The Case Against Reality Read online

  The Case

  Against

  Reality

  Why Evolution Hid

  the Truth from Our Eyes

  DONALD

  HOFFMAN

  To Joaquin, Noemi, and Cayetano,

  I offer the red pill.

  I think that tastes, odors, colors, and so on . . .

  reside in consciousness. Hence if the living

  creature were removed, all these qualities

  would be wiped away and annihilated.

  —GALILEO GALILEI

  CONTENTS

  PREFACE

  CHAPTER ONE Mystery: The Scalpel That Split Consciousness

  CHAPTER TWO Beauty: Sirens of the Gene

  CHAPTER THREE Reality: Capers of the Unseen Sun

  CHAPTER FOUR Sensory: Fitness Beats Truth

  CHAPTER FIVE Illusory: The Bluff of a Desktop

  CHAPTER SIX Gravity: Spacetime Is Doomed

  CHAPTER SEVEN Virtuality: Inflating a Holoworld

  CHAPTER EIGHT Polychromy: Mutations of an Interface

  CHAPTER NINE Scrutiny: You Get What You Need, in Both Life and Business

  CHAPTER TEN Community: The Network of Conscious Agents

  APPENDIX Precisely: The Right to Be Wrong

  ACKNOWLEDGMENTS

  NOTES

  INDEX

  PREFACE

  Your eyes will save your life today. With their guidance, you will not tumble down stairs, leap before a speeding Maserati, grab the tail of a rattlesnake, or munch on a moldy apple.

  Why are our eyes, and all of our senses, reliable guides? Most of us have a hunch: they tell us the truth. The real world, we assume, consists of cars and stairs and other objects in space and time. They exist even if no living creature observes them. Our senses are simply a window on this objective reality. Our senses do not, we assume, show us the whole truth of objective reality. Some objects are too small or too far away. On rare occasions our senses are even wrong—artists, psychologists, cinematographers, and others can cook up illusions that fool them. But normally our senses report the truths we need to navigate safely through life.

  Why do our senses exist to reveal the truth? Again, we have a hunch: evolution. Those of our ancestors who saw reality more accurately had an advantage over those who saw it less accurately, especially in critical activities such as feeding, fighting, fleeing, and mating. As a result, they were more likely to pass on their genes, which coded for more accurate perceptions. We are the offspring of those who, in each generation, saw objective reality more accurately. Therefore, we can be confident that we see it accurately. Our hunch, in short, is that truer perceptions are fitter perceptions. Evolution weeds out untrue perceptions. That is why our perceptions are windows on objective reality.

  These hunches are wrong. On the contrary, our perceptions of snakes and apples, and even of space and time, do not reveal objective reality. The problem is not that our perceptions are wrong about this or that detail. It’s that the very language of objects in space and time is simply the wrong language to describe objective reality. This is not a hunch. It is a theorem of evolution by natural selection that wallops our hunches.

  The idea that our perceptions mislead us about objective reality, in whole or in part, has a long history. Democritus, around 400 BCE, famously claimed that our perceptions of hot, cold, sweet, bitter, and color are conventions, not reality.1 A few decades later, Plato likened our perceptions and conceptions to flickering shadows cast on the walls of a cave by an unseen reality.2 Philosophers ever since have debated the relation between perception and reality. The theory of evolution injects new rigor into this debate.

  How can our senses be useful—how can they keep us alive—if they don’t tell us the truth about objective reality? A metaphor can help our intuitions. Suppose you’re writing an email, and the icon for its file is blue, rectangular, and in the center of your desktop. Does this mean that the file itself is blue, rectangular, and in the center of your computer? Of course not. The color of the icon is not the color of the file. Files have no color. The shape and position of the icon are not the true shape and position of the file. In fact, the language of shape, position, and color cannot describe computer files.

  The purpose of a desktop interface is not to show you the “truth” of the computer—where “truth,” in this metaphor, refers to circuits, voltages, and layers of software. Rather, the purpose of an interface is to hide the “truth” and to show simple graphics that help you perform useful tasks such as crafting emails and editing photos. If you had to toggle voltages to craft an email, your friends would never hear from you.

  That is what evolution has done. It has endowed us with senses that hide the truth and display the simple icons we need to survive long enough to raise offspring. Space, as you perceive it when you look around, is just your desktop—a 3D desktop. Apples, snakes, and other physical objects are simply icons in your 3D desktop. These icons are useful, in part, because they hide the complex truth about objective reality. Your senses have evolved to give you what you need. You may want truth, but you don’t need truth. Perceiving truth would drive our species extinct. You need simple icons that show you how to act to stay alive. Perception is not a window on objective reality. It is an interface that hides objective reality behind a veil of helpful icons.

  “But,” you ask, “if that speeding Maserati is just an icon of your interface, why don’t you leap in front of it? After you die, then we’ll have proof that a car is not just an icon. It’s real and it really can kill.”

  I wouldn’t leap in front of a speeding car for the same reason I wouldn’t carelessly drag my blue icon to the trashcan. Not because I take the icon literally—the file is not blue. But I do take it seriously: if I drag the icon to the trashcan, I could lose my work.

  And that is the point. Evolution has shaped our senses to keep us alive. We have to take them seriously: if you see a speeding Maserati, don’t leap in front of it; if you see a moldy apple, don’t eat it. But it is a mistake of logic to assume that if we must take our senses seriously then we are required—or even entitled—to take them literally.

  I take my perceptions seriously, but not literally. This book is about why you should do the same, and why that matters.

  I explain why evolution hid objective reality and endowed us instead with an interface of objects in space and time. Together, we will explore how this counterintuitive idea dovetails with discoveries in physics that are equally counterintuitive. And we will examine how our interface works and how we manipulate it with makeup, marketing, and design.

  In chapter one, we confront the greatest unsolved mystery in science: your experience of the taste of dark chocolate, the smell of crushed garlic, the blare of a trumpet, the sensual feel of plush velvet, the sight of a red apple. Neuroscientists have found many correlations between such conscious experiences and brain activity. They have discovered that our consciousness can be split in half with a scalpel, and the two halves can have different personalities, with different likes, dislikes, and religious beliefs: one-half can be an atheist while the other believes in God. But despite all this data, we still have no plausible story about how brain activity might generate a conscious experience. This stunning failure suggests that we have made a false assumption. Hunting for a culprit led me to look more closely at how our senses are shaped by natural selection.

  A clear example of this shaping is our sense of beauty. We explore, in chapter two, beauty and attraction through the lens of evolution. When you glance at another person, you immediately—and unconsciously—pick up dozens of sensory clues, and run them through a sophisticated algorithm, forged by evolution, that decides one thing: reproductive potential—the likeliho
od that this person could successfully raise offspring. Your algorithm, in a fraction of a second, summarizes its complex analysis with a simple feeling—ranging from hot to not. Through the course of the chapter, we examine specific clues of beauty in the human eye. Men are attracted to women with larger eyes that have larger irises, larger pupils, slightly bluish scleras (the whites of the eyes), and distinctive limbal rings—the dark border between the iris and the sclera. What women want is more complex, and it’s a fascinating story that we will examine more closely. As we survey our sense of beauty, we absorb key concepts of evolution, learn useful tricks to spiff up portraits, and explore the logic of natural selection—including the logic that tempts us to deceive others by spiffing up.

  Many experts in evolution and neuroscience claim that our senses evolved to report truths about objective reality. Not the full spectrum of truth—just what we need to raise kids. We listen to these experts in chapter three. We hear from Francis Crick who discovered, along with James Watson, the structure of DNA. In a series of letters that Crick and I exchanged a decade before his death, he argues that our perceptions match reality, and that the sun existed before anyone saw it. We hear from David Marr, a professor at MIT who combined insights from neuroscience and artificial intelligence to transform the study of human vision. In his classic book Vision, Marr contends that we evolved to see a true description of objective reality. Marr was my doctoral advisor until his death at age thirty-five; he influenced my early ideas, and those of the entire field, on this topic. We hear from Robert Trivers, an insightful evolutionary theorist who maintains that our senses evolved to give us an accurate view of reality. Philosophers have long wondered, “Can we trust our senses to tell us truths about reality?” Many brilliant scientists answer, “Yes.”

  We look, in chapter four, at the case for “No.” We encounter a startling “Fitness-Beats-Truth” (FBT) theorem, which states that evolution by natural selection does not favor true perceptions—it routinely drives them to extinction. Instead, natural selection favors perceptions that hide the truth and guide useful action. Without equations or Greek symbols, we explore the new field of evolutionary game theory, which allows Darwin’s ideas to be transformed into precise mathematics that lead to this shocking theorem. We look at computer simulations of evolutionary games, which confirm the predictions of the FBT Theorem. We find further confirmation from simulations of genetic algorithms, in which perceptions and actions coevolve.

  The FBT Theorem tells us that the language of our perceptions—including space, time, shape, hue, saturation, brightness, texture, taste, sound, smell, and motion—cannot describe reality as it is when no one looks. It’s not simply that this or that perception is wrong. It’s that none of our perceptions, being couched in this language, could possibly be right.

  At this point, our intuitions falter: How could our senses be useful if they don’t report the truth? In chapter five, we aid our intuitions by exploring an interface metaphor. Space, time, and physical objects are not objective reality. They are simply the virtual world delivered by our senses to help us play the game of life.

  “Well,” you might say, “if you claim that space, time, and objects are not objective reality, then you are straying into the turf of physics, and physicists will be happy to set you straight.” In chapter six, we discover that eminent physicists admit that space, time, and objects are not fundamental; they’re rubbing their chins red trying to divine what might replace them. Some say that spacetime—a union of space and time required by Einstein’s theories of relativity—is doomed.3 They say that it is a hologram, made out of bits of information. Others say that reality differs from one observer to another, or that the history of the universe is not fixed but depends on what is observed now. Physics and evolution point to the same conclusion: spacetime and objects are not foundational. Something else is more fundamental, and spacetime emerges from it.

  If spacetime is not a foundational, preexisting stage on which the drama of the universe unfolds, then what is it? In chapter seven, we wade into the curious and curiouser: spacetime is just a data format—much like data structures in your mobile device—that serves to keep us alive. Our senses report fitness, and an error in this report could ruin your life. So our senses use “error-correcting codes” to detect and correct errors. Spacetime is just a format our senses use to report fitness payoffs and to correct errors in these reports. To see how this works, we play with some visual illusions, and catch ourselves in the act of correcting errors. Then we use these insights to have fun with clothing: we can manipulate the visual codes to help men and women look even better in their jeans—by making careful alterations to stitches, pockets, finishes, and embroideries.

  Then we look at color. From the refreshing blue of clear skies to the vibrant green of spring grasses, our rich world of light and color is a welcome gift, compliments of four kinds of photoreceptors in the eye. But Arabidopsis thaliana, a small weed that looks like wild mustard, has eleven kinds of photoreceptors.4 The lowly cyanobacterium, which has colonized the earth for at least two billion years, boasts twenty-seven.5 In chapter eight, we discover that color is a code for messages about fitness used by many species, a code that excels at compressing data much as you might compress a photo before texting it to a friend. Colors can trigger emotions and memories that enhance our fitness by guiding our actions. Corporations harness the power of color as a tool for branding, and will go to great lengths to defend a color as intellectual property. But as potent and evocative as color may be, “chromatures,” which are textured colors, prove far more versatile and powerful than colors alone, and for good evolutionary reasons. Chromatures can be designed to trigger specific emotions and associations. If you understand our codes for fitness, then you can intelligently hack them for your benefit.

  But evolution is not done with our sensory codes for fitness. It still experiments with novel interfaces for our enterprising species. Four percent of us are “synesthetes” who perceive a world that differs from the norm. We meet Michael Watson, who felt with his hands what he tasted with his mouth: when he tasted spearmint he felt tall, cold columns of glass; angostura bitters felt like “a scraggly basket of hanging ivy.” Each taste had its own 3D object, which he created in the moment of taste and destroyed when he stopped tasting. Some synesthetes see a unique color for each number, letter, day of the week, or month of the year—and excel at discerning colors.

  Perception may seem effortless, but in fact it requires considerable energy. Each precious calorie you burn on perception is a calorie you must find and take from its owner—perhaps a potato or an irate wildebeest. Calories can be difficult and dangerous to procure, so evolution has shaped our senses to be misers. One consequence, we discover in chapter nine, is that vision cuts corners: you see sharp detail only within a small circular window, whose radius is the width of your thumb held at arm’s length. If you close one eye and hold out your thumb, you can see just how tiny it is. We think we see the whole field of vision in great detail, but we’ve been duped: each place we look falls into that small window of sharp detail, so we mistakenly assume that we see everything in detail. Only within that small window does your sensory interface construct a detailed report of fitness payoffs. That crucial report is formatted as the shape, color, texture, motion, and identity of a physical object. You create a suitable object—your description of payoffs—with a glance. You destroy it and create another with your next glance. Your wide field of vision guides your eyes to attend where there are vital payoffs to report, and thus an object to create. We explore the rules that govern attention, how they apply in marketing and design, and how an ad can, by accident, promote a rival if it flouts the rules.

  If our senses hide reality behind an interface, then what is that reality? I don’t know. But in chapter ten we explore the idea that conscious experiences are fundamental. When you look at yourself in a mirror you see skin, hair, eyes, lips, and the expression of your face. But you know that hidden b
ehind your face is a far richer world: your dreams, fears, politics, love of music, taste in literature, love of family, and experiences of colors, smells, sounds, tastes, and touches. The face you see is just an interface. Behind it is the vibrant world of your experiences, choices, and actions.

  Perhaps the universe itself is a massive social network of conscious agents that experience, decide, and act. If so, consciousness does not arise from matter; this is a big claim that we will explore in detail. Instead, matter and spacetime arise from consciousness—as a perceptual interface.

  This book offers you the red pill.6 If you can accept that the technology of virtual reality will one day create for you a compelling experience that is nothing like your experience when you take off the headset, then why be so certain that, when you remove the headset, you’re seeing reality as it is? The purpose of this book is to help you take off the next headset, the one you didn’t know you were wearing all along.

  The Case Against Reality

  CHAPTER ONE

  Mystery

  The Scalpel That Split Consciousness

  “How it is that anything so remarkable as a state of consciousness comes about as a result of irritating nervous tissue, is just as unaccountable as the appearance of the Djinn, when Aladdin rubbed his lamp.”

  —THOMAS HUXLEY, THE ELEMENTS OF PHYSIOLOGY AND HYGIENE

  “ ‘A motion became a feeling!’—no phrase that our lips can frame is so devoid of apprehensible meaning.”

  —WILLIAM JAMES, THE PRINCIPLES OF PSYCHOLOGY

  In February of 1962, Joseph Bogen and Philip Vogel sliced in half the brain of Bill Jenkins—intentionally, methodically, and with careful premeditation. Jenkins, then in his late forties, recovered and went on to enjoy a quality of life that had eluded him for years. In the decade that followed, Bogen and Vogel split brain after brain in California, earning them the epithet “the West Coast butchers.”1