we take it to be. “Putting together all the evidence inescapably leads us to a reductionist conclusion,” Dehaene writes. “All our conscious experiences, from the sound of an orchestra to the smell of burnt toast, result from a similar source: the activity of massive cerebral circuits that have reproducible neuronal signatures” (158). Though he does consider several philosophical implications of his ‘reductionist conclusions,’ he does so only in passing. He by no means dwells on them.
Given that consciousness research is a science attempting to bootstrap its way out of the miasma of philosophical speculation regarding the human soul, this reluctance is quite understandable—perhaps even laudable. The problem, however, is that philosophy and science both traffic in theory, general claims about basic things. As a result, the boundaries are constitutively muddled, typically to the detriment of the science, but sometimes to its advantage. A reluctance to speculate may keep the scientist safe, but to the extent that ‘data without theory is blind,’ it may also mean missed opportunities.
So consider Dehaene’s misplaced charge of epiphenomenalism, the way he seemed to be confusing the denial of our intuitions of conscious efficacy with the denial of conscious efficacy. The former, which I called ‘ulterior functionalism,’ entirely agrees that consciousness possesses functions; it denies only that we have reliable metacognitive access to those functions. Our only recourse, the ulterior functionalist holds, is to engage in empirical investigation. And this, I suggested, is clearly Dehaene’s own position. Consider:
“The discovery that a word or a digit can travel throughout the brain, bias our decisions, and affect our language networks, all the while remaining unseen, was an eye-opener for many cognitive scientists. We had underestimated the power of the unconscious. Our intuitions, it turned out, could not be trusted: we had no way of knowing what cognitive processes could or could not proceed without awareness. The matter was entirely empirical. We had to submit, one by one, each mental faculty to a thorough inspection of its component processes, and decide which of those faculties did or did not appeal to the conscious mind. Only careful experimentation could decide the matter…” 74
This could serve as a mission statement for ulterior functionalism. We cannot, as a matter of fact, trust any of our prescientific intuitions regarding what we are, no more than we could trust our prescientific intuitions regarding the natural world. This much seems conclusive. Then why does Dehaene find the kinds of claims advanced by Norretranders and Wegner problematic? What I want to say is that Dehaene, despite the occasional sleepless night, still believes that the account of consciousness as it is will somehow redeem the most essential aspects of consciousness as it appears, that something like a program of ‘Dennettian redefinition’ will be enough. Thus the attitude he takes toward free will. But then I encounter passages like this:
“Yet we never truly know ourselves. We remain largely ignorant of the actual unconscious determinants of our behaviour, and therefore cannot accurately predict what our behaviour will be in circumstances beyond the safety zone of our past experiences. The Greek motto ‘Know thyself,’ when applied to the minute details of our behaviour, remains an inaccessible ideal. Our ‘self’ is just a database that gets filled in through our social experiences, in the same format with which we attempt to understand other minds, and therefore it is just as likely to include glaring gaps, misunderstandings, and delusions.” 113
Claims like this, which radically contravene our intuitive, prescientific understanding of self, suggest that Dehaene simply does not know where he stands, that he alternately believes and does not believe that his work can be reconciled with our traditional understand of ‘meaningful life.’ Perhaps this explains the pendulum swing between the personal and the impersonal idiom that characterizes this book—down to the final line, no less!
Even though this is an eminently honest frame of mind to take to this subject matter, I personally think his research cuts against even this conflicted optimism. Not surprisingly, the Global Neuronal Workspace Theory of Consciousness casts an almost preposterously long theoretical shadow; it possesses an implicature that reaches to the furthest corners of the great human endeavour to understand itself. As I hope to show, the Blind Brain Theory of the Appearance of Consciousness provides a parsimonious and powerful way to make this downstream implicature explicit.
From Geocentrism to ‘Noocentrism’
“Most mental operations,” Dehaene writes, “are opaque to the mind’s eye; we have no insight into the operations that allow us to recognize a face, plan a step, add two digits, or name a word” (104-5). If one pauses to consider the hundreds of experiments that he directly references, not to mention the thousands of others that indirectly inform his work, this goes without saying. We require a science of consciousness simply because we have no other way of knowing what consciousness is. The science of consciousness is literally predicated on the fact of our metacognitive incapacity (See “The Introspective Peepshow“).
Demanding that science provide a positive explanation of consciousness as we intuit it is no different than demanding that science provide a positive explanation of geocentrism—which is to say, the celestial mechanics of the earth as we once intuited it. Any fool knows that the ground does not move. If anything, the fixity of the ground is what allows us to judge movement. Certainly the possibility that the earth moved was an ancient posit, but lacking evidence to the contrary, it could be little more than philosophical fancy. Only the slow accumulation of information allowed us to reconceive the ‘motionless earth’ as an artifact of ignorance, as something that only the absence of information could render obvious. Geocentrism is the product of a perspectival illusion, plain and simple, the fact that we literally stood too close to the earth to comprehend what the earth in fact was.
We stand even closer to consciousness—so close as to be coextensive! Nonetheless, a good number of very intelligent people insist on taking (some version of) consciousness as we intuit it to be the primary explanandum of consciousness research. Given his ‘law’ (We constantly overestimate our awareness—even when we are aware of glaring gaps in our awareness” (79)), Dehaene is duly skeptical. He is a scientific reductionist, after all. So with reference to David Chalmers’ ‘hard problem’ of consciousness, we find him writing:
“My opinion is that Chalmers swapped the labels: it is the ‘easy’ problem that is hard, while the hard problem just seems hard because it engages ill-defined intuitions. Once our intuition is educated by cognitive neuroscience and computer simulations, Chalmer’s hard problem will evaporate.” 262
Referencing the way modern molecular biology has overthrown vitalism, he continues:
“Likewise, the science of consciousness will keep eating away at the hard problem until it vanishes. For instance, current models of visual perception already explain not only why the human brain suffers from a variety of visual illusions but also why such illusions would appear in any rational machine confronted with the same computational problem. The science of consciousness already explains significant chunks of our subjective experience, and I see no obvious limits to this approach.” 262
I agree entirely. The intuitions underwriting the so-called ‘hard problem’ are perspectival artifacts. As in the case of geocentrism, our cognitive systems stand entirely too close to consciousness to not run afoul a number of profound illusions. And I think Dehaene, not unlike Galileo, is using the ‘Dutch Spyglass’ afforded by masking and attention paradigms to accumulate the information required to overcome those illusions. I just think he remains, despite his intellectual scruples, a residual hostage of the selfsame intuitions he is bent on helping us overcome.
Dehaene only needs to think through the consequences of GNWT as it stands. So when he continues to discuss other ‘hail Mary’ attempts (those of Eccles and Penrose) to find some positive account of consciousness as it appears, writing that “the intuition that our mind chooses its actions ‘at will’ begs for an explanation” (263), I’m inclined to think he already possesses the resources to advance such an explanation. He just needs to look at his own findings in a different way.
Consider the synoptic and sequential nature of what Dehaene calls ‘ignition,’ the becoming conscious of some nonconscious interpretation. The synoptic nature of ignition, the fact that consciousness merely samples interpretations, means that consciousness is radically privative, that every instance of selection involves massive neglect. The sequential nature of ignition, on the other hand, the fact that the becoming conscious of any interpretation precludes the becoming conscious of another interpretation, means that each moment of consciousness is an all or nothing affair. As I hope to show, these two characteristics possess profound implications when applied to the question of human metacognitive capacity—which is to say, our capacity to intuit our own makeup.
Dehaene actually has very little to say regarding self-consciousness and metacognition in Consciousness and the Brain, aside from speculating on the enabling role played by language. Where other mammalian species clearly seem to possess metacognitive capacity, it seems restricted to the second-order estimation of the reliability of their first-order estimations. They lack “the potential infinity of concepts that a recursive language affords” (252). He provides an inventory of the anatomical differences between primates and other mammals, such as specialized ‘broadcast neurons,’ and between humans and their closest primate kin, such as the size of the dendritic trees possessed by human prefrontal neurons. As he writes:
“All these adaptations point to the same evolutionary trend. During hominization, the networks of our prefrontal cortex grew denser and denser, to a larger extent than would be predicted by brain size alone. Our workspace circuits expanded way beyond proportion, but this increase is probably just the tip of the iceberg. We are more than just primates with larger brains. I would not be surprised if, in the coming years, cognitive neuroscientists find that the human brain possesses unique microcircuits that give it access to a new level of recursive, language-like operations.” 253
Presuming the remainder of the ‘iceberg’ does not overthrow Dehaene’s workspace paradigm, however, it seems safe to assume that our metacognitive machinery feeds from the same informational trough, that it is simply one among the many consumers of the information broadcast in conscious ignition. The ‘information horizon’ of the Workspace, in other words, is the information horizon of conscious metacognition. This would be why our capacity to report seems to be coextensive with our capacity to consciously metacognize: the information we can report constitutes the sum of information available for reflective problem-solving.
So consider the problem of a human brain attempting to consciously cognize the origins of its own activity—for the purposes of reporting to other brains, say. The first thing to note is that the actual, neurobiological origins of that activity are entirely unavailable. Since only information that ignites is broadcast, only information that ignites is available. The synoptic nature of the information ignited renders the astronomical complexities of ignition inaccessible to conscious access. Even more profoundly, the serial nature of ignition suggests that consciousness, in a strange sense, is always too late. Information pertaining to ignition can never be processed for ignition. This is why so much careful experimentation is required, why our intuitions are ‘ill-defined,’ why ‘most mental operations are opaque.’ The neurofunctional context of the workspace is something that lies outside the capacity of the workspace to access.
This explains the out-and-out inevitability of what I called ‘ulterior functionalism’ above: the information ignited constitutes the sum of the information available for conscious metacognition. Whenever we interrogate the origins or our conscious episodes, reflection only has our working memory of prior conscious episodes to go on. This suggests something as obvious as it is counterintuitive: that conscious metacognition should suffer a profound form of source blindness. Whenever conscious metacognition searches for the origins of its own activity, it finds only itself.
Free will, in other words, is a metacognitive illusion arising out of the structure of the global neuronal workspace, one that, while perhaps not appearing “in any rational machine confronted with the same computational problem” (262), would appear in any conscious system possessing the same structural features as the global neuronal workspace. The situation is almost directly analogous to the situation faced by our ancestors before Galileo. Absent any information regarding the actual celestial mechanics of the earth, the default assumption is that the earth has no such mechanics. Likewise, absent any information regarding the actual neural mechanics of consciousness, the default assumption is that consciousness also has no such mechanics.
But free will is simply one of many problems pertaining to our metacognitive intuitions. According to the Blind Brain Theory of the Appearance of Consciousness, a great number of the ancient and modern perplexities can be likewise explained in terms of metacognitive neglect, attributed to the fact that the structure and dynamics of the workspace render the workspace effectively blind to its own structure and dynamics. Taking Dehaene’s Global Neuronal Workspace Theory of Consciousness, it can explain away the ‘ill-defined intuitions’ that underwrite attributions of some extraordinary irreducibility to conscious phenomena.
On BBT, the myriad structural peculiarities that theologians and philosophers have historically attributed to the first person are perspectival illusions, artifacts of neglect—things that seem obvious only so long as we remain ignorant of the actual mechanics involved (See, “Cognition Obscura“). Our prescientific conception of ourselves is radically delusional, and the kind of counterintuitive findings Dehaene uses to patiently develop and explain GNWT are simply what we should expect. Noocentrism is as doomed as was geocentrism. Our prescientific image of ourselves is as blinkered as our prescientific image of the world, a possibility which should, perhaps, come as no surprise. We are simply another pocket of the natural world, after all.
But the overthrow of noocentrism is bound to generate even more controversy than the overthrow of geocentrism or biocentrism, given that so much of our self and social understanding relies upon this prescientific image. Perhaps we should all lay awake at night, pondering our pondering…