These are encouraging times for secularists – atheists, humanists, freethinkers and skeptics – with recent U.S. surveys showing substantial increases in those unaffiliated with any mainstream religion. This might be an indication that belief in a supernatural divinity, at least of the traditional Christian variety, is on the wane. Atheists are certainly making themselves heard via billboard campaigns, reinvigorated secular organizations, and a slew of books questioning belief in God and the advisability of faith. Ron Aronson, author of Living Without God, argues at Religion Dispatches that there may be more secularists out there than meets the eye.

For those in the business of advancing naturalism this is of course good news, since atheism and humanism are significant milestones on the way to a fully naturalistic view of reality. But after God is gone there’s still a ways to go. Even after giving up belief in the supernatural “up there,” many atheists and humanists continue to harbor quasi-supernatural intuitions about the self and free will “in here.” The little god of the soul, the categorically mental agent or homunculus in charge of the brain, is still alive and well in the thinking of many secularists. As a result, some of the most profound developments in the ongoing project of scientific enlightenment are still ahead of us.

I am pleased to report that Thomas Metzinger’s The Ego Tunnel is a major contribution to this project, written for the curious and fearless lay person wanting to know who, precisely, we are. I strongly recommend this book. Here is the self fully naturalized, a radical revision of the conventional wisdom about our essential nature – are you ready? It’s also a must read for anyone interested in consciousness and the mind-body problem, since Metzinger has a well-developed, empirically supported representational theory that explains many of the puzzles about conscious subjectivity.

His two main themes, self and consciousness, are closely linked, and they culminate in two rather unsettling conclusions. First, selves don’t exist in the way most folks suppose. Second, the solid, three dimensional public reality that is so palpably there in our waking lives turns out to be a private model of reality. On Metzinger’s view, the self – the feeling of being a mental me in charge of the physical body – is a module within consciousness activated by your brain’s neural processing. The self is categorically not some substantial, essential invariant entity, like a soul, spirit or homunculus. As he emphasizes, there are no such things as substantial selves. Instead, the self is a phenomenal (that is, experiential) construct that disintegrates entirely when you fall into a dreamless sleep, to be reactivated (usually in attenuated form) when you dream, and that reappears nearly instantaneously when you awake in the morning. The self is put online only when needed, part of a larger phenomenal reality generated by the brain as it represents the world and you in it. This reality seems perfectly concrete, but the startling fact of the matter, a challenge to naïve realists (that is, just about everybody), is that it’s an appearance, a virtual reality. You, the subject conjured up by the brain, do not directly encounter the world. Rather, you participate in a larger brain-based representational construction – consciousness – that maps the actual world closely enough for you-the-organism to stay out of trouble. This global simulation carried out in each of our heads, what we can’t help but take as real, is what Metzinger calls the Ego Tunnel. Welcome to the Matrix.

Explaining consciousness: the appearance of a world

The obvious difficulty Metzinger faces is to make all this plausible, given the many competing explanations of consciousness and their conceptual complexity. Indeed, he quotes philosopher Daniel Dennett at the very start: “Any theory that makes progress is bound to be initially counterintuitive” (original emphasis). He acknowledges we’re just beginning to understand the mind-brain, but he’s confident that his representational approach, one of the major contenders in consciousness studies, is very likely correct in its essentials. The full exposition of his theory, daunting in its intricacy but ultimately very rewarding, can be found in his 2003 tour de force Being No One: The Self-Model Theory of Subjectivity. So if you find The Ego Tunnel philosophically or empirically sketchy, look there. As I advised a philosophy grad student recently: “Try Being No One, you might like it.”

The Ego Tunnel is reasonably demanding in its own right, given the breadth of material and its undeniable strangeness for those encountering the self-model theory for the first time. Even for veterans of consciousness studies it offers much that’s worthwhile and likely new: some mind-stretching thought experiments; interviews with researchers on the binding problem (the unity of consciousness), dreams, and empathy; and an imagined conversation with a post-biotic philosopher who pities us merely human thinkers, stuck in our crude reality models (this is just one of several well-timed dessert moments in the book). Metzinger is a first rate, albeit human, neurophilosopher, fully cognizant of mind science as well as philosophy, and a very good writer in his second language (German the first). You might occasionally get boggled and baffled as you negotiate The Ego Tunnel, but never bored. The main thing is that you’re getting a glimpse behind (what you might not yet realize is) the veil of consciousness, in a sense escaping the tunnel into non-subjective reality, if only conceptually. You’re also getting a preview of what our lives might be like under a radically revised notion of self, should the “consciousness revolution” Metzinger contemplates come to pass. There might be, he suggests, some profound personal and social consequences that follow from fully naturalizing ourselves.

The first third of the book covers the basic theoretical model: that consciousness is for a world to appear, both in its basic phenomenal (experiential) particulars – what are often called qualia, e.g., the redness of red, the painfulness of pain – and in its global unity: we never find pain, red, or any other quality on its own, but always within a larger coherent conscious context of self-in-the-world. In contrast to anti-representationalist philosophers such as Alva Noe and Kevin O’Regan, Metzinger holds that consciousness is an internal matter, in that the brain’s neural properties completely determine the subjective qualities and content of experience. As philosophers sometimes put it, experience supervenes locally on brain states. Although we ordinarily have experience in the context of getting around in the world, the world itself isn’t necessary for consciousness: were your brain in the same state it is now, absent the world, you’d be having the exact same experience. Dreams, especially lucid dreams, are evidence for this. When dreaming, the brain is conjuring up a 3-D world, with you in it, while you’re lying paralyzed in bed. In a lucid dream, in which you know you’re dreaming, you actually experience the fact that experience is being constructed by your brain – quite an astonishing gut-level revelation I recommend to everyone interested in consciousness. (Metzinger discusses how to induce lucid dreams, about which more below.)

Metzinger likens consciousness to a tunnel since it’s a very selective, narrow representation of the world:

What we see and hear, or what we feel and smell and taste, is only a small fraction of what actually exists out there. Our conscious model of reality is a low-dimensional projection of the inconceivably richer physical reality surrounding us and sustaining us. Our sensory organs are limited: They evolved for reasons of survival, not for depicting the enormous wealth and richness of reality in all its unfathomable depth. Therefore, the ongoing process of conscious experience is not so much an image of reality as a tunnel through reality.” (p. 6, original emphasis)

Consciousness is an ego tunnel since it nearly always includes the experience of being a self or subject – the entity to whom the world of experience appears (exceptions are more or less self-less states induced by brain disorders, meditation, drugs, or other means). Not only does the brain construct a phenomenal model of the world, it constructs a phenomenal model of someone in the world who interacts with it and knows it – that is, you. The basic trick of consciousness is to hide the fact that this phenomenal self-model, and the larger reality-model it’s embedded in, is indeed a model: it’s transparent in the sense that you can’t experience it as a model. Rather, you look right through it and simply find yourself present in a world. For the conscious subject, reality is just that which can’t be experienced as a construction.

For Metzinger, subjectivity – the “who problem” of being a self – is the most difficult and profound aspect of consciousness in need of explanation, but there are other general features of consciousness which he explores in a “tour” of the Ego Tunnel. Consciousness is always an experienced unity; it’s always now, that is, temporally present; it convinces us that it’s real, not a representation; it transcends our ability to describe its basic elements, so is ineffable in some respects; and it has come about via evolution, thus is natural and adaptive. In laying out these parameters, Metzinger is taking care to specify the explanatory target of his theory, something too many consciousness researchers gloss over. It’s only by getting a clear fix on the phenomenal properties of consciousness that we can make progress in explaining it. Although his explanations are cursory compared to what’s offered in Being No One, the basic strategy is to connect the phenomenology (e.g., experiential unity) with neuro-computational functions (making information globally available to different control systems) and their neural instantiation (the “global workspace” of the thalamo-cortical network). Conscious experience is, he suggests, a biological data format that, by generating a subjective reality for the organism, supports adaptive behavior that would otherwise be impossible:

It is easy to overlook the causal relevance of this first evolutionary step, the fundamental computational goal of conscious experience. It is the one necessary functional property on which everything else rests. We can simply call it “reality generation”: It allowed animals to represent explicitly the fact that something is actually the case. A transparent world-model lets you discover that something is really out there, and by integrating your portrait of the world with the subjective Now, it lets you grasp the fact that the world is present. This step opened up a new level of complexity. Thus, having a global world-model is a new way of processing information about the world in a highly integrated manner. Every conscious thought, every bodily sensation, every sound and every sight, every experience of empathy or of sharing the goals of another human being makes a different class of facts available for the adaptive, flexible, and selective form of processing that only conscious experience can provide. (p. 59)

One such fact, of critical importance, is that we come to see ourselves as thinkers and knowers who can distinguish between appearance and reality:

By consciously experiencing some elements of our tunnel as mere images or thoughts about the world, we became aware of the possibility of misrepresentation. We understood that sometimes we can be wrong, since reality is only a specific type of appearance. As evolved representational systems, we could now represent one of the most important facts about ourselves – namely, that we are representational systems. We were able to grasp the notions of truth and falsity, of knowledge and illusion. As soon as we had grasped this distinction, cultural evolution exploded, because we became ever more intelligent by systematically increasing knowledge and minimizing illusion. (p. 61)

Despite Metzinger’s confidence that the phenomenal level of representation constituted by consciousness was a major adaptive breakthrough, and is thus explicable by an evolutionary account, doubts can be raised. Evolution required simply that the neuro-computational representational functions carried out by the brain confer survival and reproductive benefits that outweighed their metabolic costs (the cognitive functions associated with consciousness use lots of glucose). What extra benefit does conscious phenomenology, which presumably supervenes on these functions, or is somehow entailed by them, provide? If consciousness is in some sense identical to higher level neuro-computations, then yes, we can say evolution selected for it, and so it’s adaptive. But if we assign phenomenal experience an ontological reality distinct from neuro-computation, as Metzinger seems to, its contribution to reproductive success becomes obscure. After all, it’s the physical world-representing, behavior-controlling system of the brain that’s engaging with the environment and conspecifics, not phenomenology. So it’s hard to see how consciousness per se is adaptive over and above the fitness conferred by its neural correlates. I raise this point simply to illustrate the difficulties of explaining consciousness – a quintessentially subjective, private, qualitative phenomenon – using concepts and terms that are objective, public and quantitative, the coin of naturalistic theories. Supernaturalistic and panpsychist theories that take consciousness as somehow basic to reality, whether in souls or in “psychons,” avoid this problem, but thus far lack any evidential support. As far as we know, consciousness is strictly associated (thus far) with biologically evolved systems; there’s no evidence that any of their constituent parts are conscious.

The self as self-model

With his theory of consciousness sketched out, although of course by no means proven, Metzinger takes a look at the self-model problem in more detail, including the question of the minimal conditions for phenomenal selfhood. This involves fascinating accounts of research into out-of-body experiences (OBEs), until recently the scientifically suspect domain of parapsychology, but now a legitimate field of study in its own right. That one’s felt location of self can shift outside the body in response to perceptual cues supports the hypothesis that phenomenal selfhood is a mutable representation, constructed by the brain. Of course committed dualists will simply argue that in OBEs the soul is out on excursion, and indeed there’s no way to categorically disprove this hypothesis. But there’s also no good scientific evidence for it, and the commitment to science and other varieties of evidence-based inquiry is taken for granted by Metzinger. Those not making this commitment will undoubtedly look elsewhere for explanations of consciousness.

As mentioned above, lucid dreams offer another route to understanding consciousness that Metzinger, a self-confessed “psychonaut,” pursues with enthusiasm. The descriptions of dreams are not to be missed, but their explanatory contribution is no less compelling. The lucid dreamer wakes up to the fact that the dream is her own brain’s doing, or put another way, her reality-model is suddenly no longer transparent, but opaque: it becomes experientially available to her as a model because she has direct, non-inferential (not just conceptual) knowledge of the fact that she’s dreaming. In lucid dreams we actually have more direct access to the underlying processing of consciousness than when waking, when we’re pretty much barred from experiencing experience as a construction.

Why is this? Metzinger’s elegant hypothesis is that it’s functionally necessary for the organism, when moving about in the world, to have an unquestionable baseline phenomenal reality constituted by transparent representations – what he calls “world zero.”  We have to have something as given, as untranscendably real, both to guide behavior from moment to moment and against which to test hypothetical scenarios of action that we rehearse in imagination. When dreaming, this constraint is relaxed since we’re not moving about, so the representational system constituted by the brain is free(er) to represent the reality-model itself as a representation. But note that the lucid dreamer doesn’t transcend the self-model in her dream; she’s still there as the subject, having the dream. Moreover, her experience is still fully and untranscendably qualitative: reds are red, blues are blue, perhaps even more so given the heightened intensity of experience often reported by lucid dreamers. This raises the intriguing question: how far can a self-maintaining representational system go in directly appreciating the fact that it simulates reality, including itself, instead of directly encountering it? Metzinger says late in the book:

The bigger picture cannot be properly reflected in the Ego Tunnel – it would dissolve the tunnel itself. Put differently, if we wanted to experience the theory as true, we could do so only by radically transforming our state of consciousness. (p. 209, emphasis added). [1]  

Naturalizing agency

The idea that the self is an online model generated by neurocomputation, not a soul or mental essence, challenges conventional notions of human agency. Not surprisingly, Metzinger concludes that the naturalistic turn in our self-understanding leaves no room for free will in the contra-causal sense of being able to transcend the mechanisms of our brains and bodies. We might experience ourselves as uncaused causers, capable of initiating causal chains de novo, and as beings that could have done otherwise in a situation as it arose, all conditions as they were, but:

The unsettling point about modern philosophy of mind and the cognitive neuroscience of will, already apparent even at this early stage, is that a final theory may contradict the way we have been subjectively experiencing ourselves for millennia. There will likely be a conflict between the scientific view of the acting self and the phenomenal narrative, the subjective story our brains tell us about what happens when we decide to act. (p. 127)

And:

From a scientific, third-person perspective, our inner experience of strong autonomy may look increasingly like what it has been all along: an appearance only.  (p. 129)

Metzinger considers the ramifications of the conflict between science and commonsense, including how it might affect notions of responsibility and punishment. Taking the scientific view would, he says, expose retribution as a “Stone Age concept” (p. 128), since retribution is ordinarily premised on the idea we could have done otherwise in a situation as it arose. For progressives such as myself, this would be a welcome development given the retributive excesses of our criminal justice system. Metzinger is not so sanguine since he suspects a false belief in contra-causal free will might be necessary to ground a fully functional notion of moral responsibility. I happen to disagree, and there’s growing anecdotal evidence that people can live perfectly responsible, meaningful lives without being deceived as to their fundamental nature. In any case this is a matter of ongoing debate among philosophers and psychologists concerned with where skepticism about free will might take us.[2]

Consciousness and autonomy

Such doubts are just one consequence of the consciousness revolution Metzinger is helping to foment with this book, a vivid and profound exercise in what he calls rational neuroanthropology. Neuroscience is rapidly reshaping our image of ourselves, and where will it all end?  After an illuminating chapter on the neurally embodied basis of empathy and social cognition, the last third of the book looks ahead: can we, and should we, build artificial conscious systems? How can we assimilate the growing understanding of our neural mechanisms and the realization that we fundamentally are such mechanisms?

Now that the neurosciences have irrevocably dissolved the Judeo-Christian image of a human being as containing an immortal spark of the divine, we are beginning to realize that they have not substituted anything that could hold society together and provide a common ground for shared moral intuitions and values. An anthropological and ethical vacuum may well follow on the heels of neuroscientific findings. (p. 213)

In the face of what he sees as a very present danger, Metzinger offers his own recommendations for how to cope with the new science of mind, demonstrating his own very humanistic, progressive sensibility. We should not, he argues, build conscious systems because in so doing we may well create new subjects of suffering. It’s to Metzinger’s credit that he draws attention to this basic ethical problem, widely unrecognized in the artificial intelligence community. Unless we can be sure that the systems we create won’t suffer, we should hold off creating them – there’s quite enough pain experienced in the world as it is.

To fill the anthropological and ethical vacuum left by the dissolution of the soul, Metzinger says we must address fundamental questions in the new field of neuroethics: What is a good or desirable state of consciousness?  How much control should we assume over our own conscious states? How much should we enhance our mental capacities, and by what means? With new understanding comes new responsibilities, since it’s very unlikely that we can block the arrival of consciousness technologies. We need a viable ethics of consciousness soon, one grounded in the facts as science reveals them.

Metzinger’s ethical anchor is the protection and enhancement of individual autonomy, despite the fact (or perhaps because of it) that our very notion of the individual is now radically revised. Even if we don’t have souls, we remain distinct persons, and each of us has a brain with an untapped potential for millions of different conscious states. From this perspective, a significant dimension of autonomy consists in the freedom to explore one’s own experiential landscape. But since we live in moral community, we can’t escape the question of whether and how much such exploration is a good thing. Should it include, as Metzinger argues it should, the safe and responsible use of psychoactive drugs? Similarly, knowing that we are bio-psycho-social constructions, should autonomy include the right to reconstruct ourselves, and what if any limits should we place on such a project?  Metzinger says “We may no longer be able to regard our own consciousness as a legitimate vehicle for our metaphysical hopes and desires.” (213)  If not, then the pursuit of autonomy could take us to transhumanism, and not just the redesign of the body, but of the mind.

More immediately, Metzinger worries about the encroachment of modern communications technology on individual consciousnesses, as advertising and entertainment place more demands on our limited reserves of attention. We can fight back by becoming more intentional in defending the personal space of subjectivity, for instance by teaching children such things as meditation, mindfulness and relaxation techniques:

…now that we know more about the critical formative phases of the human brain, shouldn’t we make use of this knowledge to maximize the autonomy of future adults? In particular, shouldn’t we introduce our children to those states of consciousness we believe to be valuable and teach them how to access and cultivate them at an early age? Education is not only about academic achievement. Recall that one positive aspect of the new image of Homo sapiens is its recognition of the vastness of our phenomenal-state space. Why not teach our children to make use of this vastness in a better way than their parents did – a way that guarantees and stabilizes their mental health, enriches their subjective lives, and grants them new insights? (p. 236)

More generally, Metzinger argues that it’s only by assimilating the naturalistic truth about who we are that we can defend individual autonomy against mass culture and its potential for manipulation. Facing the scientific facts about the self also expresses a central human value: maintaining our cognitive dignity and responsibility as knowers, what he calls “the will to clarity.” The philosophical, scientific, and moral issues raised in this book couldn’t be more demanding, but Metzinger exemplifies how we can best meet the challenge: by an unflinching commitment to rational and empirical investigation, wherever it leads, carried out within a democratic, open society of individuals informed about their true nature. Whether or not it’s completely right about the mind, The Ego Tunnel models the intellectual and ethical virtues that will be required of us, as Metzinger puts it, to "ride the tiger" of the consciousness revolution.

TWC, May, 2009

Notes