Table of Contents Title Page Dedication Epigraph Acknowledgements Introduction PART ONE - THE CONSCIOUSNESS PROBLEM ONE - THE APPEARANCE OF A WORLD TWO - A TOUR OF THE TUNNEL THE ONE-WORLD PROBLEM: THE UNITY OF CONSCIOUSNESS THE NOW PROBLEM: A LIVED MOMENT EMERGES THE REALITY PROBLEM: HOW YOU WERE BORN AS A NAIVE REALIST THE INEFFABILITY PROBLEM: WHAT WE WILL NEVER BE ABLE TO TALK ABOUT THE EVOLUTION PROBLEM: COULDN’T ALL OF THIS HAVE HAPPENED IN THE DARK? THE WHO PROBLEM: WHAT IS THE ENTITY THAT HAS CONSCIOUS EXPERIENCE? CHAPTER TWO APPENDIX THE UNITY OF CONSCIOUSNESS: A CONVERSATION WITH WOLF SINGER PART TWO - IDEAS AND DISCOVERIES THREE - OUT OF THE BODY AND INTO THE MIND THE OUT-OF-BODY EXPERIENCE VIRTUAL OUT-OF-BODY EXPERIENCES THE ESSENCE OF SELFHOOD WE LIVE IN A VIRTUAL WORLD PHANTOM LIMBS FOUR - FROM OWNERSHIP TO AGENCY TO FREE WILL THE ALIEN HAND HALLUCINATING AGENCY HOW FREE ARE WE? FIVE - PHILOSOPHICAL PSYCHONAUTICS What Can We Learn from Lucid Dreaming? LUCID DREAMING CHAPTER FIVE APPENDIX DREAMING: A CONVERSATION WITH ALLAN HOBSON SIX - THE EMPATHIC EGO SOCIAL NEUROSCIENCE: CANONICAL NEURONS AND MIRROR NEURONS CHAPTER SIX APPENDIX THE SHARED MANIFOLD: A CONVERSATION WITH VITTORIO GALLE SE PART THREE - THE CONSCIOUSNESS REVOLUTION SEVEN - ARTIFICIAL EGO MACHINES HOW TO BUILD AN ARTIFICIAL CONSCIOUS SUBJECT AND WHY WE SHOULDN’T DO IT BLISS MACHINES: IS CONSCIOUS EXPERIENCE A GOOD IN ITSELF? A CONVERSATION WITH THE FIRST POSTBIOTIC PHILOSOPHER EIGHT - CONSCIOUSNESS TECHNOLOGIES AND THE IMAGE OF HUMANKIND A NEW IMAGE OF HOMO SAPIENS THE THIRD PHASE OF THE REVOLUTION ALTERED STATES NINE - A NEW KIND OF ETHICS WHAT IS A GOOD STATE OF CONSCIOUSNESS? RIDING THE TIGER: A NEW CULTURAL CONTEXT NOTES INDEX Copyright Page To Anja and my family Any theory that makes progress is bound to be initially counterintuitive —DANIEL C DENNETT, The Intentional Stance (Cambridge, MA 1987, p 6) He [Ludwig Wittgenstein] once greeted me with the question: “Why people say that it was natural to think that the sun went round the earth rather than that the earth turned on its axis?” I replied: “I suppose, because it looked as if the sun went round the earth.” “Well,” he asked, “what would it have looked like if it had looked as if the earth turned on its axis?” —ELIZABETH ANSCOMBE, An Introduction to Wittgenstein’s Tractatus (London 1959, p 151) ACKNOWLEDGMENTS This book has not been written for philosophers or scientists Instead, it is my first attempt to introduce a wider public to what I think are the truly important issues in consciousness research today The selection of relevant philosophical issues and new empirical insights is entirely my own— and of course hopelessly incomplete and necessarily superficial But I hope this book will give interested lay readers a realistic view of the picture of self-consciousness and the human mind now emerging—and of the accompanying challenges all of us will have to face in the future Of the many people who have supported me in this project, my first thanks go to Jennifer Windt, who has spent countless hours helping me with the English version I have learned a great deal from her It is difficult to write a nonacademic book in a language other than your own, and if I have at least partly succeeded, it is due to her accuracy, conscientiousness, and reliability I then found a superbly professional editor in Sara Lippincott I am deeply indebted to both of them Among the many colleagues who have supported me, I am particularly grateful to Susan Blackmore, Olaf Blanke, Peter Brugger, Daniel Dennett, Vittorio Gallese, Allan Hobson, Victor Lamme, Bigna Lenggenhager, Antoine Lutz, Angelo Maravita, Wolf Singer, Tej Tadi, and Giulio Tononi This work was in part supported by the COGITO Foundation (Switzerland), the DISCOS Project (“Disorders and Coherence of the Embodied Self,” an EU Marie Curie Research Training Network), and a Fellowship at Europe’s best Institute for Advanced Research, the Wissenschaftskolleg zu Berlin Thomas Metzinger January 2009 INTRODUCTION In this book, I will try to convince you that there is no such thing as a self Contrary to what most people believe, nobody has ever been or had a self But it is not just that the modern philosophy of mind and cognitive neuroscience together are about to shatter the myth of the self It has now become clear that we will never solve the philosophical puzzle of consciousness—that is, how it can arise in the brain, which is a purely physical object—if we don’t come to terms with this simple proposition: that to the best of our current knowledge there is no thing, no indivisible entity, that is us, neither in the brain nor in some metaphysical realm beyond this world So when we speak of conscious experience as a subjective phenomenon, what is the entity having these experiences? There are other important issues in the quest to probe our inner nature—new, exciting theories about emotions, empathy, dreaming, rationality, recent discoveries about free will and the conscious control of our actions, even about machine consciousness—and they are all valuable, as the building blocks of a deeper understanding of ourselves I will touch on many of them in this book What we currently lack, however, is the big picture—a more general framework we can work with The new mind sciences have generated a flood of relevant data but no model that can, at least in principle, integrate all these data There is one central question we have to confront head on: Why is there always someone having the experience? Who is the feeler of your feelings and the dreamer of your dreams? Who is the agent doing the doing, and what is the entity thinking your thoughts? Why is your conscious reality your conscious reality? This is the heart of the mystery If we want not just the building blocks but a unified whole, these are the essential questions There is a new story, a provocative and perhaps shocking one, to be told about this mystery: It is the story of the Ego Tunnel The person telling you this story is a philosopher, but one who has closely cooperated with neuroscientists, cognitive scientists, and researchers in artificial intelligence for many years Unlike many of my philosopher colleagues, I think that empirical data are often directly relevant to philosophical issues and that a considerable part of academic philosophy has ignored such data for much too long The best philosophers in the field clearly are analytical philosophers, those in the tradition of Gottlob Frege and Ludwig Wittgenstein: In the past fifty years, the strongest contributions have come from analytical philosophers of mind However, a second aspect has been neglected too much: phenomenology, the fine-grained and careful description of inner experience as such In particular, altered states of consciousness (such as meditation, lucid dreaming, or out-of-body experiences) and psychiatric syndromes (such as schizophrenia or Cotard’s syndrome, in which patients may actually believe they not exist) should not be philosophical taboo zones Quite the contrary: If we pay more attention to the wealth and the depth of conscious experience, if we are not afraid to take consciousness seriously in all of its subtle variations and borderline cases, then we may discover exactly those conceptual insights we need for the big picture In the chapters that follow, I will lead you through the ongoing Consciousness Revolution Chapters and introduce basic ideas of consciousness research and the inner landscape of the Ego Tunnel Chapter examines out-of-body experiences, virtual bodies, and phantom limbs Chapter deals with ownership, agency, and free will; chapter with dreams and lucid dreaming; chapter with empathy and mirror neurons; and chapter with artificial consciousness and the possibility of postbiotic Ego Machines All these considerations will help us to further map out the Ego Tunnel The two final chapters address some of the consequences of these new scientific insights into the nature of the conscious mind-brain: the ethical challenges they pose and the social and cultural changes they may produce (and sooner than we think), given the naturalistic turn in the image of humankind I close by arguing that ultimately we will need a new “ethics of consciousness.” If we arrive at a comprehensive theory of consciousness, and if we develop ever more sophisticated tools to alter the contents of subjective experience, we will have to think hard about what a good state of consciousness is We urgently need fresh and convincing answers to questions like the following: Which states of consciousness we want our children to have? Which states of consciousness we want to foster, and which we want to ban on ethical grounds? Which states of consciousness can we inflict upon animals, or upon machines? Obviously, I cannot provide definitive answers to such questions; instead, the concluding chapters are meant to draw attention to the important new discipline of neuroethics while at the same time widening our perspective THE PHENOMENAL SELF-MODEL Before I introduce the Ego Tunnel, the central metaphor that will guide the discussion from here onward, it will be helpful to consider an experiment that strongly suggests the purely experiential nature of the self In 1998, University of Pittsburgh psychiatrists Matthew Botvinick and Jonathan Cohen conducted a now-classic experiment in which healthy subjects experienced an artificial limb as part of their own body The subjects observed a rubber hand lying on the desk in front of them, with their own corresponding hand concealed from their view by a screen The visible rubber hand and the subject’s unseen hand were then synchronously stroked with a probe The experiment is easy to replicate: After a certain time (sixty to ninety seconds, in my case), the famous rubber-hand illusion emerges Suddenly, you experience the rubber hand as your own, and you feel the repeated strokes in this rubber hand Moreover, you feel a full-blown “virtual arm”—that is, a connection from your shoulder to the fake hand on the table in front of you The most interesting feature I noticed when I underwent this experiment was the strange tingling sensation in my shoulder shortly before the onset of the illusion—shortly before, as it were, my “soul arm” or “astral limb” slipped from the invisible physical arm into the rubber hand Of course, there is no such thing as a ghostly arm, and probably no such thing as an astral body, either What you feel in the rubber-hand illusion is what I call the content of the phenomenal self-model (PSM)—the conscious model of the organism as a whole that is activated by the brain (“Phenomenal” is used here, and throughout, in the philosophical sense, as pertaining to what is known purely experientially, through the way in which things subjectively appear to you.) The content of the PSM is the Ego Figure 1: The rubber-hand illusion A healthy subject experiences an artificial limb as part of her own body The subject observes a facsimile of a human hand while her own hand is concealed (gray square) Both the artificial rubber hand and the invisible hand are stroked repeatedly and synchronously with a probe The light areas around the hand and the dark areas in the index finger indicate the respective tactile and visual receptive fields for neurons in the premotor cortex The illustration on the right shows the subject’s illusion as the felt strokes are aligned with the seen contribution to cognitive neuroscience eliminative phenomenalism emergence of the self-conscious mind essence of selfhood evolutionary function of dreaming extent of free will mind-body problem neurobiological solutions for philosophical questions out-of-body phenomenology perception versus action postbiotic philosopher simulation social cognition understanding and neutralizing suffering PiHKAL: A Chemical Love Story (Shulgin and Shulgin) Pixel perception Plastic nature of dream state Plato Point of view experiential Now of an artificial Ego machine second-person perspective See also First-person perspective; Third-person perspective Pöppel, Ernst Popper, Karl R Postbiotic systems Practical intentionality Prefrontal lobotomy Pre-lucid dreams Presence Presence journal Present moment Primary consciousness Primates See Animal consciousness; Monkeys Priority principle of will Prophetic meaning of dreams Proprioception Psilocybin Psychiatric disorders Alien Hand syndrome chemically induced psychosis Cotard’s syndrome out-of-body experiences and RBD disorder schizophrenia subjectivity of conscious experience unity of consciousness Psychoactive substances Psychological evolution Psychological moment Psychosis, chemically induced Putnam, Hilary Qualia Raffman, Diana Rainbow body Ramachandran, Vilayanur S Ray of attention RBD disorder Realism, naive Reality conscious and physical consciousness as an evolving biological phenomenon evolution of consciousness lucid dreaming and the nature of OBEs as models of Reality checks Reality generation Reality Problem Reality tunnel Reciprocal interaction model Recurrent connections Recursion Reductionism Religious and spiritual experience and intellectual honesty as different chemically induced creating ethereal body (OBE) neuroanthropology and the future of Homo sapiens selflessness of REM sleep Representation body image and sense of ownership evolution of consciousness goal representations metarepresentation of conscious states of the world of time out-of-body experiences phantom limbs and body image transparency of phenomenal representations Representational content La reproduction interdite (painting) Republic (Plato) Responsibility, social Resurrection body Retribution Revonsuo, Antti Ritalin Rizzolatti, Giacomo Robot arm Robot society, free will and Rubber-hand illusion Ruhnau, Eva Ryle, Gilbert Schizophrenia agency and sense of self Alien Hand syndrome OBEs and Schizotypy Science, consciousness Science fiction Scotoma, artificial Secondary consciousness Second-person perspective Self The Self and Its Brain (Popper and Eccles) Self-conscious minds Selfhood artificial Ego machine essence of out-of-body experiences rubber-hand illusion Self-identification Self-knowledge, philosophical ideal of Self-localization Self-model artificial Ego machine (figs.) as physical process conscious experience as interface ethics of lie detection lucid dreaming moral development out-of-body experiences phantom limbs social neuroscience See also Phenomenal self-model Self-model theory of subjectivity Self-modeling machines Self-representation: canonical neurons Sense of effort Sense of ownership See Ownership, sense of Sensory experience during dreaming during lucid dreaming experiencing and observing pain of artificial Ego machines virtual organs See also Auditory perception; Olfactory perception; Tactile perception; Visual perception Sensory integration, body image and Seth, Anil K Shadow metaphor Shadows in out-of-body experiences Shanks, Roger Shared manifold Shattered worlds Short-term memory Shulgin, Alexander Shulgin, Ann Simulation, embodied Simultaneity of information processing Singer, Wolf Slave robot Sleep See Dreaming; Lucid dreaming; Out-of-body experiences Sleep-wake cycle Smeared present Smell, sense of Social cognition mirror-neuron systems phenomenological aspects of shared manifold theory of mind Social correlates of the phenomenal Ego Social institution, free will as Social neuroscience Software Solipsism Solms, Mark Somatoform dissociation Soul concept Sound See Auditory perception Space of attentional agency Specious present Spinoza, Baruch Starfish, artificial(figs.) Stickgold, Robert Stroke patients, dreaming and Students, OBEs in Subjective experience biological nature of Bliss Machine color perception discriminating and identifying perceptual values dreaming experiential Now first-person perspective investigating the science of mirror-neuron systems naive realism neuronal activity associated with phenomenal content of mental representation postbiotic and biological self-model theory of Who Problem Subjectivity, self-model of Subpersonal brain Subpersonal information processing Subsymbolic information processing Subtle body Suffering Sufism Supracelestial body Synchrony Synthetic phenomenology Tactile perception integrating touch and sight in tool use mirror-neuron system out-of-body experiences rubber-hand illusion transparency of phenomenal representations virtual organs Taoism Task acquisition Taste: blindness and dreaming Telepresence Television Temporal domain evolution of consciousness Now problem ”self-less” forms of conscious experience transparency of phenomenal representations Temporal gestalt Temporal-lobe theory of religious experience Temporo-parietal junction (TPJ) Theoretical entities Theory of consciousness classical theories Evolution Problem Ineffability Problem naive realism Now problem One-World Problem Reality Problem Who Problem Theory of mind Third-person perspective appearance of free will Ineffability Problem out-of-body experiences subjectivity of conscious experience visual memory Tholey, Paul TiHKAL: The Continuation (Shulgin) Time: experiential Now Time travel Tononi, Giulio Tool use Total flight simulator Transparency artificial Ego machine Bliss Machine conscious experience of intention emergency of self ethics of lie detection evolution of consciousness naive realism of postbiotic systems of the self-model transparent phenomenal states Trans-tunnel communication Trethowan, William Truth Tryptamines Tunnel concept See Conscious experience Turing, Alan M 2001: A Space Odyssey (movie) Uncommon Psychiatric Syndromes (Enoch and Trethowan) Unconscious self and processes dreaming extent of free will motor vocabulary synchrony Unity of consciousness Vajrayana van Eeden, Frederick Vestibular information Vestibulo-motor sensations Video games Violent dreams Virtual body Virtual interface Virtual limbs Virtual organs Virtual out-of-body experiences Virtual reality dream state Ego Tunnel interface for phantom limbs virtual out-of-body experiences Virtual window of presence Virtual world Visual memory Visual perception apperceptive agnosia blindness and dreaming canonical neurons dreaming essence of self Ineffability Problem integrating touch and sight in tool use optical illusions out-of-body experiences recurrent connections rubber-hand illusion transparency of phenomenal representations Vocabulary, motor Waelti, Ernst Waking Wegner, Daniel M Wernicke’s area Wheatley, Thalia Who Problem Working memory World-binding function World-zero hypothesis Zombies Zykov, Victor Copyright © 2009 by Thomas Metzinger Published by Basic Books, A Member of the Perseus Books Group All rights reserved No part of this book may be reproduced in any manner whatsoever without written permission except in the case of brief quotations embodied in critical articles and reviews For information, address Basic Books, 387 Park Avenue South, New York, NY 10016-8810 Books published by Basic Books are available at special discounts for bulk purchases in the United States by corporations, institutions, and other organizations For more information, please contact the Special Markets Department at the Perseus Books Group, 2300 Chestnut Street, Suite 200, Philadelphia, PA 19103, or call (800) 810-4145, ext 5000, or e-mail special.markets@perseusbooks.com Set in 10.75 point Warnock Pro by the Perseus Books Group Library of Congress Cataloging-in-Publication Data Metzinger, Thomas, 1958The ego tunnel : the science of the mind and the myth of the self / Thomas Metzinger p cm Includes bibliographical references and index eISBN : 978-0-465-04567-9 Consciousness I Title BF311.M47 2009 126—dc22 2008044399 ... All they have ever seen of themselves and of one another are the shadows cast on the opposite wall of the cave by the fire burning behind them They believe the shadows to be real objects The. .. hierarchy: the letters into the page, the page into the book, the hand holding the book into your bodily self, and the self sitting in a chair in the room and understanding the words We want a unity of. .. further map out the Ego Tunnel The two final chapters address some of the consequences of these new scientific insights into the nature of the conscious mind- brain: the ethical challenges they