The Mind’s I: Fantasies and Reflections on Self and Soul

24 Thomas Nagel What Is It Like to Be a Bat?[36]

Consciousness is what makes the mind-body problem really intractable. Perhaps that is why current discussions of the problem give it little attention or get it obviously wrong. The recent wave of reductionist euphoria has produced several analyses of mental phenomena and mental concepts designed to explain the possibility of some variety of materialism, psychophysical identification, or reduction.[37] But the problems dealt with are those common to this type of reduction and other types, and what makes the mind-body problem unique, and unlike the water-H₂0 problem or the Turing machine-IBM machine problem or the lightning-electrical discharge problem or the gene-DNA problem or the oak tree-hydrocarbon problem, is ignored.

Every reductionist has his favorite analogy from modern science. It is most unlikely that any of these unrelated examples of successful reduction will shed light on the relation of mind to brain. But philosophers share the general human weakness for explanations of what is incomprehensible in terms suited for what is familiar and well understood, though entirely different. This has led to the acceptance of implausible accounts of the mental largely because they would permit familiar kinds of reduction. I shall try to explain why the usual examples do not help us to understand the relation between mind and body—why, indeed, we have at present no conception of what an explanation of the physical nature of a mental phenomenon would be. Without consciousness the mind-body problem would be much less interesting. With consciousness seems hopeless. The most important and characteristic feature of conscious mental phenomena is very poorly understood. Most reductionist theories do not even try to explain it. And careful examination will show that no currently available concept of reduction is applicable to it. Perhaps a new theoretical form can be devised for the purpose, but such a solution, if it exists, lies in the distant intellectual future.

Conscious experience is a widespread phenomenon. It occurs a many levels of animal life, though we cannot be sure of its presence in the simpler organisms, and it is very difficult to say in general what provides evidence of it. (Some extremists have been prepared to deny it even of mammals other than man.) No doubt it occurs in countless forms totally unimaginable to us, on other planets in other solar systems throughout the universe. But no matter how the form may vary, the fact that an organism has conscious experience at all means, basically, that there is something it is like to be that organism. There may be further implications about the form of the experience; there may even (though I doubt it) be implications about the behavior of the organism. But fundamentally an organism has conscious mental states if and only if there is something that it is like to be that organism—something it is like for the organism.

We may call this the subjective character of experience. It is not captured by any of the familiar, recently devised reductive analyses of the mental, for all of them are logically compatible with its absence. It is no analyzable in terms of any explanatory system of functional states, or intentional states, since these could be ascribed to robots or automata that behaved like people though they experienced nothing.[38] It is no analyzable in terms of the causal role of experiences in relation to typical human behavior—for similar reasons I do not deny that conscious mental states and events cause behavior, nor that they may be given functional characterizations. I deny only that this kind of thing exhausts their analysis. Any reductionist program has to be based on an analysis of what is to be reduced. If the analysis leaves something out, the problem will be falsely posed. It is useless to base the defense of materialism on any analysis of mental phenomena that fails to deal explicitly with their subjective character. For there is no reason to suppose that a reduction which seems plausible when no attempt is made to account for consciousness can be extended to include consciousness. Without some idea, therefore, of what the subjective character of experience is, we cannot know what is required of physicalist theory.

While an account of the physical basis of mind must explain many things, this appears to be the most difficult. It is impossible to exclude the phenomenological features of experience from a reduction in the same way that one excludes the phenomenal features of an ordinary substance from a physical or chemical reduction of it—namely, by explaining them as effects on the minds of human observers (cf. Rorty 1965). If physicalism is to be defended, the phenomenological features must themselves be given a physical account. But when we examine their subjective character it seems that such a result is impossible. The reason is that every subjective phenomenon is essentially connected with a single point of view, and it seems inevitable that an objective, physical theory will abandon that point of view.

Let me first try to state the issue somewhat more fully than by referring to the relation between the subjective and the objective, or between the pour soi and the en soi. This is far from easy. Facts about what it is like to be an X are very peculiar, so peculiar that some may be inclined to doubt their reality, or the significance of claims about them. To illustrate the connection between subjectivity and a point of view, and to make evident the importance of subjective features, it will help to explore the matter in relation to an example that brings out clearly the divergence between the two types of conception, subjective and objective.

I assume we all believe that bats have experience. After all, they are mammals, and there is no more doubt that they have experience than that mice or pigeons or whales have experience. I have chosen bats instead of wasps or flounders because if one travels too far down the phylogenetic tree, people gradually shed their faith that there is experience there at all. Bats, although more closely related to us than those other species, nevertheless present a range of activity and a sensory apparatus so different from ours that the problem I want to pose is exceptionally vivid (though it certainly could be raised with other species). Even without the benefit of philosophical reflection, anyone who has spent some time in an enclosed space with an excited bat knows what it is to encounter a fundamentally alien form of life.

I have said that the essence of the belief that bats have experience is that there is something that it is like to be a bat. Now we know that most bats (the microchiroptera, to be precise) perceive the external world primarily by sonar, or echolocation, detecting the reflections, from objects within range, of their own rapid, subtly modulated, high-frequency shrieks. Their brains are designed to correlate the outgoing impulse with the subsequent echoes, and the information thus acquired enables bats to make precise discriminations of distance, size, shape, motion, and texture comparable to those we make by vision. But bat sonar, though clearly a form of perception, is not similar in its operation to any sense that we possess, and there is no reason to suppose that it is subjectively like anything we can experience or imagine. This appears to create difficulties for the notion of what it is like to be a bat. We must consider, whether any method will permit us to extrapolate to the inner life of the bat from our own case,[39] and if not, what alternative methods there may be for understanding the notion.

Our own experience provides the basic material for our imagination whose range is therefore limited. It will not help to try to imagine that one has webbing on one’s arms, which enables one to fly around at dusk and dawn catching insects in one’s mouth; that one has very poor vision, and perceives the surrounding world by a system of reflected high-frequency sound signals; and that one spends the day hanging upside down by one’s feet in an attic. Insofar as I can imagine this (which is not very far), it tells me only what it would be like for me to behave as a bat behaves. But that is not the question. I want to know what it is like for a bat to be a bat. Yet if I try to imagine this, I am restricted to the resources of my own mind, and those resources are inadequate to the task. I cannot perform it either by imagining additions to my present experience, or by imagining segments gradually subtracted from it, or by imagining some combination of additions, subtractions, and modifications.

To the extent that I could look and behave like a wasp or a bat without changing my fundamental structure, my experiences would not be anything like the experiences of those animals. On the other hand, it is doubtful that any meaning can be attached to the supposition that I should possess the internal neurophysiological constitution of a bat. Even if I could by gradual degrees be transformed into a bat, nothing in my present constitution enables me to imagine what the experiences of such a future stage of myself thus metamorphosed would be like. The best evidence would come from the experiences of bats, if we only knew what they were like.

So if extrapolation from our own case is involved in the idea of what it is like to be a bat, the extrapolation must be incompletable. We cannot form more than a schematic conception of what it is like. For example, we may ascribe general types of experience on the basis of the animal’s structure and behavior. Thus we describe bat sonar as a form of three-dimensional forward perception; we believe that bats feel some versions of pain, fear, hunger, and lust, and that they have other, more familiar types of perception besides sonar. But we believe that these experiences also have in each case a specific subjective character, which it is beyond our ability to conceive. And if there is conscious life elsewhere in the universe, it is likely that some of it will not be describable even in the most general experiential terms available to us.[40] (The problem is not confined to exotic cases, however, for it exists between one person and another. The subjective character of the experience of a person deaf and blind from birth is not accessible to me, for example, nor presumably is mine to him. This does not prevent us each from believing that the other’s experience has such a subjective character.)

If anyone is inclined to deny that we can believe in the existence of facts like this whose exact nature we cannot possibly conceive, he should reflect that in contemplating the bats we are in much the same position that intelligent bats or Martians[41] would occupy if they tried to form a conception of what it was like to be us. The structure of their own minds might make it impossible for them to succeed, but we know they would be wrong to conclude that there is not anything precise that it is like to be us: that only certain general types of mental state could be ascribed to us (perhaps perception and appetite would be concepts common to us both; perhaps not). We know they would be wrong to draw such a skeptical conclusion because we know what it is like to be us. And we know that while it includes an enormous amount of variation and complexity, and while we do not possess the vocabulary to describe it adequately, its subjective character is highly specific, and in some respects describable in terms that can be understood only by creatures like us. The fact that we cannot expect ever to accommodate in our language a detailed description of Martian or bat phenomenology should not lead us to dismiss as meaningless the claim that bats and Martians have experiences fully comparable in richness of detail to our own. It would be fine if someone were to develop concepts and a theory that enabled us to think about those things; but such an understanding may be permanently denied to us by the limits of our nature. And to deny the reality or logical significance of what we can never describe or understand is the crudest form of cognitive dissonance.

This brings us to the edge of a topic that requires much more discussion than I can give it here: namely, the relation between facts on the one hand and conceptual schemes or systems of representation on the other. My realism about the subjective domain in all its forms implies a belief in the existence of facts beyond the reach of human concepts. Certainly it is possible for a human being to believe that there are facts which humans never will possess the requisite concepts to represent or comprehend. Indeed, it would be foolish to doubt this, given the finiteness of humanity’s expectations. After all, there would have been transfinite numbers even if everyone had been wiped out by the Black Death before Cantor discovered them. But one might also believe that there are facts which could not ever be represented or comprehended by human beings, even if the species lasted forever—simply because our structure does not permit us to operate with concepts of the requisite type. This impossibility might even be observed by other beings, but it is not clear that the existence of such beings, or the possibility of their existence, is a precondition of the significance of the hypothesis that there are humanly inaccessible facts. (After all, the nature of beings with access to humanly inaccessible facts is presumably itself a humanly inaccessible fact.) Reflection on what it is like to be a bat seems to lead us, therefore, to the conclusion that there are facts that do not consist in the truth of propositions expressible in a human language. We can be compelled to recognize the existence of such facts without being able to state or comprehend them.

I shall not pursue this subject, however. Its bearing on the topic before us (namely, the mind-body problem) is that it enables us to make a general observation about the subjective character of experience. Whatever may be the status of facts about what it is like to be a human being, or a bat, or a Martian, these appear to be facts that embody a particular point of view.

I am not adverting here to the alleged privacy of experience to its possessor. The point of view in question is not one accessible only to a single individual. Rather it is a type. It is often possible to take up a point of view other than one’s own, so the comprehension of such facts is not limited to one’s own case. There is a sense in which phenomenological facts are perfectly objective: One person can know or say of another what the quality of the other’s experience is. They are subjective, however, in the sense that even this objective ascription of experience is possible only for someone sufficiently similar to the object of ascription to be able to adopt his point of view—to understand the ascription in the first person as well as in the third, so to speak. The more different from oneself the other experiencer is, the less success one can expect with this enterprise. In our own case we occupy the relevant point of view, but we will have as much difficulty understanding our own experience properly if we approach it from another point of view as we would if we tried to understand the experience of another species without taking up its point of view.[42]

This bears directly on the mind-body problem. For if the facts of experience—facts about what it is like for the experiencing organism—are accessible only from one point of view, then it is a mystery how the true character of experiences could be revealed in the physical operation of that organism. The latter is a domain of objective facts par excellence the kind that can be observed and understood from many points of view and by individuals with differing perceptual systems. There are no comparable imaginative obstacles to the acquisition of knowledge about bat neurophysiology by human scientists, and intelligent bats or Martians might learn more about the human brain than we ever will.

This is not by itself an argument against reduction. A Martian scientist with no understanding of visual perception could understand the rainbow, or lightning, or clouds as physical phenomena, though he would never be able to understand the human concepts of rainbow, lightning, or cloud, or the place these things occupy in our phenomenal world. The objective nature of the things picked out by these concepts could be apprehended by him because, although the concepts themselves are connected with a particular point of view and a particular visual phenomenology, the things apprehended from that point of view are not: they are observable from the point of view but external to it; hence they can be comprehended from other points of view also, either by the same organisms or by others. Lightning has an objective character that is not exhausted by its visual appearance, and this can be investigated by a Martian without vision. To be precise, it has a more objective character than is revealed in its visual appearance. In speaking of the move from subjective to objective characterization, I wish to remain noncommittal about the existence of an end point, the completely objective intrinsic nature of the thing, which one might or might not be able to reach. It may be more accurate to think of objectivity as a direction in which the understanding can travel. And in understanding a phenomenon like lightning it is legitimate to go as far away as one can from a strictly human viewpoint.[43]

In the case of experience, on the other hand, the connection with particular point of view seems much closer. It is difficult to understand what could be meant by the objective character of an experience, apart from the particular point of view from which its subject apprehends it. After all, what would be left of what it was like to be a bat if one removed the viewpoint of the bat? But if experience does not have, in addition to its subjective character, an objective nature that can be apprehended from many different points of view, then how can it be supposed that a Martian investigating my brain might be observing physical processes which were my mental processes (as he might observe physical processes which were bolts of lightning), only from a different point of view? How, for that matter, could a human physiologist observe them from another point of view?[44]

We appear to be faced with a general difficulty about psychophysical reduction. In other areas the process of reduction is a move in the direction of greater objectivity, toward a more accurate view of the real nature of things. This is accomplished by reducing our dependence on individual or species-specific points of view toward the object of investigation. We describe it not in terms of the impressions it makes on our senses, but in terms of its more general effects and of properties detectable by means other than the human senses. The less it depends on a specifically human viewpoint, the more objective is our description. It is possible to follow this path because although the concepts and ideas we employ in thinking about the external world are initially applied from a point of view that involves our perceptual apparatus, they are used by us to refer to things beyond themselves—toward which we have the phenomenal point of view. Therefore we can abandon it in favor of another, and still be thinking about the same things.

Experience itself, however, does not seem to fit the pattern. The idea of moving from appearance to reality seems to make no sense here. What is the analogue in this case to pursuing a more objective understanding of the same phenomena by abandoning the initial subjective viewpoint toward them in favor of another that is more objective but concerns the same thing? Certainly it appears unlikely that we will get closer to the real nature of human experience by leaving behind the particularity of our human point of view and striving for a description in terms accessible to beings that could not imagine what it was like to be us. If the subjective character of experience is fully comprehensible only from one point of view, then any shift to greater objectivity—that is, less attachment to a specific viewpoint—does not take us nearer to the real nature of the phenomenon: It takes us farther away from it.

In a sense, the seeds of this objection to the reducibility of experience are already detectable in successful cases of reduction; for in discovering sound to be, in reality, a wave phenomenon in air or other media, we leave behind one viewpoint to take up another, and the auditory, human or animal viewpoint that we leave behind remains unreduced. Members of radically different species may both understand the same physical events in objective terms, and this does not require that they understand the phenomenal forms in which those events appear to the senses of members of the other species. Thus it is a condition of their referring to a common reality that their more particular viewpoints are not part of the common reality that they both apprehend. The reduction can succeed only if the species-specific viewpoint is omitted from what is to be reduced.

But while we are right to leave this point of view aside in seeking a fuller understanding of the external world, we cannot ignore it permanently, since it is the essence of the internal world, and not merely a point of view on it. Most of the neobehaviorism of recent philosophical psychology results from the effort to substitute an objective concept of mind for the real thing, in order to have nothing left over which cannot be reduced. If we acknowledge that a physical theory of mind must account for the subjective character of experience, we must admit that no presently available conception gives us a clue how this could be done. The problem is unique. If mental processes are indeed physical processes, then there is something it is like, intrinsically,[45] to undergo certain physical processes. What it is for such a thing to be the case remains a mystery.

What moral should be drawn from these reflections, and what should be done next? It would be a mistake to conclude that physicalism must be false. Nothing is proved by the inadequacy of physicalist hypothesis that assume a faulty objective analysis of mind. It would be truer to say that physicalism is a position we cannot understand because we do not at present have any conception of how it might be true. Per haps it will be thought unreasonable to require such a conception as a condition of understanding. After all, it might be said, the meaning of physicalism is clear enough: mental states are states of the body, mental events are physical events. We do not know which physical states and events they are, but that should not prevent us from undo standing the hypothesis. What could be clearer than the words “is” and “are”?

But I believe it is precisely this apparent clarity of the word “is” that is deceptive. Usually, when we are told that X is Y we know how it is supposed to be true, but that depends on a conceptual or theoretical background and is not conveyed by the “is” alone. We know how both “X” and “Y” refer, and the kinds of things to which they refer, and we, have a rough idea how the two referential paths might converge on a single thing, be it an object, a person, a process, an event or whatever. But when the two terms of the identification are very disparate it may not be so clear how it could be true. We may not have even a rough idea of how the two referential paths could converge, or what kind of things they might converge on, and a theoretical framework may have to be supplied to enable us to understand this. Without the framework, an air of mysticism surrounds the identification.

This explains the magical flavor of popular presentations of fundamental scientific discoveries, given out as propositions to which one must subscribe without really understanding them. For example, people are now told at an early age that all matter is really energy. But despite the fact that they know what “is” means, most of them never form a conception of what makes this claim true, because they lack the theoretical background.

At the present time the status of physicalism is similar to that which the hypothesis that matter is energy would have had if uttered by a pre-Socratic philosopher. We do not have the beginnings of a conception of how it might be true. In order to understand the hypothesis that a mental event is a physical event, we require more than an understanding of the word “is.” The idea of how a mental and a physical term might refer to the same thing is lacking, and the usual analogies with theoretical identification in other fields fail to supply it. They fail because if we construe the reference of mental terms to physical events on the usual model, we either get a reappearance of separate subjective events as the effects through which mental reference to physical events is secured, or else we get a false account of how mental terms refer (for example, a causal behaviorist one).

Strangely enough, we may have evidence for the truth of something we cannot really understand. Suppose a caterpillar is locked in a sterile safe by someone unfamiliar with insect metamorphosis, and weeks later the safe is reopened, revealing a butterfly. If the person knows that the safe has been shut the whole time, he has reason to believe that the butterfly is or was once the caterpillar, without having any idea in what sense this might be so. (One possibility is that the caterpillar contained a tiny winged parasite that devoured it and grew into the butterfly.)

It is conceivable that we are in such a position with regard to physicalism. Donald Davidson has argued that if mental events have physical causes and effects, they must have physical descriptions. He holds that we have reason to believe this even though we do not—and in fact could not—have a general psychophysical theory.[46] His argument applies to intentional mental events, but I think we also have some reason to believe that sensations are physical processes, without being in a position to understand how. Davidson’s position is that certain physical events have irreducibly mental properties, and perhaps some view describable in this way is correct. But nothing of which we can now form a conception corresponds to it; nor have we any idea what a theory would be like that enabled us to conceive of it.[47]

Very little work has been done on the basic question (from which mention of the brain can be entirely omitted) whether any sense can be made of experiences’ having an objective character at all. Does it make sense, in other words, to ask what my experiences are really like, as opposed to how they appear to me? We cannot genuinely understand the hypothesis that their nature is captured in a physical description unless we understand the more fundamental idea that they have an objective nature (or that objective processes can have a subjective nature).[48]

I should like to close with a speculative proposal. It may be possible to approach the gap between subjective and objective from another direction. Setting aside temporarily the relation between the mind and the brain, we can pursue a more objective understanding of the mental in its own right. At present we are completely unequipped to think about the subjective character of experience without relying on the imagination—without taking up the point of view of the experiential subject. This should be regarded as a challenge to form new concepts and devise a new method—an objective phenomenology not dependent on empathy or the imagination. Though presumably it would not capture everything, its goal would be to describe, at least in part, the subjective character of experiences in a form comprehensible to beings incapable of having those experiences.

We would have to develop such a phenomenology to describe the sonar experiences of bats; but it would also be possible to begin with humans. One might try, for example, to develop concepts that could be used to explain to a person blind from birth what it was like to see. One would reach a blank wall eventually, but it should be possible to devise a method of expressing in objective terms much more than we can at present, and with much greater precision. The loose intermodal analogies—for example, “Red is like the sound of a trumpet”—which crop up in discussions of this subject are of little use. That should be clear to anyone who has both heard a trumpet and seen red. But structural features of perception might be more accessible to objective description, even though something would be left out. And concepts alternative to those we learn in the first person may enable us to arrive at a kind of understanding even of our own experience which is denied us by the very ease of description and lack of distance that subjective concepts afford.

Apart from its own interest, a phenomenology that is in this sense objective may permit questions about the physical[49] basis of experience to assume a more intelligible form. Aspects of subjective experience that admitted this kind of objective description might be better candidates for objective explanations of a more familiar sort. But whether or not this guess is correct, it seems unlikely that any physical theory of mind can be contemplated until more thought has been given to the general problem of subjective and objective. Otherwise we cannot even pose the mind-body problem without sidestepping it.

Reflections

There is a famous puzzle in mathematics and physics courses. It asks, “Why does a mirror reverse left and right, but not up and down?” It gives many people pause for thought, and if you don’t want to be told the answer, skip the next two paragraphs.

The answer hinges on what we consider a suitable way to project ourselves onto our mirror images. Our first reaction is that by walking forward a few steps and then spinning around on our heels, we could step into the shoes of “that person” there in the mirror—forgetting that the heart, appendix, and so forth of “that person” are on the wrong side. The language hemisphere of the brain is, in all probability, on the nonstandard side. On a gross anatomical level, that image is actually of a nonperson. Microscopically, the situation is even worse. The DNA molecules coil the wrong way, and the mirror-“person” could no more mate with a real person than could a nosrep!

But wait—you can get your heart to stay on the proper side if, instead, you flip yourself head over heels, as if swinging over a waist-high horizontal bar in front of you. Now your heart is on the same side as the mirror-person’s heart—but your feet and head are in the wrong places, and your stomach, although at approximately the right height, is upside-down. So it seems a mirror can be perceived as reversing up and down, provided you’re willing to map yourself onto a creature whose feet are above its head. It all depends on the ways that you are willing to slip yourself onto another entity. You have a choice of twirling around a horizontal or a vertical bar, and getting the heart right but not the head and feet, or getting the head and feet right but not the heart. It’s simply that, because of the external vertical symmetry of the human body, the vertical self-twirling yields a more plausible-seeming you-to-image mapping. But mirrors intrinsically don’t care which way you interpret what they do. And in fact, all they really reverse is back and front!

There is something very beguiling about this concept of mapping, projection, identification, empathy—whatever you want to call it. It is a basic human trait, practically irresistible. Yet it can lead us down very strange conceptual pathways. The preceding puzzle shows the dangers of over facile self-projection. The refrain quoted from the country-western ballad reminds us more poignantly of the futility of taking such mapping too seriously. Yet we can’t stop our minds from doing it. So since we can’t, let’s go whole hog and indulge ourselves in an orgy of extravagant variations on the theme set by Nagel in his title.

What is it like to bat a bee? What is it like to be a bee being batted? What is it like to be a batted bee? (Illustration by Jim Hull.)

The image conjured up by the phrase “What is it like to be X”? is so seductive and tempting.... Our minds are so flexible, so willing to accept this notion, this idea that there is “something it is, like to be a bat.” Furthermore, we also willingly buy the idea that there are certain things that it is “like something to be”—“be-able things,” or “BATs” for short—such as bats, cows, people; and other things for which this doesn’t hold—such as balls, steaks, galaxies (even though a galaxy may contain innumerable be-able things). What is the criterion for “BAT-itude”?

In philosophical literature, many phrases have been used to try to evoke the right flavors for what being sentient really is (“being sentient” is one of them). Two old terms are “soul” and “anima.” These days, an “in” word is “intentionality.” There is the old standby, “consciousness.” Then there is “being a subject,” “having an inner life,” “having experience,” “having a point of view,” having “perceptual aboutness” or “personhood” or a “self” or “free will.” In some people’s eyes, “having a mind,” “being intelligent,” and just plain old “thinking” have the right flavors. In Searle’s article (selection 22), the contrast was drawn between “form” (hollow and mechanical) and “content” (alive and intentional); the words “syntactic” and “semantic” (or “meaningless” and “meaningful”) were also used to characterize this distinction. All of the terms in this huge showcase are nearly synonymous. They all have to do with the emotional issue of whether it makes sense to project ourselves onto the object in question: “Is this object a BAT, or not?” But is there really some thing to which they refer?

Nagel makes it clear that the “thing” he is after is a distillation of that which is common to the experiences of all bats; it is not the set of experiences of some particular bat. Thus, Searle might say Nagel is a “dualist,” since Nagel believes in some abstraction made from all those individuals’ experiences.

Surprisingly enough, a look at the grammar of sentences that invite the reader to perform a mental mapping yields some insights into these tricky matters. Consider, for instance, the contrast between the questions “What would it be like to be Indira Gandhi?” and “What is it like to be Indira Gandhi?” The conditional sentence forces you to project yourself into the “skin,” so to speak, of another human, whereas the indicative sentence seems to be asking what it is like for Indira Gandhi to be Indira Gandhi. The question might still be asked, “Described in whose terms?” Were Indira Gandhi to try to tell you what it is like to be Indira Gandhi, she might try to explain matters of political life in India by referring to things she considered vaguely analogous in your own experience. Would you protest and say, “No, don’t translate it into my terms! Say it in your own terms! Tell me what it is like—to Indira Gandhi—for Indira Gandhi to be Indira Gandhi!” In that case, of course, she might as well speak in Hindi and leave it to you to learn the language. And yet even then you would just be in the position of millions of native Hindi speakers who have no idea what it would be like to be Indira Gandhi—much less what it is like for Indira Gandhi to be Indira Gandhi....

Something seems very wrong here. Nagel is insistent that he wants his verb “be” to be subjectless, in effect. Not “What would it be like for me to be X”? but “What is it like, objectively, to be X?” There is a “be-ee” here, with no “be-er”—a living beast without a head, as it were. Perhaps we ought to go back to the conditional version: “What would it be like to be Indira Gandhi?” Well, for me, or for her? Poor Indira—where does she go while I’m being her? Or if we turn it around (identity being a symmetric relationship), we get “What would it be like for Indira Gandhi to be me?” Once again, where would I be if she were me? Would we have traded places? Or would we have temporarily collapsed two separate “souls” into one?

Note that we tend to say “If she were me” rather than “If she were I.” Many European languages are somewhat skittish about equations of this type. It sounds funny to use the nominative case in both the subject and complement positions. People prefer to use “be” with the accusative case, as if it were somehow a transitive verb! “Be” is not a transitive verb, but a symmetric one—yet language tilts us away from that symmetric vision.

We can see this in German, where one has interesting alternatives for constructing such identity-asserting sentences. Two examples follow, adapted from the German translation of a Stanislaw Lem dialogue in which an exact molecule-for-molecule replica of a doomed person is about to be constructed. In that spirit, we provide (nearly) exact word-for-word replicas in English of the German originals:

1. Ob die Kopie wirklich du bist, dafür muss der Beweis noch erbracht werden.

(As-to-whether the copy really you are, thereof must the proof still provided be.)

2. Die Kopie wird behaupten, daß sie du ist. (The copy will claim that it you is.)

Observe that in both identity-asserting clauses, “the copy” (or “it”) appears first, then “you,” then the verb. But notice—in the first clause, “are” is the verb, which retroactively implies that “you” was the subject and “the copy” was the complement, whereas in the second clause, the verb is “is,” retroactively implying that the subject was “it” and the complement was “you.” The fact that the verb comes at the end gives these clauses a sort of surprise-ending quality. In English we can’t achieve precisely the same effect comfortably, but we can ask for the difference in shades of meaning between the sentences “Is the copy really you?” and “Are you really the copy?” These two questions “slip” in our minds along different dimensions. The former slips into “Or is the copy really someone else—or perhaps no one at all?” The latter slips into “Or are you somewhere else—or are you anywhere?” Our book’s title, incidentally, can be construed not only as a possessive, but equally as a short full sentence reply to the two questions “Who am I?” and “Who is me?” Notice how the transitive usage—strictly speaking, an ungrammatical usage of “to be”—gives the second question a quite different “flavor” from the first.

[D.C.D. to D.R.H.: If I were you, I’d mention how curious it would be to preface some advice with “If you were me, I’d …” but if you were me, would I suggest that you mention it?]

All of these examples show how suggestible we are. We just fall like a ton of bricks for the notion that there’s a “soul” in there—a flamelike soul that can flicker on or off, or even be transferred between bodies as a flame between candles. If a candle blows out and is relit, is it “the same flame”? Or, if it stays lit, is it even “the same flame” from moment to moment? The Olympic Torch is carefully kept burning as it is carried by runners thousands of miles from Athens to its destination every four years. There is powerful symbolism to the idea that this is “the very flame that was lit in Athens.” Even the shortest break in the chain, however, would ruin the symbolism for people who knew. For people who didn’t know, of course, no harm done! How on earth could it possibly matter? Yet emotionally it seems to. It will not easily be extinguished, that “soulflame” notion. Yet it leads us into so much hot water.

We certainly intuit that only things of approximately the “same-sized souls” can slip into each other. The science-fiction story Flowers for Algernon by Daniel Keyes is about a retarded young man who by a miracle medical treatment slowly gains in intelligence and becomes a great genius—but then it turns out that the effects of the treatment cannot last, and “he” witnesses his own mental crumbling back into his retarded state. This fictional story has its counterpart in the real-life tragedy of people who, having grown from a state of zero mind to normal adult intelligence, witness themselves growing senile or who suffer serious brain damage. Can they answer for us the question “What is it like to have your soul slip out from under you?” any better than someone with vivid imagination can, though?

Franz Kafka’s Metamorphosis is the story of a young man who wakes up one morning transformed into a giant beetle. But the beetle thinks like a person. It would be interesting to combine the Flowers for Algernon idea with the Metamorphosis idea and imagine the experiences of an insect whose intelligence rises to the level of a human genius (why not superhuman, for that matter?), then sinks back to the insect level. Yet this is virtually impossible for us to conceive. To borrow electrical-engineering jargon, the “impedance match” of the minds involved is too poor. In fact, impedance match may well be the main criterion for the plausibility of questions of the form Nagel poses. Which is it easier for you to imagine being—the totally fictional character Holden Caulfield or some particular, actual bat? Of course it is much easier to map yourself onto a fictional human than onto a real bat—much easier, much realer. This is slightly surprising. It seems that Nagel’s verb “be” acts very strangely sometimes. Perhaps, as was suggested in the dialogue on the Turing test, the verb “be” is being extended. Perhaps it is even being stretched beyond its limits!

There’s something very fishy about this whole idea. How can something be something that it isn’t? And how is it rendered any more plausible when both things can “have experience”? It makes almost no sense for us to ask ourselves such questions as, “What would it be like for that black spider over there to be that mosquito trapped in its web?” Or worse yet, “What would it be like for my violin to be my guitar?” or “What would this sentence be like if it were a hippopotamus?” Like for whom? For the various objects concerned, sentient or not? For us the perceivers? Or, again, “objectively”?

This is the sticking-point of Nagel’s article. He wants to know if it is possible to give, in his own words, “a description [of the real nature of human experience] in terms accessible to beings that could not imagine what it was like to be us.” Put so starkly, it sounds like a blatant contradiction—and indeed, that is his point. He doesn’t want to know what it’s like for him to be a bat. He wants to know objectively what it is subjectively like. It wouldn’t be enough for him to have had the experience of donning a “batter’s helmet”—a helmet with electrodes that would stimulate his brain into batlike experiences—and to have thereby experienced “batitude.” This would, after all, merely be what it would be like for Nagel to be a bat. What, then, would satisfy him? He’s not sure that anything would, and that’s what worries him. He fears that this notion of “having experience” is beyond the realm of the objective.

Now perhaps the most objective-sounding of the various synonyms earlier listed for BAT-itude is “having a point of view.” After all, even the most dogmatic of disbelievers in machine intelligence would probably begrudgingly impute a “point of view” to a computer program that represents some facts about the world and about its own relationship to the world. There is no arguing with the fact that a computer can be programmed to describe the world around it in terms of a frame of reference centered on the machine itself, as in this: “Three minutes ago, the Teddy bear was thirty-five leagues due east of here.” Such a “here centered, now-centered” frame of reference constitutes a rudimentary “egocentric” point of view. “Being here now” is a central experience for any “I.” Yet how can you define “now” and “here” without making reference to some “I”? Is circularity inevitable?

Let us ponder for a moment on the connection of “I” and “now.” What would it be like to be a person who had grown up normally, thus with ordinary perceptual and linguistic capacities, but who then suffered some brain damage and was left without the capacity to convert the reverberating neural circuits of short-term memory into long-term memories? Such a person’s sense of existence would extend to only a few seconds on either side of “now.” There would be no large-scale sense of continuity of self—no internal vision of a chain of selves stretching both directions in time, making one coherent person.

When you get a concussion, the few instants before it happened are obliterated from your mind, as if you had never been conscious at that time. Just think—if you were knocked on the head at this moment, there would be no permanent trace left in your brain of your having read these past few sentences. Who, then, has been experiencing them? Does an experience only become part of you once it has been committed to long-term memory? Who is it that has dreamt all those many dreams you don’t remember one bit of?

Just as “now” and “I” are closely related terms, so are “here” and “I.” Consider the fact that you are now experiencing death, in a curious way. Not being in Paris right now, you know what it is like to be dead in Paris. No lights, no sounds—nothing. The same goes for Timbuctu. In fact, you are dead everywhere—except for one small spot. Just think how close you are to being dead everywhere! And you are also dead in all other moments than right now. That one small piece of space-time you are alive in doesn’t just happen to be where your body is now—it is defined by your body and by the concept of “now.” Our languages all have words that incorporate a rich set of associations with “here” and “now” namely, “I” and “me” and so on.

Now to program a computer to use words like “I” and “me” and “my” in describing its own relation to the world is a common thing. Of course, behind those words there need not stand any sophisticated self-concept—but there may. In essence, any physical representational system, as defined earlier in the commentary on the “Prelude, Ant Fugue” (selection 11), is an embodiment of some point of view, however modest. This explicit connection between “having a point of view” and “being a representational system” now provides a step forward in thinking about BAT-itude, for if we can equate BATs with physical representational systems of sufficient richness in their repertoire of categories and sufficiently well-indexed memories of their worldlines, we will have objectified at least some of subjectivity.

It should be pointed out that what is strange about the idea of “being a bat” is not that bats sense the outside world in a bizarre way—it is that bats clearly have a highly reduced collection of conceptual and perceptual categories, compared to what we humans have. Sensory modalities are surprisingly interchangeable and equivalent, in some sense. For instance, it is possible to induce visual experiences in both blind and sighted people through the sensation of touch. A grid of over a thousand stimulators driven by a television camera is placed against a person’s back. The sensations are carried to the brain where their processing can induce the having of visual experiences. A sighted woman reports on her experience of prosthetic vision:

Similar transcending of modality in sensory input is well known. As has been pointed out in earlier selections, people who wear prism-shaped glasses that turn everything upside down can, after two or three weeks, get quite used to seeing the world this way. And, on a more abstract plane, people who learn a new language still experience the world of ideas in pretty much the same way.

So it is really not the mode of transduction of stimuli into percepts or the nature of the thought-supporting medium that makes the “bat Weltanschauung” different from ours. It is the severely limited set of categories, together with the stress on what is important in life and what is not. It is the fact that bats cannot form notions such as “the human Weltanschauung” and joke about them, because they are too busy, always being in raw-survival mode.

What Nagel’s question forces us to think about—and think very hard about—is how we can map our mind onto that of a bat. What kind of representational system is the mind of a bat? Can we empathize with a bat? In this view, Nagel’s question seems intimately connected to the way in which one representational system emulates another, as discussed in the Reflections on selection 22. Would we learn something by asking a Sigma-5, “What is it like to be a DEC?” No, that would be a silly question. The reason it would be silly is this. An unprogrammed computer is not a representational system. Even when one computer has a program allowing it to emulate another, this does not give it the representational power to deal with the concepts involved in such a question. For that it would need a very sophisticated AI program—one that, among other things, could use the verb “be” in all the ways we do (including Nagel’s extended sense). The question to ask would be, rather, “What is it like for you, as a self-understanding AI program, to emulate another such program?” But then this question starts to resemble very strongly the question “What is it like for one person to empathize strongly with another?”

As we pointed out earlier, people do not have the patience or accuracy to emulate a computer for any length of time. When trying to put themselves in the shoes of other BATs, people tend to empathize, not to emulate. They “subvert” their own internal symbol systems by voluntarily adopting a global set of biases that modify the cascades of symbolic activity in their brains. It is not quite the same as taking LSD, although that too creates radical changes in the way that neurons communicate with one another. LSD does so unpredictably. Its effects depend on how it is spread about inside the brain, and that has nothing to do with what symbolizes what. LSD affects thought in somewhat the same way that having a bullet shot through your brain would affect thought—neither intrusive substance pays any regard to the symbolic power of the stuff in the brain.

But a bias established through symbolic channels—“Hey, let me think about how it would feel to be a bat”—sets up a mental context. Translated into less mentalistic and more physical terms, the act of trying to project yourself into a bat’s point of view activates some symbols in your brain. These symbols, as long as they remain activated, will contribute to the triggering patterns of all the other symbols that are activated. And the brain is sufficiently sophisticated that it can treat certain activations as stable—that is, as contexts—and other symbols then are activated in a subordinate manner. So when we attempt to “think bat,” we subvert our brains by setting up neural contexts that channel our thoughts along different pathways than they usually follow. (Too bad we can’t just “think Einstein” when we want!)

All this richness, however, cannot get us all the way to batitude. Each person’s self-symbol—the “personal nucleus,” or “gemma” in Lem’s personetics—has become, over his or her life, so large and complicated and idiosyncratic that it can no longer, chameleonlike, just assume the identity of another person or being. Its individual history is just too wound up in that little “knot” of a self-symbol.

It is interesting to think about two systems that are so alike that they have isomorphic, or identical, self-symbols—say a woman and an atom-by-atom replica of her. If she thinks about herself, is she also thinking about her replica? Many people fantasize that somewhere out there in the heavens, there is another person just like them. When you think about yourself, are you also thinking, without being aware of it, about that person? Who is that person thinking about right now? What would it be like to be that person? Are you that person? If you had a choice, would you let that person be killed, or yourself?

The one thing that Nagel seems not to have acknowledged in his article is that language (among other things) is a bridge that allows us to cross over into territory that is not ours. Bats don’t have any idea of “what it is like to be another bat” and don’t wonder about it, either. And that is because bats do not have a universal currency for the exchange of ideas, which is what language, movies, music, gestures, and so on give us. These media aid in our projection, aid us in absorbing foreign points of view. Through a universal currency, points of view become more modular, more transferable, less personal and idiosyncratic.

Knowledge is a curious blend of objective and subjective. Verbalizable knowledge can be passed around and shared, to the extent that words really “mean the same thing” to different people. Do two people ever speak the same language? What we mean by “speak the same language” is a prickly issue. We accept and take for granted that the hidden subterranean flavors are not shared. We know what comes with and what is left out of linguistic transactions, more or less. Language is a public medium for the exchange of the most private experiences. Each word is surrounded, in each mind, by a rich and inimitable cluster of concepts, and we know that no matter how much we try to bring to the surface, we always miss something. All we can do is approximate. (See George Steiner’s After Babel for an extended discussion of this idea.)

By means of meme-exchange media (see selection 10, “Selfish Genes and Selfish Memes”) such as language and gestures, we can experience (vicariously sometimes) what it is like to be or do X. It’s never genuine, but then what is genuine knowledge of what it is like to be X? We don’t even quite know what it was like to be ourselves ten years ago. Only by rereading diaries can we tell—and then, only by projection! It is still vicarious. Worse yet, we often don’t even know how we could possibly have done what we did yesterday. And, when you come right down to it, it’s not so clear just what it is like to be me, right now.

Language is what gets us into this problem (by allowing us to see the question) and what helps to get us out as well (by being a universal thought-exchange medium, allowing experiences to become sharable and more objective). However, it can’t pull us all the way.

In a sense, Gödel’s Theorem is a mathematical analogue of the fact that I cannot understand what it is like not to like chocolate, or to be a bat, except by an infinite sequence of ever-more-accurate simulation processes that converge toward, but never reach, emulation. I am trapped inside myself and therefore can’t see how other systems are. Gödel’s Theorem follows from a consequence of that general fact: I am trapped inside myself and therefore can’t see how other systems see me. Thus the objectivity-subjectivity dilemmas that Nagel has sharply posed are somehow related to epistemological problems in both mathematical logic, and as we saw earlier, the foundations of physics. These ideas are developed in more detail in the last chapter of Gödel, Escher, Bach by Hofstadter.

D.R.H.

25 Raymond M. Smullyan An Epistemological Nightmare[50]

Scene 1. Frank is in the office of an eye doctor. The doctor holds up a book and asks “What color is it?” Frank answers, “Red.” The doctor says, “Aha, just as I thought! Your whole color mechanism has gone out of kilter. But fortunately your condition is curable, and I will have you in perfect shape in a couple of weeks.”

Scene 2. (A few weeks later.) Frank is in a laboratory in the home of an experimental epistemologist. (You will soon find out what that means!) The epistemologist holds up a book and also asks, “What color is this book?” Now, Frank has been earlier dismissed by the eye doctor as “cured.” However, he is now of a very analytical and cautious temperament, and will not make any statement that can possibly be refuted. So Frank answers, “It seems red to me.”

EPISTEMOLOGIST: Wrong!

FRANK: I don’t think you heard what I said. I merely said that it seems red to me.

EPISTEMOLOGIST: I heard you, and you were wrong.

FRANK: Let me get this clear; did you mean that I was wrong that this book is red, or that I was wrong that it seems red to me?

EPISTEMOLOGIST: I obviously couldn’t have meant that you were wrong in that it is red, since you did not say that it is red. All you said was that it seems red to you, and it is this statement which is wrong.

FRANK: But you can’t say that the statement “It seems red to me” is wrong.

EPISTEMOLOGIST: If I can’t say it, how come I did?

FRANK: I mean you can’t mean it.

EPISTEMOLOGIST: Why not?

FRANK: But surely I know what color the book seems to me!

EPISTEMOLOGIST: Again you are wrong.

FRANK: But nobody knows better than I how things seem to me.

EPISTEMOLOGIST: I am sorry, but again you are wrong.

FRANK: But who knows better than I?

EPISTEMOLOGIST: I do.

FRANK: But how could you have access to my private mental states?

EPISTEMOLOGIST: Private mental states! Metaphysical hogwash! Look, I am a practical epistemologist. Metaphysical problems about “mind” versus “matter” arise only from epistemological confusions. Epistemology is the true foundation of philosophy. But the trouble with all past epistemologists is that they have been using wholly theoretical methods, and much of their discussion degenerates into mere word games. While other epistemologists have been solemnly arguing such questions as whether a man can be wrong when he asserts that he believes such and such, I have discovered how to settle such questions experimentally.

FRANK: How could you possibly decide such things empirically?

EPISTEMOLOGIST: By reading a person’s thoughts directly.

FRANK: You mean you are telepathic?

EPISTEMOLOGIST: Of course not. I simply did the one obvious thing which should be done, viz. I have constructed a brain-reading machine—known technically as a cerebrescope—that is operative right now in this room and is scanning every nerve cell in your brain. I thus can read your every sensation and thought, and it is a simple objective truth that this book does not seem red to you.

FRANK (thoroughly subdued): Goodness gracious, I really could have sworn that the book seemed red to me; it sure seems that it seems red to me!

EPISTEMOLOGIST: I’m sorry, but you are wrong again.

FRANK: Really? It doesn’t even seem that it seems red to me? It sure seems like it seems like it seems red to me!

EPISTEMOLOGIST: Wrong again! And no matter how many times you reiterate the phrase “it seems like” and follow it by “the book is red” you will be wrong.

FRANK: This is fantastic! Suppose instead of the phrase “it seems like” I would say “I believe that.” So let us start again at ground level. I retract the statement “It seems red to me” and instead I assert “I believe that this book is red.” Is this statement true or false?

EPISTEMOLOGIST: Just a moment while I scan the dials of the brainreading machine—no, the statement is false.

FRANK: And what about “I believe that I believe that the book is red”?

EPISTEMOLOGIST (consulting his dials): Also false. And again, no matter how many times you iterate “I believe,” all these belief sentences are false.

FRANK: Well, this has been a most enlightening experience. However, you must admit that it is a little hard on me to realize that I am entertaining infinitely many erroneous beliefs!

EPISTEMOLOGIST: Why do you say that your beliefs are erroneous?

FRANK: But you have been telling me this all the while!

EPISTEMOLOGIST: I most certainly have not!

FRANK: Good God, I was prepared to admit all my errors, and now you tell me that my beliefs are not errors; what are you trying to do, drive me crazy?

EPISTEMOLOGIST: Hey, take it easy! Please try to recall: When did I say or imply that any of your beliefs are erroneous?

FRANK: Just simply recall the infinite sequence of sentences: (1) I believe this book is red; (2) I believe that I believe this book is red; and so forth. You told me that every one of those statements is false.

EPISTEMOLOGIST: True.

FRANK: Then how can you consistently maintain that my beliefs in all these false statements are not erroneous?

EPISTEMOLOGIST: Because, as I told you, you don’t believe any of them.

FRANK: I think I see, yet I am not absolutely sure.

EPISTEMOIOGIST: Look, let me put it another way. Don’t you see that the very falsity of each of the statements that you assert saves you from an erroneous belief in the preceding one? The first statement is, as I told you, false. Very well! Now the second statement is simply to the effect that you believe the first statement. If the second statement were true, then you would believe the first statement, and hence your belief about the first statement would indeed be in error. But fortunately the second statement is false, hence you don’t really believe the first statement, so your belief in the first statement is not in error. Thus the falsity of the second statement implies you do not have an erroneous belief about the first; the falsity of the third likewise saves you from an erroneous belief about the second, etc.

FRANK: Now I see perfectly! So none of my beliefs were erroneous, only the statements were erroneous.

EPISTEMOLOGIST: Exactly.

FRANK: Most remarkable! Incidentally, what color is the book really?

EPISTEMOLOGIST: It is red.

FRANK: What!

EPISTEMOLOGIST: Exactly! Of course the book is red. What’s the matter with you, don’t you have eyes?

FRANK: But didn’t I in effect keep saying that the book is red all along?

EPISTEMOLOGIST: Of course not! You kept saying it seems red to you, it seems like it seems red to you, you believe it is red, you believe that you believe it is red, and so forth. Not once did you say that it is red. When I originally asked you “What color is the book?” if you had simply answered “red,” this whole painful discussion would have been avoided.

Scene 3. Frank comes back several months later to the home of the epistemologist.

EPISTEMOLOGIST: How delightful to see you! Please sit down.

FRANK (seated): I have been thinking of our last discussion, and there is much I wish to clear up. To begin with, I discovered an inconsistency in some of the things you said.

EPISTEMOLOGIST: Delightful! I love inconsistencies. Pray tell!

FRANK: Well, you claimed that although my belief sentences were false, I did not have any actual beliefs that are false. If you had not admitted that the book actually is red, you would have been consistent. But your very admission that the book is red, leads to an inconsistency.

EPISTEMOLOGIST: How so?

FRANK: Look, as you correctly pointed out, in each of my belief sentences “I believe it is red,” “I believe that I believe it is red,” the falsity of each one other than the first saves me from an erroneous belief in the preceeding one. However, you neglected to take into consideration the first sentence itself. The falsity of the first sentence “I believe it is red,” in conjunction with the fact that it is red, does imply that I do have a false belief.

EPISTEMOLOGIST: I don’t see why.

FRANK: It is obvious! Since the sentence “I believe it is red” is false, then I in fact believe it is not red, and since it really is red, then I do have a false belief. So there!

EPISTEMOLOGIST (disappointed): I am sorry, but your proof obviously fails. Of course the falsity of the fact that you believe it is red implies that you don’t believe it is red. But this does not mean that you believe it is not red!!

FRANK: But obviously I know that it either is red or it isn’t, so if I don’t believe it is, then I must believe that it isn’t.

EPISTEMOLOGIST: Not at all. I believe that either Jupiter has life or it doesn’t. But I neither believe that it does, nor do I believe that it doesn’t. I have no evidence one way or the other.

FRANK: Oh well, I guess you are right. But let us come to more important matters. I honestly find it impossible that I can be in error concerning my own beliefs.

EPISTEMOLOGIST: Must we go through this again? I have already patiently explained to you that you (in the sense of your beliefs, not your statements) are not in error.

FRANK: Oh, all right then, I simply do not believe that even the statements are in error. Yes, according to the machine they are in error, but why should I trust the machine?

EPISTEMOLOGIST: Whoever said you should trust the machine?

FRANK: Well, should I trust the machine?

EPISTEMOLOGIST: That question involving the word “should” is out of my domain. However, if you like, I can refer you to a colleague who is an excellent moralist—he may be able to answer this for you.

FRANK: Oh come on now, I obviously didn’t mean “should” in a moralistic sense. I simply meant “Do I have any evidence that this machine is reliable?”

EPISTEMOLOGIST: Well, do you?

FRANK: Don’t ask me! What I mean is should you trust the machine?

EPISTEMOLOGIST: Should I trust it? I have no idea, and I couldn’t care less what I should do.

FRANK: Oh, your moralistic hangup again. I mean, do you have evidence that the machine is reliable?

EPISTEMOLOGIST: Well of course!

FRANK: Then let’s get down to brass tacks. What is your evidence?

EPISTEMOLOGIST: You hardly can expect that I can answer this for you in an hour, a day, or a week. If you wish to study this machine with me, we can do so, but I assure you this is a matter of several years. At the end of that time, however, you would certainly not have the slightest doubts about the reliability of the machine.

FRANK: Well, possibly I could believe that it is reliable in the sense that its measurements are accurate, but then I would doubt that what it actually measures is very significant. It seems that all it measures is one’s physiological states and activities.

EPISTEMOLOGIST: But of course, what else would you expect it to measure?

FRANK: I doubt that it measures my psychological states, my actual beliefs.

EPISTEMOLOGIST: Are we back to that again? The machine does measure those physiological states and processes that you call psychological states, beliefs, sensations, and so forth.

FRANK: At this point I am becoming convinced that our entire difference is purely semantical. All right, I will grant that your machine does correctly measure beliefs in your sense of the word “belief,” but I don’t believe that it has any possibility of measuring beliefs in my sense of the word “believe.” In other words I claim that our entire deadlock is simply due to the fact that you and I mean different things by the word “belief.”

EPISTEMOLOGIST: Fortunately, the correctness of your claim can he decided experimentally. It so happens that I now have two brain-reading machines in my office, so I now direct one to your brain to find out what you mean by “believe” and now I direct the other to my own brain to find out what I mean by “believe,” and now I shall compare the two readings. Nope, I’m sorry, but it turns out that we mean exactly the same thing by the word “believe.”

FRANK: Oh, hang your machine! Do you believe we mean the same thing by the word “believe”?

EPISTEMOLOGIST: Do I believe it? just a moment while I check with the machine. Yes, it turns out I do believe it.

FRANK: My goodness, do you mean to say that you can’t even tell me what you believe without consulting the machine?

EPISTEMOLOGIST: Of course not. But most people when asked what they believe simply tell you. Why do you, in order to find out your beliefs, go through the fantastically roundabout process of directing a thought-reading machine to your own brain and then finding out what you believe on the basis of the machine readings?

EPISTEMOLOGIST: What other scientific, objective way is there of finding out what I believe?

FRANK: Oh, come now, why don’t you just ask yourself?

EPISTEMOLOGIST (sadly): It doesn’t work. Whenever I ask myself what I believe, I never get any answer!

FRANK: Well, why don’t you just state what you believe?

EPISTEMOLOGIST: How can I state what I believe before I know what I believe?

FRANK: Oh, to hell with your knowledge of what you believe; surely you have some idea or belief as to what you believe, don’t you?

EPISTEMOLOGIST: Of course I have such a belief. But how do I find out what this belief is?

FRANK: I am afraid we are getting into another infinite regress. Look, at this point I am honestly beginning to wonder whether you may be going crazy.

EPISTEMOLOGIST: Let me consult the machine. Yes, it turns out that I may be going crazy.

FRANK: Good God, man, doesn’t this frighten you?

EPISTEMOLOCIST: Let me check! Yes, it turns out that it does frighten me.

FRANK: Oh please, can’t you forget this damned machine and just tell me whether you are frightened or not?

EPISTEMOLOGIST: I just told you that I am. However, I only learned of this from the machine.

FRANK: I can see that it is utterly hopeless to wean you away from the machine. Very well, then, let us play along with the machine some more. Why don’t you ask the machine whether your sanity can be saved?

EPISTEMOLOGIST: Good idea! Yes, it turns out that it can be saved.

FRANK: And how can it be saved?

EPISTEMOLOGIST: I don’t know, I haven’t asked the machine.

FRANK: Well, for God’s sake, ask it!

EPISTEMOLOGIST: Good idea. It turns out that…

FRANK: It turns out what?

EPISTEMOLOGIST: It turns out that…

FRANK: Come on now, it turns out what?

EPISTEMOLOGIST: This is the most fantastic thing I have ever come across! According to the machine the best thing I can do is to cease to trust the machine!

FRANK: Good! What will you do about it?

EPISTEMOLOGIST: How do I know what I will do about it, I can’t read the future?

FRANK: I mean, what do you presently intend to do about it?

EPISTEMOLOGIST: Good question, let me consult the machine. According to the machine, my current intentions are in complete conflict. And I can see why! I am caught in a terrible paradox! If the machine is trustworthy, then I had better accept its suggestion to distrust it. But if I distrust it, then I also distrust its suggestion to distrust it, so I am really in a total quandary.

FRANK: Look, I know of someone who I think might be really of help in this problem. I’ll leave you for a while to consult him. Au revoir!

Scene 4. (Later in the day at a psychiatrist’s office.)

FRANK: Doctor, I am terribly worried about a friend of mine. He calls himself an “experimental epistemologist.”

DOCTOR: Oh, the experimental epistemologist. There is only one in the world. I know him well!

FRANK: That is a relief. But do you realize that he has constructed a mind-reading device that he now directs to his own brain, and whenever one asks him what he thinks, believes, feels, is afraid of, and so on, he has to consult the machine first before answering? Don’t you think this is pretty serious?

DOCTOR: Not as serious as it might seem. My prognosis for him is actually quite good.

FRANK: Well, if you are a friend of his, couldn’t you sort of keep an eye on him?

DOCTOR: I do see him quite frequently, and I do observe him much. However, I don’t think he can be helped by so-called “psychiatric treatment.” His problem is an unusual one, the sort that has to work itself out. And I believe it will.

FRANK: Well, I hope your optimism is justified. At any rate I sure think I need some help at this point!

DOCTOR: How so?

FRANK: My experiences with the epistemologist have been thoroughly unnerving! At this point I wonder if I may be going crazy; I can’t even have confidence in how things appear to me. I think maybe you could be helpful here.

DOCTOR: I would be happy to but cannot for a while. For the next three months I am unbelievably overloaded with work. After that, unfortunately, I must go on a three-month vacation. So in six months come back and we can talk this over.

Scene 5. (Same office, six months later.)

DOCTOR: Before we go into your problems, you will be happy to hear that your friend the epistemologist is now completely recovered.

FRANK: Marvelous, how did it happen?

DOCTOR: Almost, as it were, by a stroke of fate—and yet his very mental activities were, so to speak, part of the “fate.” What happened was this: For months after you last saw him, he went around worrying “should I trust the machine, shouldn’t I trust the machine, should I, shouldn’t I, should I, shouldn’t I.” (He decided to use the word “should” in your empirical sense.) He got nowhere! So he then decided to “formalize” the whole argument. He reviewed his study of symbolic logic, took the axioms of first-order logic, and added as nonlogical axioms certain relevant facts about the machine. Of course the resulting system was inconsistent—he formally proved that he should trust the machine if and only if he shouldn’t, and hence that he both should and should not trust the machine. Now, as you may know, in a system based on classical logic (which is the logic he used), if one can prove so much as a single contradictory proposition, then one can prove any proposition, hence the whole system breaks down. So he decided to use a logic weaker than classical logic—a logic close to what is known as “minimal logic”—in which the proof of one contradiction does not necessarily entail the proof of every proposition. However, this system turned out too weak to decide the question of whether or not he should trust the machine. Then he had the following bright idea. Why not use classical logic in his system even though the resulting system is inconsistent? Is an inconsistent system necessarily useless? Not at all! Even though given any proposition, there exists a proof that it is true and another proof that it is false, it may be the case that for any such pair of proofs, one of them is simply more psychologically convincing than the other, so simply pick the proof you actually believe! Theoretically the idea turned out very well—the actual system he obtained really did have the property that given any such pair of proofs, one of them was always psychologically far more convincing than the other. Better yet, given any pair of contradictory propositions, all proofs of one were more convincing than any proof of the other. Indeed, anyone except the epistemologist could have used the system to decide whether the machine could be trusted. But with the epistemologist, what happened was this: He obtained one proof that he should trust the machine and another proof that he should not. Which proof was more convincing to him, which proof did he really “believe”? The only way he could find out was to consult the machine! But he realized that this would be begging the question, since his consulting the machine would be a tacit admission that he did in fact trust the machine. So he still remained in a quandary.

FRANK: So how did he get out of it?

DOCTOR: Well, here is where fate kindly interceded. Due to his absolute absorption in the theory of this problem, which consumed about his every waking hour, he became for the first time in his life experimentally negligent. As a result, quite unknown to him, a few minor units of his machine blew out! Then, for the first time, the machine started giving contradictory information—not merely subtle paradoxes, but blatant contradictions. In particular, the machine one day claimed that the epistemologist believed a certain proposition and a few days later claimed he did not believe that proposition. And to add insult to injury, the machine claimed that he had not changed his belief in the last few days. This was enough to simply make him totally distrust the machine. Now he is fit as a fiddle.

FRANK: This is certainly the most amazing thing I have ever heard! I guess the machine was really dangerous and unreliable all along.

DOCTOR: Oh, not at all: the machine used to be excellent before the epistemologist’s experimental carelessness put it out of whack.

FRANK: Well, surely when I knew it, it couldn’t have been very reliable.

DOCTOR: Not so, Frank, and this brings us to your problem. I know about your entire conversation with the epistemologist—it was all tape-recorded.

FRANK: Then surely you realize the machine could not have been right when it denied that I believed the book was red.

DOCTOR: Why not?

FRANK: Good God, do I have to go through all this nightmare again? I can understand that a person can be wrong if he claims that a certain physical object has a certain property, but have you ever known a single case when a person can be mistaken when he claims to have or not have a certain sensation?

DOCTOR: Why, certainly! I once knew a Christian Scientist who had a raging toothache; he was frantically groaning and moaning all over the place. When asked whether a dentist might not cure him, he replied that there was nothing to be cured. Then he was asked, “But do you not feel pain?” He replied, “No, I do not feel pain; nobody feels pain, there is no such thing as pain, pain is only an illusion.” So here is a case of a man who claimed not to feel pain, yet everyone present knew perfectly well that he did feel pain. I certainly don’t believe he was lying, he was just simply mistaken.

FRANK: Well, all right, in a case like that. But how can one be mistaken if one asserts his belief about the color of a book?

DOCTOR: I can assure you that without access to any machine, if I asked someone what color is this book, and he answered. “I believe it is red,” I would be very doubtful that he really believed it. It seems me that if he really believed it, he would answer, “It is red” and not “I believe it is red” or “It seems red to me.” The very timidity of h response would be indicative of his doubts.

FRANK: But why on earth should I have doubted that it was red?

DOCTOR: You should know that better than I. Let us see now, have yon ever in the past had reason to doubt the accuracy of your sense perception?

FRANK: Why, yes. A few weeks before visiting the epistemologist, I suffered from an eye disease, which did make me see colors falsely. Bu I was cured before my visit.

DOCTOR: Oh, so no wonder you doubted it was red! True enough, your eyes perceived the correct color of the book, but your earlier experience lingered in your mind and made it impossible for you to really believe it was red. So the machine was right!

FRANK: Well, all right, but then why did I doubt that I believed it was true?

DOCTOR: Because you didn’t believe it was true, and unconsciously you were smart enough to realize the fact. Besides, when one starts doubting one’s own sense perceptions, the doubt spreads like an infection to higher and higher levels of abstraction until finally the whole belief system becomes one doubting mass of insecurity. I bet that if you went to the epistemologist’s office now, and if the machine were repaired, and you now claimed that you believe the book is red, the machine would concur.

No, Frank, the machine is—or, rather, was—a good one. The epistemologist learned much from it, but misused it when he applied it to his own brain. He really should have known better than to create such an unstable situation. The combination of his brain and the machine each scrutinizing and influencing the behavior of the other led to serious problems in feedback. Finally the whole system went into a cybernetic wobble. Something was bound to give sooner or later. Fortunately, it was the machine.

FRANK: I see. One last question, though. How could the machine be trustworthy when it claimed to be untrustworthy?

DOCTOR: The machine never claimed to be untrustworthy, it only claimed that the epistemologist would be better off not trusting it. And the machine was right.

Reflections

If Smullyan’s nightmare strikes you as too outlandish to be convincing, consider a more realistic fable—not a true story, but surely possible:

Once upon a time there were two coffee tasters, Mr. Chase and Mr. Sanborn, who worked for Maxwell House. Along with half a dozen other coffee tasters, their job was to ensure that the taste of Maxwell House stayed constant, year after year. One day, about six years after Mr. Chase had come to work for Maxwell House, he cleared his throat and confessed to Mr. Sanborn:

“You know, I hate to admit it, but I’m not enjoying this work any more. When I came to Maxwell House six years ago, I thought Maxwell House coffee was the best-tasting coffee in the world. I was proud to have a share in the responsibility for preserving that flavor over the years. And we’ve done our job well; the coffee tastes today just the way it tasted when I arrived. But, you know, I no longer like it! My tastes have changed. I’ve become a more sophisticated coffee drinker. I no longer like that taste at all.”

Sanborn greeted this revelation with considerable interest. “It’s funny you should mention it,” he replied, “for something rather similar has happened to me. When I arrived here, shortly before you did, I, like you, thought Maxwell House coffee was tops in flavor. And now I, like you, really don’t care for the coffee we’re making. But my tastes haven’t changed; my … tasters have changed. That is, I think something has gone wrong with my taste buds or something—you know, the way your taste buds go off when you take a bite of pancakes and maple syrup and then go back to your orange juice? Maxwell House coffee doesn’t taste to me the way it used to taste; if only it did, I’d still love it, for I still think that taste is the best taste in coffee. Now, I’m not saying we haven’t done our job well. You other guys all agree that the taste is the same, so it must be my problem alone. I guess I’m no longer cut out for this work.”

Chase and Sanborn are alike in one way. Both used to like Maxwell House coffee; now neither one likes it. But they claim to be different in another way: Maxwell House tastes to Chase the way it always did, but not so for Sanborn. The difference seems familiar and striking, yet when they confront each other, they may begin to wonder if the cases are really all that different. “Could it be,” Chase might wonder, “that Mr. Sanborn is really in my predicament and just hasn’t noticed the gradual rise in his standards and sophistication as a coffee taster?” “Could it be,” Sanborn might wonder, “that Mr. Chase is kidding himself when he says the coffee tastes just the same to him as it used to?”

Do you remember your first sip of beer? Terrible! How could anyone like that stuff? But beer, you reflect, is an acquired taste; one gradually trains oneself—or just comes—to enjoy that flavor. What flavor? The flavor of that first sip? No one could like that flavor! Beer tastes different to the experienced beer drinker. Then beer isn’t an acquired taste; one doesn’t learn to like that first taste; one gradually comes to experience a different, and likable, taste. Had the first sip tasted that way, you would have liked beer wholeheartedly from the beginning!

Perhaps, then, there is no separating the taste from the response to the taste, the judgment of good or bad. Then Chase and Sanborn might be just alike, and simply be choosing slightly different ways of expressing themselves. But if they were just alike, then they’d actually both be wrong about something, for they each have sincerely denied that they are like the other. Is it conceivable that each could have inadvertently misdescribed his own case and described the other’s instead? Perhaps Chase is the one whose taste buds have changed, while Sanborn is the sophisticate. Could they be that wrong?

Some philosophers—and other people—have thought that a person simply cannot be wrong about such a matter. Everyone is the final and unimpeachable arbiter of how it is with him; if Chase and Sanborn have spoken sincerely, and have made no unnoticed slips of language, and if both know the meanings of their words, they must have expressed the truth in each case. Can’t we imagine tests that would tend to confirm their different tales? If Sanborn does poorly on discrimination tests he used to pass with flying colors, and if, moreover, we find abnormalities in his taste buds (it’s all that Szechuan food he’s been eating lately, we discover), this will tend to confirm his view of his situation. And if Chase passes all those tests better than he used to, and exhibits increased knowledge of coffee types and a great interest in their relative merits and peculiar characteristics, this will support his view of himself. But if such tests could support Chase’s and Sanborn’s authority, failing them would have to undermine their authority. If Chase passed Sanborn’s tests and Sanborn passed Chase’s, each would have doubt cast on his account—if such tests have any bearing at all on the issue.

Another way of putting the point is that the price you pay for the possibility of confirming your authority is the outside chance of being discredited. “I know what I like,” we are all prepared to insist, “and I know what it’s like to be me!” Probably you do, at least about some matters, but that is something to be checked in performance. Maybe, just maybe, you’ll discover that you really don’t know as much as you thought you did about what it is like to be you.

D.C.D.

26 Douglas R. Hofstadter A Conversation with Einstein’s Brain

The Tortoise and Achilles bump into each other accidentally at the edge of one of the large octagonal ponds in the Jardin du Luxembourg in Paris, where young lads and lasses often take their small sailboats—and, in this day and age, even motorized and radio-controlled boats. But this is beside the point. It is a pleasant fall day.

ACHILLES: Why, Mr. Tortoise! I thought you were back in the fifth century B.C.!

TORTOISE: What about yourself? As for me, I often stroll through the centuries. It’s good for the spleen, and besides, I find it refreshing on a pleasant fall day to meander among the bushes and trees, watching children grow old and die, only to be supplanted by a new generation of equally brainless, but generally rambunctious, human beings. Ah, what a harried existence it must be, to be a member of that feeble-minded species. Oh—pardon me! Indeed, I totally forgot I was addressing a member of that noble race. Why, you, Achilles, of course are an exception to the rule (thereby proving it, as the common human “logic” has it). You have been known, on occasion, to come out with truly insightful comments about the human condition (even if they were, to some extent, more or less accidental and unintended!). I feel very privileged to have known you, of all the human race, Achilles.

ACHILLES: Why, how kind of you to say those things about me. I’m sure I hardly deserve them. But, getting back to our chance meeting, I happen to be here today to have some footraces with a friend. However, he did not show up, so I am led to guess that he had sized up his chances and decided to spend his day some more profitable way. So here I am with nothing particular to occupy me, a leisurely day ahead of me to stroll about, watching the people (and Tortoises), and musing on philosophical matters, which, as you know, is a hobby of mine.

TORTOISE: Ah, yes. As a matter of fact, I too have been musing somewhat over some somewhat amusing ideas. Perhaps you’d like me to share them with you?

ACHILLES: Oh, I should be delighted. That is, I should be delighted as long as you’re not going to try to snare me in one of your wicked traps of logic, Mr. T.

TORTOISE: Wicked traps? Oh, you do me wrong. Would I do anything wicked? I’m a peaceful soul, bothering nobody and leading a gentle, herbivorous life. And my thoughts merely drift among the oddities and quirks of how things are (as I see them). I, humble observer of phenomena, plod along and puff my silly words into the air rather unspectacularly, I am afraid. But to reassure you about my intentions, I was only planning to speak of brains and minds this fine day—and as you know, of course those things have nothing—nothing whatsoever—to do with logic!

ACHILLES: Your words do reassure me, Mr. T. And, in fact, my curiosity is quite piqued; I would certainly like to listen to what you have to say, even if it is unspectacular.

TORTOISE: You’re a tolerant soul, Achilles—a praiseworthy way to be. Well, we’re about to broach a difficult subject, so I will ease us gently into the waters by means of an analogy. You are familiar with “playing-records,” aren’t you—the kind of grooved plastic platters upon which are imprinted fine, near-microscopic patterns?

ACHILLES: Indeed I am. Music is stored upon them.

TORTOISE: Music? I thought music was something to listen to.

ACHILLES: Yes, it is, to be sure. But one can listen to playing-records.

TORTOISE: I suppose. If you put them up next to your ear. But they must make awfully silent music.

ACHILLES: Oh, surely, Mr. T, you are joking. Haven’t you ever listened to the music stored upon a playing-record?

TORTOISE: To tell the truth, I have been inspired, at times, upon glancing at some playing-records, to hum tunes. Is that it?

ACHILLES: Hardly. You see, you put them on a rotating turntable a place a thin needle, which is affixed within a long arm, in the outermost groove, and—well, the details are too much for me, but the end result is that you hear the glorious sounds of music coming out a device called a loudspeaker.

TORTOISE: I see, yet I don’t see; why don’t you just use the loudspeaker and dispense with the other paraphernalia?

ACHILLES: No—you see, the music is not stored in the loudspeaker; it is in the record.

TORTOISE: In the record? But the record is there all at once; music, as I know it, comes slowly, a bit at a time. Isn’t that so?

ACHILLES: You are right on both counts. But even though the record is there “all at once,” as you put it, we can draw sounds out of it bit by bit. The idea behind this is that the grooves pass slowly under the needle, and as they pass, the needle vibrates slightly in response to those very fine designs you earlier referred to. Somehow, in those designs are coded musical sounds, which are processed and passed on to the loudspeaker, to dispense to our waiting ears. Thus we manage to hear the music just as you said, “a bit at a time.” The whole process is quite marvelous, I should say.

TORTOISE: Well, it is marvelously complicated, I’ll grant you that. But why don’t you do as I do—just hang the record up on your wall and enjoy its beauty all at once, instead of in small pieces doled out over a period of time? Is it that somehow there is a masochistic pleasure in the pain of doling out its beauties so slowly? I am always against masochism.

ACHILLES: Oh, you have totally misunderstood the nature of music, I am afraid. You see, it is in the nature of music to be spread out over a period of time. One doesn’t just enjoy it in one sudden burst of sound—it can’t be done, you see.

TORTOISE: Well, I suppose one wouldn’t like hearing one large piercing noise—the sum of all the parts—in one short blow. But why can’t you humans do as I do—it’s such a simple, obvious idea—hang the playing-record up on your wall and, with your eyes, take in all its pleasures at a glance! After all, they are all there, aren’t they?

ACHILLES: I am astonished to hear that you find the surface of one playing-record any different from that of any other. They all look alike to me—much as Tortoises do.

TORTOISE: Well! I hardly need dignify that comment with an answer. You know very well that they are just as different as, say, two pieces of music, one by Bach and the other by Beethoven.

ACHILLES: They look very similar to me.

TORTOISE: Well, it was you who allowed as how the very surfaces of the record contain all the music—thus if the two pieces of music differ so must the record surfaces differ—and to exactly the same amount as do the pieces, moreover.

ACHILLES: I guess you’ve got a point there.

TORTOISE: I’m glad you’ll grant me that. So, since all of the music is on the face of the record, why don’t you take it in at a glance, or at most a cursory once-over? It would certainly provide a much more intense pleasure. And you’ll have to grant that each part of the musical selection is in its proper place; the relationship of the parts is not lost, as it would be if all the sounds were to be heard at once.

ACHILLES: Well, in the first place, Mr. T, I don’t happen to have very good eyes, and—

TORTOISE: Aha! I’ve got another solution! Why don’t you paste all the pages of the written score of some selection upon your wall and regard its beauties from time to time, as you would a painting? Sure you’ll have to admit that the music is all there, in every last respect.

ACHILLES: Well, to tell the truth, Mr. T, I must confess to a shortcoming in my aesthetic capacities: I doubt that I would know how to visually interpret the printed symbols in front of me in such a way as to give me the same pleasure as I gain from the actual hearing.

TORTOISE: I am sorry indeed to hear that. Why, it could save you so much time! For imagine, instead of wasting a full hour listening to a Beethoven symphony, on waking up some morning you could simply open your eyes and take it all in, hanging there on your wall, in ten seconds or less, and be refreshed and ready for a fine, fulfilling day?

ACHILLES: Oh, you do poor Beethoven an injustice, Mr. T, a sorry injustice.

TORTOISE: Why, not at all. Beethoven is my second favorite composer. I have spent many long minutes gazing at his beautiful works, both in score and on playing record. The sculpted forms in some of his playing records are so exquisite, you have no idea.

ACHILLES: I must admit, you have floored me. That is an odd way, to put it mildly, to enjoy music. But I suppose you are an odd character, and this idiosyncrasy makes as much sense, given what I know of you any of the rest.

TORTOISE: A condescending view. How would you like it, if some friend “revealed” to you that you’d never correctly understood a Leonardo painting—in reality, it should be listened to, not looked at, and is sixty-two minutes long, in eight movements, and contains long passages with nothing but the loud ringing of many different-sized bells?

ACHILLES: That is an odd way to think of paintings. But…

TORTOISE: Did I ever tell you about my friend the alligator, who enjoys music while lying on his back in the sun?

ACHILLES: Not that I recall.

TORTOISE: He has the advantage of having no shell covering his belly. So whenever he wants to “hear” a lovely piece, he picks out the appropriate disk and slaps it sharply for an instant against his stomach. The ecstasy of absorbing so many luscious patterns all a once, he tells me, is indescribable. So just think—his experience is, as novel to me as mine is to you!

ACHILLES: But how can he tell the difference between one record and another?

TORTOISE: To him, slapping Bach and Beethoven against his belly are as different as to you slapping a waffle iron and a velvet pad against your bare back would be!

ACHILLES: In so turning the tables on me, Mr. T, you have shown me one thing—your point of view must be just as valid as mine—and if I did not admit it, I should be an auditory chauvinist pig.

TORTOISE: Well put—admirably put! Now that we have gone over our relative points of view, I will have to confess to being familiar with your way of listening to playing records, rather than looking at them, odd though it does seem to me. The comparison between the two types of experience was what inspired me to exploit this example as an analogy to what I wish to present to you now, Achilles.

ACHILLES: More of your usual trickery, I see. Well, go on with it—I’m all eyes.

TORTOISE: All right. Let’s suppose that I came to you one morning with a very big book. You’d say, “Hullo, Mr. Tortoise—what’s in that big book you’re carrying with you?” (if I’m not mistaken); and I’d reply “It’s a schematic description of Albert Einstein’s brain, down to the cellular level, made by some painstaking and slightly crazy neurologist after Einstein died. You know he bequeathed his brain to science, don’t you?” And you’d say, “What in the world are you talking about, ‘a schematic description of Albert Einstein’s brain, down to the cellular level’?” would you not?

ACHILLES: I certainly would! The notion sounds preposterous. I suppose you’d go on roughly as follows: “Probably you’re aware, Achilles, that a brain—any brain—is composed of neurons, or nerve cells, linked together by fibers called ‘axons’ to form a highly interconnected network.” I’d say interestedly, “Go on.” So you would.

TORTOISE: Bravo! You’re doing very well! You took the words right out of my mouth! So I would indeed go on, as you suggested. I’d continue, “The details are beside the point here, but a little knowledge is essential. These neurons are known to fire, which means that a minuscule electric current (regulated by the resistance of the axon) passes down an axon into an adjoining neuron, where it may join other signals in a combined effort to ‘trigger’ this neighbor-neuron to fire in turn. The neighbor, however, will cooperate only if the sum of the incoming currents has reached a threshold value (which is determined by its internal structure); otherwise it will refuse to fire at all.” At this point, you might say, “Hmm.”

ACHILLES: So how would you go on, Mr. T?

TORTOISE: A good question. I suppose I might say something like this: “The foregoing is a peanut-sized summary of the goings-on in a brain, but I suppose it’s sufficient background for an explanation of what this heavy book is that I’m carrying about with me today.” If I know you at all, you’d say, “Oh, I’m eager to hear about it, but perhaps I should be warier, lest it contain one of your infamous schemes, whereby you lure poor little unsuspecting me into one of your inescapable absurdities.” But I’d reassure you that no such prospect was in store, and thus reassured, you’d urge me to divulge the contents of the book, about which you, having taken a peek in it, might say, “It just looks like a lot of numbers and letters and little abbreviations and things!” And I’d say, “What did you expect? Little pictures of stars and galaxies and atoms, whirling about with formula such as ‘E = mc²’ scattered hither and thither?”

ACHILLES: At that swipe, I might take offense. I’d say indignantly, “Certainly not.”

TORTOISE: Of course you would—rightly so. And then you’d say, “Well, what are all those numbers and things? What do they stand for?”

ACHILLES: Let me go on. I can anticipate, I believe, just how you’d reply: “Each page of this book—and there are around a hundred billion numbered pages in it—corresponds to one neuron and contains numbers recording such aspects relevant to that neuron as: which other neurons its axons lead to, what its threshold current is for firing, and so on. However, I forgot to tell you certain further important facts about the functioning of brains in general—in particular what happens, or is believed to happen (from all we know from neurological research), when thoughts occur in the brain, and especially conscious thoughts.” I might object with some vaguely worded complaint about thoughts occurring in the mind, not the brain, but you’d hastily dismiss that remark and say, “We can talk about that some other time—say, for example, if we meet by chance in the Jardin du Luxembourg someday. But for now my goal is to explain the contents of this book to you.” I’d be placated, I suppose, as I usually am, so you’d press on with a comment in this vein: “A thought occurs (in the mind or the brain, whichever you prefer—for now!) when a series of connected neurons fire in succession—mind you, it may not be a long string of individual neurons firing like chain of dominoes falling down one after another—it may be more like several neurons at a time tending to trigger another few, and so forth. More likely than not, some stray neural chains will get started along the side of the mainstream but soon will peter out, as threshold currents are not attained. Thus, one will have, in sum, a broad or narrow squad of firing neurons, transmitting their energy to others in turn, thus forming a dynamic chain that meanders within the brain—its course determined by the various resistances in the axons that are encountered along the way. It would not be out of place to say that ‘the path of least resistance is followed,’ if you follow me.” At this point, I’d be sure to comment, “You’ve surely said a mouthful—let me have a moment to digest it.” After mulling over this food for thought you’d so far provided me with, and asking you a few clarifying questions on it, I’d be satisfied that I’d gotten the general picture. Of course you’d probably tell me that if I wanted more information on the subject, I could easily go look it up in almost any popular book about the brain. So then you’d say, “Let me wind up this description of neural activity by briefly describing what accounts for memory, at least as well as has been so far established. Think of the ‘flashing spot of activity’ careening around within the brain (‘where all the action is,’ so to speak) as a boat traveling across the surface of a pond, such as those toy sailboats that children sometimes bring to the octagonal ponds in the Jardin du Luxembourg, the site of our hypothetical mind-brain encounter; every boat leaves a disturbance behind it, its wake, as it travels through its medium. The ‘hot spot’ within the brain, just like the boat, leaves its own kind of disturbance, or wake, behind: the neurons that just fired as the signal came through continue to undergo some kind of internal activity—perhaps chemical in nature—for a few seconds. A permanent change in the neuron is thereby effected. The change is reflected in some of the numbers we have already spoken of, such as the threshold value for firing, the axon resistances, and so forth. The exact way in which those numbers are modified is, of course, dependent on certain aspects of the internal structure in question—and these aspects themselves are susceptible to numerical encoding.” I might well chime in at this point, I imagine, saying “Hence it would be of utmost importance to record those numbers for every neuron, as well as the already-mentioned resistances and thresholds.” You would no doubt reply, “An astute remark, Achilles; I had not anticipated you’d see that necessity so quickly. And we might do well to give those numbers a name too: the ‘structure-altering numbers’ seems adequate to me.” To conclude this exchange, I might make the following sort of remark: “The structure-altering numbers are quite remarkable in that they not only describe how other numbers on the page are to change, but also how they themselves are to change, next time the neural flash comes passing through!”

TORTOISE: Oh, you have captured quite well the essence of what might go on between the two of us in an admittedly hypothetical dialogue. I might well say all the words you attributed to me; and I have every reason to believe that you too could come forth with such utterances as you have just proposed. Thus, what have we come to? Ah, yes, I recall—in the hypothetical situation set up, I was in possession of a book, wherein were numerically recorded all the relevant data, neuron by neuron, taken from the brain of Albert Einstein the day of his death. On each page, we have: (1) a threshold value; (2) a set of page numbers, to indicate neurons linked to the present one; (3) the values of resistance of the linking axons; and (4) a set of numbers indicating how the wakelike “reverberations” of the neuron, which occur as a result of its firing, will alter any of the numbers on the page.

ACHILLES: By telling me what you have just said, you would have completed your aim of explaining to me the nature of the heavy tome in your possession. So we would probably have come to the end of our hypothetical dialogue, and I can imagine that we would soon thereafter bid each other adieu. Yet I cannot help making the observation that the reference you made in that hypothetical dialogue some possible future conversation in these gardens between the pair of us strikingly suggests the circumstances in which we find ourselves today!

TORTOISE: How coincidental! It surely is by pure chance.

ACHILLES: If you don’t mind, Mr. T, I’d like to know how this fictitious Einstein book could conceivably shed any light on the “mind-brain” problem. Could you oblige me in that respect?

TORTOISE: Willingly, Achilles, willingly. Would you mind, though, if I added a few extra features to the book, since it is hypothetical anyway?

ACHILLES: I can’t see why I should object at this point. If it’s already got a hundred billion pages or so, a few more can’t hurt.

TORTOISE: A sporting attitude. The features are as follows. When sound hits the ear, the oscillations set up within the drum are relayed to delicate structures within the middle and inner ear; these eventually connect to neurons whose duty it is to process such auditory information—thus we could call them “auditory neurons.” Likewise, there exist neurons whose duty it is to convey coded directions to any given set of muscles; thus, hand motions are caused by the firing of specific neurons in the brain linked indirectly to the muscles in the hand. The same can be said of the mouth and vocal cords. As our additional information, then, for the book, we’d like to have whatever set of data is required to know precisely how the auditory neuron will be excited by a given incoming tone, if we supply its pitch and loudness. And the other essential chapter in the book is the one that tells in what way the firing of any “mouth-directing neuron” or “vocal-cord-directing neuron” will affect the muscles of the organ in question.

ACHILLES: I see what you mean. We’d like to know how the internal structure of neurons was affected by any auditory input signal; and also how the firing of certain key neurons, linked to speech organs, would affect those organs.

TORTOISE: Precisely. You know, sometimes, Achilles, it’s good to have you around to bounce my ideas off of—they come back at me considerably cleaner than when I came out with them. Your naïve simplicity somehow complements my learned verbosity.

ACHILLES: I’d like to bounce that one off on you, Mr. T.

TORTOISE: How’s that? What do you mean? Did I say something untoward?

ACHILLES: Now, Mr. T, I assume that in the heavy tome under discussion, there would be numerical conversion tables, which accomplish precisely the tasks just set forth. They would give the neural response of each auditory neuron to any tone; and they would give the changes in mouth shape and vocal-cord tension as a function of the neurons linked to them by nerves in Einstein’s body.

TORTOISE: Right you are.

ACHILLES: How could such an extensive documentation of Einstein do anybody any good?

TORTOISE: Why, it could do no good for anyone, except conceivably some starving neurologist.

ACHILLES: So why have you proposed this stupendous volume, this prodigious opus?

TORTOISE: Why, only to tickle my fancy as I mused on mind and brain. But it may serve as a lesson to novices in the field.

ACHILLES: Am I one?

TORTOISE: Doubtless. You’ll do very well as a test subject in illustrating the merits of such a book.

ACHILLES: I somehow can’t help wondering what old Einstein would think of it all.

TORTOISE: Why, given the book, you could find out.

ACHILLES: I could? I would not know where to begin.

TORTOISE: You would begin by introducing yourself.

ACHILLES: To whom? To the book?

TORTOISE: Yes—it’s Einstein, isn’t it?

ACHILLES: No, Einstein was a person, not a book.

TORTOISE: Well, that’s a matter for some consideration, I’d say. Didn’t you say that there is music stored in playing-records?

ACHILLES: I did, and what’s more, I described to you how to get at it. Instead of a playing-record being there “all at once,” we can use an appropriate needle and other apparatus and extract real, living music from it, which emerges “a bit at a time” just like real music.

TORTOISE: Are you implying that it is only some kind of synthetic imitation?

ACHILLES: Well, the sounds are genuine enough.... They did come off plastic, but the music is made of real sounds.

TORTOISE: And yet it’s there “all at once” too, isn’t it—as a disk?

ACHILLES: As you pointed out to me earlier, yes, it is.

TORTOISE: Now you might at first say that music is sounds, not a record, mightn’t you?

ACHILLES: Well, yes, I would; yes.

TORTOISE: Then you are very forgetful! Let me recall to you that to me, music is the record itself, which I can sit and tranquilly admire. I don’t presume to tell you that to see Leonardo’s Madonna of the Rocks as a painting is to miss the point, do I? Do I go around claiming that that painting is only a storage place for long, droning bassoon blasts, melodious piccolo runs, and stately harp dances?

ACHILLES: Why, no, you don’t. I guess that either way, we respond to some of the same features of playing-records, even if you like their visual aspect, while I prefer their auditory aspect. At least, I hope that what you like in Beethoven’s music corresponds to what I like.

TORTOISE: May or may not. Personally, I don’t care. Now, as to whether Einstein was a person, or is in the book.... You should introduce yourself and see.

ACHILLES: But a book can’t respond to a statement—it’s like a black piece of plastic: It’s there “all at once.”

TORTOISE: Perhaps that little phrase will serve as a clue to you. Consider what we just said on the subject of music and playing-records.

ACHILLES: You mean, I should try to experience it “a bit at a time”? What bit should I begin at? Should I start at page 1 and read straight on through, to the end?

TORTOISE: Unlikely. Suppose you were going to introduce yourself to Einstein—what would you say?

ACHILLES: Ah… “Hullo, Dr. Einstein. My name is Achilles.”

TORTOISE: Splendid. Now there are some fine tones of sound for you.

ACHILLES: Tones… hmmm. Are you planning to use those conversion tables?

TORTOISE: Good gracious, what a brilliant thought. Why didn’t it occur to me?

ACHILLES: Well, everybody has inspirations once in a while, you know. Don’t feel too bad.

TORTOISE: Well, you came up with a good thought. That’s just what we’d try to implement, had we the book.

ACHILLES: So, you mean, we’d look up the possible changes in Einstein’s auditory neuron structure resulting from each tone of the utterance?

TORTOISE: Well, roughly. You see, we’d have to do it very carefully. We’d take the first tone, as you suggested, and see which cells it would make fire, and how. That is, we’d see precisely how each number on each page would change. Then we’d go through the book painstakingly page by page, and actually effect those changes. You might call that “round one.”

ACHILLES: Would round two be a similar process occasioned by the second tone?

TORTOISE: Not quite. You see, we haven’t completed the response to the first tone yet. We’ve gone through the book once, neuron by neuron. But there is the fact that some of the neurons are firing, you know, so we have to take that into account. Which means we have to proceed to the pages where their axons lead and modify those pages in the way that is directed by the “structure-changing numbers.”That is round two. And those neurons, in turn, will lead us to still others, and lo and behold, we’re off on a merry loop around the brain.

ACHILLES: Well, when do we ever come to the second tone?

TORTOISE: Good point. It’s something I neglected to say earlier. We need to establish a kind of time scale. Perhaps on each page the time taken for the neuron in question to fire is specified—the time it took to fire in real life, in Einstein’s brain—a quantity best measured, probably, in thousandths of a second. As the rounds progress, we sum up all the firing times, and when the times add up to the length of the first tone, we start in on the second tone. That way, we can proceed to feed in tone after tone of your self-introductory utterance, modifying the neurons that would respond to that utterance at every step along the way.

ACHILLES: An interesting procedure. But surely a very lengthy one.

TORTOISE: Well, as long as it is all hypothetical, that should not bother us in the least. It would probably take millennia, but let’s just say five seconds, for the sake of argument.

ACHILLES: Five seconds required to feed in that utterance? All right. So right now, my picture is that we have altered scores, if not myriads, of pages in that book, changing numbers, on page after page after page, wherever we were led, either by the previous pages or by the tones that we were feeding in, via the auditory conversion tables.

TORTOISE: Right. And now, once the utterance is finished, neurons continue to fire—from one to the next, the cascade continues—so we perform a strange and elaborate “dance,” shuffling back and forth between pages, round after round, without having any auditory input to bother with.

ACHILLES: I can see that something strange is about to happen. After another few “seconds” (if we are to stick to that somewhat ridiculous underestimate) of page turning and number changing, certain of the “speech neurons” will begin to fire. And we would then do well to consult the tables indicating shape of mouth or tension in vocal cords.

TORTOISE: You have caught wind of what is happening, Achilles. The way to read the book is not from page 1, but according to the directions in the preface, which tell about all the changes that must be effected and give all the rules for how to proceed.

ACHILLES: I suppose that given mouth shape and condition of vocal cords, it would be within grasp to determine what Einstein is “saying,” wouldn’t it? Especially given the level of technical advancement we’ve presupposed, that seems only a minor task. So I suppose he would say something to me.

TORTOISE: I presume so—such as, “Oh, hello. Did you come to visit me? Have I died?”

ACHILLES: That is a strange question. Of course he did.

TORTOISE: Well, then who’s asking you the question?

ACHILLES: Oh, just some silly book. It’s not Einstein, of course! You can’ trap me into saying that!

TORTOISE: I wouldn’t dream of it. But perhaps you’d like to address some more questions to the book. You could conduct a whole conversation, if you had the patience.

ACHILLES: That is an exciting prospect—I could see just what Einstein would have said in conversations with me, if I’d ever really met him!

TORTOISE: Yes, you could begin by asking how he felt; then proceeding to a description of how glad you were to meet him, since you’d never had the chance during his lifetime—proceeding just as if he were the “real” Einstein, which, of course, you’ve already decided was out of the question. How do you suppose he would react, when you told him he’s not the real Einstein?

ACHILLES: Now, hold on a minute—you’re employing the pronoun “he” about a process combined with a huge book. That’s no “he”—it’s something else. You’re prejudicing the question.

TORTOISE: Well, you would address him as Einstein as you fed in questions, wouldn’t you? Or would you say, “Hullo, book-of-Einstein’s brain-mechanisms, my name is Achilles”? I think you would catch Einstein off guard if you did that. He’d certainly be puzzled.

ACHILLES: There is no “he.” I wish you’d quit using that pronoun.

TORTOISE: The reason I’m using it is that I’m simply imagining what you would have said to him, had you actually met him in his hospital bed in Princeton. Certainly you should address questions and comments to the book in the same fashion as you would have to the person Einstein, shouldn’t you? After all, the book initially reflects how his brain was on the last day of his life—and he regarded himself as a person then, not a book, didn’t he?

ACHILLES: Well, yes. I should direct questions at the book as I would have to the real person had I been there.

TORTOISE: You could explain to him that he had, unfortunately, died, but that his brain had been encoded in a mammoth catalogue after his death, which you are now in possession of, and that you are conducting your conversation by means of that catalogue and its conversion tables for speech.

ACHILLES: He’d probably be most astonished to hear that!

TORTOISE: Who? I thought there was no “he”!

ACHILLES: There is no “he” if I’m talking to the book—but if I told it to the real Einstein, he’d be surprised.

TORTOISE: Why would you be telling a live person to his face that he had already died, that his brain had been encoded in a catalogue, and that you were conducting your conversation with him through that catalogue?

ACHILLES: Well, I wouldn’t tell it to a live person, I’d tell it to the book, and find out what the live person’s reactions would have been. So, in a way, “he” is there. I am beginning to be puzzled… who am I talking to in that book? Is there somebody alive because it exists? Where are those thoughts coming from?

TORTOISE: From the book. You know that very well.

ACHILLES: Well, then, how can he say how he’s feeling? How does a book feel?

TORTOISE: A book doesn’t feel any way. A book just is. It’s like a chair. It’s just there.

ACHILLES: Well, this isn’t just a book—it’s a book plus a whole process. How does a book plus a process feel?

TORTOISE: How should I know? But you can ask it that question yourself.

ACHILLES: And I know what it’ll say: “I’m feeling very weak and my legs ache,” or some such thing. And a book, or a book-plus-process, has no legs!

TORTOISE: But its neural structure has incorporated a very strong memory of legs and leg-aching. Why don’t you tell it that it’s now no longer a person, but a book-plus-process? Maybe after you’ve explained that fact in about as much detail as you know it, it would start to understand that and forget about its leg-aching, or what it took for leg-aching. After all, it has no vested interest in feeling its leg, which it doesn’t have, aching. It might as well ignore such things and concentrate on what it does have, such as the ability to communicate with you, Achilles, and to think.

ACHILLES: There is something frightfully sad about this whole process. One of the sadder things is that it would take so much time to get messages in and out of the brain, that before I’d completed many exchanges, I’d be an old man.

TORTOISE: Well, you could be turned into a catalogue too.

ACHILLES: Ugh! And not have any legs left, to run footraces? No thank you!

TORTOISE: You could be turned into a catalogue and continue your thought-provoking conversation with Einstein, as long as someone were managing your book, flipping pages and writing numbers in it. Even better, you could conduct several conversations at once. All we need do is make several copies of the Achilles catalogue, including directions for use, and send it around to whomever you desired. You’d enjoy that.

ACHILLES: Ah, now, that’s more exciting. Let’s see—Homer, Zeno, Lewis Carroll… provided that catalogues had been made of their brains, as well. But wait a minute. How am I going to keep track of all those conversations at once?

TORTOISE: No trouble—each one’s independent of the others.

ACHILLES: Yes, I know—but I’ve still got to keep them in my head all at once.

TORTOISE: Your head? You would have no head, remember.

ACHILLES: No head? Then where would I be? What is going on here?

TORTOISE: You’d be at all those different places at once, conversations with all those people.

ACHILLES: How would it feel to be conducting conversations with several people at a time?

TORTOISE: Why don’t yon just imagine what it would be like to ask Einstein, presuming, of course, that you had made several copies of his catalogue, and shipped them about to various of your friends, or anyone, for that matter, and they too were talking with him.

ACHILLES: Well, if I didn’t tell the Einstein in my possession about it, he’d have no way to know of the other catalogues or conversations. After all, each catalogue has no way of being influenced by any of the other catalogues. So I guess he’d just say that he certainly didn’t feel like he was engaging in more than one discussion at a time.

TORTOISE: So that’s how you’d feel too, if several of you were engaging in simultaneous conversations.

ACHILLES: I? Which one would be me?

TORTOISE: Any of them: all of them; or perhaps, none of them.

ACHILLES: This is eerie. I don’t know where I would be—if anywhere. And all of those weird catalogues would be claiming to be me.

TORTOISE: Well, you should expect as much: you do it yourself, don’t you? Why, I could even introduce a pair of you—or all of you—to each other.

ACHILLES: Uh-oh. I was waiting for this moment. Every time I see you, you spring something like this on me.

TORTOISE: There just might ensue a teeny scrap over which one was the real one, don’t you think so?

ACHILLES: Oh, this is a diabolical scheme to squeeze the juice out of the human soul. I’m losing a clear sight of who “I” is. Is “I” a person? A process? A structure in my brain? Or is “I” some uncapturable essence that feels what goes on in my brain?

ACHILLES: An interesting question. Let us go back to Einstein, to examine it. Did Einstein die, or was he kept on living by the creation of the catalogue?

ACHILLES: Well, to all appearances, some part of his spirit was kept alive by the fact that the data were recorded.

TORTOISE: Even if the book never was used? Would he be alive then?

ACHILLES: Oh, that’s a difficult one. I guess I’d have to say “no.” Clearly what made him live on was the fact that we “brought him to life” from out of the sterile book, “a bit at a time.” It was the process, above and beyond the mere data book. He was conversing with us, that’s what made him alive. His neurons were firing, in a somewhat figurative way, albeit rather slowly compared to their usual speed—but that’s of no consequence, as long as they were firing.

TORTOISE: Supposing it took you ten seconds to do round one, a hundred seconds to do round two, a thousand seconds to accomplish round three, and so forth. Of course, the book would not know how long all this took, because its only contact with the outside world is through its auditory conversion tables—and in particular, it can never know anything that you don’t choose to tell it. Would it still be as alive, despite the enormous sluggishness of its firing after a few rounds?

ACHILLES: I don’t see why not. If I too had been catalogued in the same way and my pages were being flipped equally lethargically, our rates of conversation would be matched. Neither he nor I would have cause to feel any abnormality in the conversation, even if, in the outer world, our mere exchange of greetings lasted millennia.

TORTOISE: You at first spoke of this process that brings out the structure “a bit at a time” as being so important, yet now it seems it doesn’t matter if it’s constantly slowing down. Eventually the rate of exchange of thoughts would be a syllable a century. And after a while, one neuron would fire every trillion years. Not exactly a sparkling conversation!

ACHILLES: Not in the outer world, no. But to the two of us, who are unaware of the passage of time in the outer world, all is well and normal, as long as someone does our internal bookwork—no matter how slowly. Einstein and I are serenely oblivious to the fast-changing world outside our flipping pages.

TORTOISE: Suppose this faithful neural clerk—let’s call him A-kill-ease, just for fun (no relation to present company, of course)—just suppose he slipped off one afternoon for a little nip, and forgot to come back....

ACHILLES: Foul play! Double homicide! Or do I mean bibliocide?

TORTOISE: Is it all that bad? Both of you are still there, “all at once.”

ACHILLES: “All at once,” bah! What’s the fun of life if we’re not being processed?

TORTOISE: Was it any better at an ever-slowing snail’s pace?

ACHILLES: At any pace, it’s better. Even a Tortoise’s. But say—what’s the point of calling the book-tender “A-kill-ease”?

TORTOISE: I just thought I’d let you think about how it would feel if your brain were not only encoded in a book, but also you were minding that very brain-book (no pun intended, to be sure!).

ACHILLES: I suppose I would have to ask my own book. Or no—wait a minute. My book would have to ask me! Oh, I’m so befuddled by these confounded and compounded level-confusions you always hit me with out of the blue! Ah! I have a grand idea. Suppose there was a machine that came along with the books, a machine that does the page turning, the little calculations, and the clerical work. This way we would avoid the problem of human unreliability, as well as your strange twisty loop.

TORTOISE: Suppose so—an ingenious plan. And suppose the machine broke.

ACHILLES: Oh, you have a morbid imagination! What recherché tortures you would put me through!

TORTOISE: Not at all. Unless somebody told you of it, you wouldn’t even be aware of the machine’s existence, much less that the machine had broken.

ACHILLES: I don’t like this isolation from the outer world. I’d rather have some way of sensing what’s going on around me than be dependent upon people telling me things of their own choice. Why not take advantage of the neurons which, in life, processed visual input? Just like the auditory conversion tables, we could have optical conversion tables. These will be used to create changes in the book according to the signals from a television camera. Then I could watch the world about me, and react to its events. In particular, I’d soon become aware of the page-turning machine, the book full of so many pages and numbers, and so on....

TORTOISE: Oh, you are determined to suffer. So now you’ll perceive the fate that is to befall you: You’ll “see,” by means of input fed into you via the television camera and the conversion tables, that the mechanical page-turner that has served you so well has a loose part that is just about to slip. That’ll scare you, all right. And what good is that? If you had no optical scanning device, you’d have no way of knowing what’s going on in the world about you, not even with respect to your page-turner. Your thoughts proceed calmly and coolly, unaffected by the cares of the outside world, blithely unaware that they may soon come to a forced end, since the page-turner may break. An idyllic existence! Up until the very end, not a worry!

ACHILLES: But when it breaks, I would be dead and gone.

TORTOISE: You would?

ACHILLES: I’d be a lifeless, motionless heap of number-covered sheets.

TORTOISE: A pity, I’m sure. But maybe old A-kill-ease would somehow find his way back to his familiar haunts, and take up where the broken machine left off.

ACHILLES: Oh! So I’d be resuscitated. I was dead for a while, and then returned to life!

TORTOISE: If you insist on making these strange distinctions. What makes you any “deader” when the machine breaks than you are when A-kill-ease leaves you unattended for a few minutes or a few years, to play a game of backgammon, to take a trip around the world, or to go get his brain copied into a book?

ACHILLES: I’m obviously deader when the machine breaks, because there is no expectation that I will ever resume functioning… whereas when A-kill-ease takes off on his sprees, he will eventually return to his duty.

TORTOISE: You mean, if you have been abandoned, you are still alive, just because A-kill-ease has the intention of returning? But when the machine breaks, you are dead?

ACHILLES: That would be a very silly way of defining “aliveness” and “deadness.” Certainly such concepts should have nothing to do with the mere intentions of other beings. It would be as silly as saying that a light bulb is “dead” if its owner has no intention of turning it on again. Intrinsically, the light bulb is the same as ever—and that’s what counts. In my case, what counts is that that book should be kept intact.

TORTOISE: You mean, that it should all be there, all at once? Its mere presence there is what guarantees your aliveness? Just as the existence of a playing-record is tantamount to the existence of its music?

ACHILLES: A funny image comes into my head. The earth is destroyed, but one record of Bach’s music somehow escapes and goes sailing out into the void of space. Does the music still exist? It would be silly to make the answer depend upon whether it is ever found and played by some humanlike creature—wouldn’t it? To you, Mr. T, the music exists as the record itself. Similarly, when we come back to that book, I feel that if the book merely sits there, all at once, I’m still there. But if that book is destroyed, I’m gone.

TORTOISE: You maintain that as long as those numbers and conversion tables are in existence, you are essentially, potentially alive?

ACHILLES: Yes; that’s it. That’s what’s all important—the integrity of my brain structure.

TORTOISE: Do you mind if I just ask, “Suppose someone absconded with the instructions in the preface, telling how to use the book?”

ACHILLES: Well, they’d better bring them back, is all I can say. My goose would be cooked if they weren’t going to return those instructions. What good’s the book without its instructions?

TORTOISE: Once again you are saying that the question as to whether you are alive depends on whether the filcher has good intentions or bad. It could just as well have been the capricious wind, blowing about, which caught hold of those few pages of preface and wafted them into the air. Now there’s no question of intention. Would “you” be less alive for that?

ACHILLES: This is a little tricky. Let me go over the question slowly. I die; my brain is transcribed into a book; the book has a set of instructions telling how to process the book’s pages in a way that parallels how my neurons fire in my actual brain right now.

TORTOISE: And the book, together with its instructions, lies on a dusty shelf in a far corner of a used book store. A chap comes in and chances upon the oddity. “Egads!” he exclaims, “An Achilles-book! What on earth could that be? I’ll buy it and try it!”

ACHILLES: He should be sure to buy the instructions too! It is essential that the book and instructions remain together.

TORTOISE: How close? In the same binding? In the same bag? In the same house? Within a mile of each other? Is your existence somehow diminished if the pages are scattered hither and thither by a breeze? At what precise point would you feel the book had lost its structural integrity? You know, I appreciate a warped playing-record fully as much as a flat one. In fact, it’s got an extra bit of charm, to the cultured eye. Why, I have a friend who considers broken records more stylish than the originals! You should see his walls—they’re plastered with broken Bach-fragmented fugues, crushed canons, ruptured ricercari. He delights in it. Structural integrity is in the eye of the beholder, my friend.

ACHILLES: Well, as long as you’re asking me to be the beholder, I’d say that if the pages are to be reunited, there is still hope for my survival.

TORTOISE: Reunited in whose eyes? Once you’re dead, you the beholder remain only in book form (if at all). Once the book’s pages start being scattered, will you feel yourself losing structural integrity? Or, front the outside, once I feel that the structure is irretrievably gone, should I conclude that you no longer exist? Or does some “essence” of you exist still, in scattered form? Who will judge?

ACHILLES: Oh, goodness. I have totally lost track of the progress of that poor soul inside the book. And as to what he himself—or I myself—would be feeling, I am even more unsure.

TORTOISE: “That poor soul inside the book”? Oh, Achilles! Are you still clinging to that old notion that it’s “you” somehow there, inside that book? If I am correct in my memory, you were so reluctant at first to accept that kind of idea when I suggested that you really were talking to Einstein himself.

ACHILLES: Well, I was reluctant until I saw that it—the book—seemed to feel, or at least to express, all his—Einstein’s—emotions, or what seemed like emotions. But maybe you’re right to chide me—maybe I should just trust the old, familiar commonsense view that the only real “I” is right here, inside my very own living, organic brain.

TORTOISE: You mean, the old, familiar “ghost-inside-the-machine” theory, is that it? What is it, inside there, that this “you” is?

ACHILLES: It’s whatever feels all these emotions that I express.

TORTOISE: Maybe the feeling of those emotions is the sheer physical event of having a shower of electrochemical activity come flying through some one of the various neural pathways inside your brain. Maybe you use the word “feeling” to describe such an event.

ACHILLES: That sounds wrong, because the book uses the word “feeling,” if I do, and yet it can feel no electrochemical activity surging. All that the book “feels” is its numbers changing. Perhaps “feeling” is synonymous with the existence of any kind of neural activity, simulated or otherwise.

TORTOISE: Such a view would place undue stress on the unfolding of feeling “a bit at a time.” While the time development of a neural structure undoubtedly seems to us like the essence of feeling, why could it not be that feelings, like playing-records and paintings, are there “all at once”?

ACHILLES: The difference I can immediately spot between a playing-record of a piece of music, and a mind, is that the former does not change by evolving “a bit at a time”; but a mind, in its interaction over a span of time with the exterior world, gets modified a way that was not originally inherent in its physical structure.

TORTOISE: You have a good point. A mind, or brain, interacts with t world and thus is subject to change that one cannot predict by knowing the structure of the brain alone. But this does not in any way diminish the “aliveness” of said mind, when it introspectively ponders some thought, without any interference from without. During such a period of introspection, the changes it undergoes are inherent in it. Though it is evolving “a bit at a time,” it is inherently there “all at once.” I can clarify what I mean by drawing a parallel to a simpler system. The entire path of a thrown grapefruit is inherent once the grapefruit is released. Watching the fruit in flight is one way—the usual way—of experiencing its motion; it could be labeled the “bit-at-a-time” picture of its motion. But just knowing its initial position and velocity is another equally valid way of experiencing the motion; this picture of the motion could be labeled the “all-at-once” picture. Of course, in this picture we assume no interference by passing storks and so forth. A brain (or a brain catalogue) shares this dual nature; as long as it is not interacting with the exterior world a being modified in ways foreign to it, its time development can viewed either in the “bit-at-a-time” picture or in the “all-at-once” picture. The latter picture is one that I advocate and that I thought you had come to agree with, when you described the record sailing out into space.

ACHILLES: I see things so much more easily in the “bit-at-a-time” picture.

TORTOISE: Of course you do. The human brain is set up to see that that way. Even in a simple case, like the motion of a flying grapefruit the brain is more satisfied to see the actual motion “a bit at a time” than it is to visualize a parabola “all at once.” But simply coming to recognize that there is an “all-at-once” picture was a great step by the human mind, because it amounted to the recognition that so regularities exist in nature, regularities that guide events in predictable channels.

ACHILLES: I recognize that feeling exists in the “bit-at-a-time” picture. I know this because that is how I feel my own feelings. But does it also exist in the “all-at-once” picture? Are there “feelings” in a motionless book?

TORTOISE: Is there music in a motionless playing-record?

ACHILLES: I am not sure any longer how to answer that question. But I still want to learn if “I” am in the Achilles book, or if the “real Einstein” is in the Einstein book.

TORTOISE: So you may; but for my part, I still want to learn if “you” are anywhere at all. So let us stick to the comfortable “bit-at-a-time” picture, and imagine the internal processes of your brain, Achilles. Imagine the “hot-spot,” that infamous shower of electrochemical activity, as it zigzags its way along the “path of least resistance.” You, Achilles, or what you refer to as “I,” have no control over which path is the one of least resistance.

ACHILLES: I don’t? Is it my subconscious, then? I know I sometimes feel my thoughts “spring up” to me as if motivated by subconscious tendencies.

TORTOISE: Perhaps “subconscious” is a good name for neural structure. It is, after all, your neural structure that, at any moment, determines which path is the one of least resistance. And it is because of that neural structure that the “hot-spot” follows that curlicue path and none other. This swirling electrochemical activity constitutes the mental and emotional life of Achilles.

ACHILLES: A weird and mechanistic song, Mr. T. I bet you could make it sound even stranger. Wax lyric if you can; let the verbs have their fling! Of Brain, Mind, and Man, let’s hear the Tortoise sing!

TORTOISE: Your verse is surely inspired by the gods, my dear companion. The brain of Achilles is like a labyrinth of rooms; each room has many doors leading to other rooms—and many of the rooms are labeled. (Each “room” may be thought of as a complex of a few or a few dozen neurons—perhaps more; and “labeled” rooms are special complexes composed mostly of speech-neurons.) As the “hot spot” tears through this labyrinth, flinging open and slamming shut doors, from time to time it enters a “labeled” room. At that point your throat and mouth contract: you say a word. All the while the neural flash loops relentlessly along its Achillean path, in shapes stranger than the dash of a gnat-hungry swallow; every twist, every turn is foreordained by the neural structure present in your brain, until sensory input messages interfere; then the flash veers away from the path it would have followed. And so it goes—room after room after labeled room is visited. You are speaking.

ACHILLES: I don’t always speak. Sometimes I merely sit and think.

TORTOISE: Granted. The labeled rooms may have their lights turned low—a sign for non-utterance: you don’t speak the words aloud. A “thought” occurs, silently. The hot spot continues—depositing, at door after door, either a drop of oil on the hinge to loosen it, or a drop of water to corrode it. Some doors have such rusty hinges they can’t be opened. Others are so often oiled they nearly open by themselves. Thus traces of the present are deposited for the future: the “I” of now leaves messages and memories for the “I” of a time to come. This neural dance is the dance of the soul; and the sole choreographer of the soul is physical law.

ACHILLES: Normally, I think that I’m in control of what I think; but the way you put it turns it all around backward, so that it sounds like “I” am just what comes out of all this neural structure and natural law. It makes what I consider myself sound at best like a by-product of an organism governed by natural law and, at worst, like an artificial concept produced by my distorted perspective. In other words, you make me feel as if I don’t know who—or what—I am, if anything.

TORTOISE: This is a very important matter to bring up. How can you “know” what you are? First of all, what does it mean to know something, anything, at all?

ACHILLES: Well, I presume that when I know something—or when, should I say, my brain knows something—there is a path that snakes through my brain, running through rooms, many of which are labeled. If I ever think a thought about the subject, my neural flash swishes along that path quite automatically, and if I am conversing, each time it passes through a labeled room, a sound of some type comes out. But of course I don’t need to think about my neural flash for it to do this very competently. It seems as if I function quite well without me!

TORTOISE: Well, it’s true that the “path of least resistance” does take care of itself quite well. But we can equate the result of all this functioning with you, Achilles. You needn’t feel that your self is dispensed with in this analysis.

ACHILLES: But the trouble with this picture is that my “self” is not in control of myself.

TORTOISE: I suppose it depends upon what you mean by “control,” Achilles. Clearly you cannot force your neural flash to deviate from the path of least resistance; but the Achilles of one moment is directly affecting what will become the path of least resistance in the next moment. That should give you some feeling that “you,” whatever you are, have some control over what you will feel and think and do, in the future.

ACHILLES: Well, yes, that is an interesting way to look at it, but it still means that I can’t just think whatever I want to think, but only what was set up for me to think, by an earlier version of me.

TORTOISE: But what is set up in your brain is what you want to think about, to a large degree. But sometimes, admittedly, you can’t make your brain function as you will it to. You forget someone’s name; you can’t concentrate on something important; you become nervous despite your best attempts to control yourself; all of this reflects what you said: that in a sense your “self” is not in control of yourself. Now it is up to you whether or not you wish to identify the Achilles of now with the Achilles of bygone times. If you do choose to identify with your former selves, then you can say that “you”—meaning the you that used to exist—are in control of what you are today; but if you prefer to think of yourself as existing solely in the present, then indeed it is true that what “you” do is under control of natural law and not under control of an independent “soul.”

ACHILLES: I am beginning to feel through this discussion that I “know” myself a little better. I wonder if it would be possible for me to learn all about my neural structure—so much so that I would be able to predict the path of my neural flash before it even covered its path! Surely, this would be total, exquisite self-knowledge.

TORTOISE: Oh, Achilles, you have innocently thrown yourself into the wildest of paradox, without the benefit of even the slightest coaching on my part! Maybe one day you will learn to do this regularly; then you will be able to dispense with me entirely!

ACHILLES: Enough of your mockery! Let’s hear about this paradox I’ve inadvertently fallen into.

TORTOISE: How could you learn all about yourself? You might try reading the Achilles book.

ACHILLES: That would certainly be a phenomenal project. A hundred billion pages! I’m afraid I’d fall asleep listening to myself read. Or—horrors—I might even die before I had completed the task! But suppose I were a very fast reader and managed to learn the contents of the whole book within the time allotted to me on the surface of our green sphere.

TORTOISE: So now you’d know all about Achilles—before he read the Achilles book! But you are quite ignorant about the Achilles who exists now!

ACHILLES: Oh, what a quandary! The fact that I read the book makes the book obsolete. The very attempt to learn about myself changes me from what I was. If only I could have a bigger brain, capable of digesting all of the complexity of myself. Yet I can see that even that would be of no avail, for possession of a bigger brain would make me all the more complex yet! My mind simply can’t understand all of itself. All I can know is the outline, the basic idea. Beyond a certain point, I cannot go. Although my brain structure is right there in my head, exactly where “I” am, still its nature is not accessible to this “I.” The very entity that constitutes “I”—and I am of necessity ignorant of it. My brain and “I” are not the same!

TORTOISE: A droll dilemma—the stuff of life’s many hilarities. And now, perhaps, Achilles, we can pause to ponder one of the original questions that prompted this discussion: “Do thoughts occur in the mind, or in the brain?”

ACHILLES: By now, I hardly know what is meant by “mind”—except, of course, as a sort of poetic expression for the brain, or its activities. The term reminds me of “beauty.” It is not something that one can locate in space—yet it is not hovering in an ethereal otherworld, either. It is more like a structural feature of a complex entity.

TORTOISE: Where lies the beauty, if I may rhetorically ask, of an étude by Scriabin? In the sounds? Among the printed notes? In the ear, mind, or brain of the beholder?

ACHILLES: It seems to me that “beauty” is just a sound that we utter whenever our neural flash passes through a certain region of our brains—a certain “labeled room.” It is tempting to think that to this sound there corresponds an “entity,” some kind of “existing thing.” In other words, because it is a noun, we think of beauty as a “Thing”; but maybe “beauty” denotes no Thing at all; the word is just a useful sound which certain events and perceptions make us want to pronounce.

TORTOISE: I would go further, Achilles: I would surmise that this is a property of many words—especially words like “beauty,” “truth,” “mind,” and “self.” Each word is but a sound which we are caused to utter, at various times, by our swooping, careening neural flash. And to each sound, we can hardly help but believe that there corresponds an Entity—a “Real Thing.” Well, I will say that the benefit that one derives from using a sound imbues it with a proportionate amount of what we call “meaning.” But as to whether that sound denotes any Thing… how would we ever know that?

ACHILLES: How solipsistically you view the universe, Mr. T. I thought such views were highly unfashionable in this day and age! One is supposed to consider that Things have an Existence of their own.

TORTOISE: Ah, me, yes, perhaps they do—I never denied it. I suppose it’s a pragmatic view of the meaning of “meaning,” useful in the bustle of everyday life, to make the assumption that some sounds do stand for Existing Entities. And the pragmatic value of this assumption may be its best justification. But let’s get back to the elusive site of the “real you,” Achilles!

ACHILLES: Well, I’m at a loss to say if it’s anywhere at all, even though another part of me is practically jumping to shout, “The ‘real me’ is here now.” Maybe the whole point is that whatever mechanism makes me make everyday statements like “Spades are trump” is quite like the mechanism which makes me—or the Achilles book—say sentences such as “The ‘real me’ is here now.” For certainly if I, Achilles, could say it, so could the book version of me—in fact, it would undoubtedly do so. Though my own first reflex is to affirm, “I know I exist; I feel it,” maybe all these “feelings” are just an illusion; maybe the “real I” is all an illusion; maybe, just like “beauty,” the sound “I” denotes no Thing at all, but is just a useful sound that we on occasion feel compelled to pronounce because our neural structures are set up that way. Probably that is what is happening when I say “I know I’m alive” or similar things. This would also explain why I got so puzzled when you brought up the version in which several copies of the Achilles book would be distributed to various people, and “I” would have conversations with all of them at once. I demanded to know where the “real I” was, and how “I” could take care of several conversations at once; I see now that each copy of the book has that structure built into it, that makes it automatically make pronouncements such as “I am the real me; I am feeling my own emotions and anybody else who claims to be Achilles is a fraud.” But I can see that the mere fact that it utters such things doesn’t mean that it has “real feelings”; and perhaps even more to the point, the mere fact that I, Achilles, utter such things, doesn’t really mean I am feeling anything (whatever that would mean!). In the light of all this, I am beginning to doubt if such phrases have any meaning at all.

TORTOISE: Well, of course, utterances about “feeling” one way or another are very useful, in practical terms.

ACHILLES: Oh, without doubt —I shan’t shun them just because this conversation has taken place; nor shall I shun the term “I,” as you can see for yourself. But I won’t imbue it with such “soulful” meaning as I have heretofore tended to do, rather instinctively, and, I have to say, dogmatically.

TORTOISE: I am glad that for once we seem to be in agreement in our conclusions. I see that the hour is growing late; dusk is approaching—just the time when all my forces seem to gather, and I feel quite energetic. I know you must have been disappointed by the “no-show” of your friend; how’s about a little footrace back to the fifth century B.C.?

ACHILLES: What a capital idea! But just to be fair, I’ll give you a head start of, oh, three centuries, since I’m so fleet of foot.

TORTOISE: You’re a mite cocky, Achilles.... You may not find it so easy to catch up with an Energetic Tortoise.

ACHILLES: Only a fool would bet on a slow-footed Tortoise, racing against me. Last one to Zeno’s house is a monkey’s uncle!

Reflections

“Well, all these fantasies have been fun, but they can’t really tell us anything. They’re just so much science fiction. If you want to learn the truth—the hard facts—about something, you have to turn to real science, which so far has had little to tell us about the ultimate nature of the mind.” This response conjures up a familiar but impoverished vision of science as a collection of precise mathematical formulae, meticulous experiments, and vast catalogues of species and genera, ingredients and recipes. This is the picture of science as strictly a data-gathering enterprise in which imagination is tightly reined in by incessant demands for proof. Even some scientists have this vision of their profession, and are deeply suspicious of their more playful colleagues, however eminent. Perhaps some symphony orchestra players view their business as nothing but precise noise-making produced under conditions of militaristic discipline. If so, think what they are missing.

In fact, of course, science is an unparalleled playground of the imagination, populated by unlikely characters with wonderful names (messenger RNA, black holes, quarks) and capable of performing the most amazing deeds: sub-atomic whirling dervishes that can be in several places—everywhere and nowhere—at the same time; molecular hoop-snakes biting their own tails; self-copying spiral staircases bearing coded instructions; miniature keys searching for the locks in which they fit, on floating odysseys in a trillion synaptic gulfs. So why not brain-book immortality, dream-writing machines, symbols that understand themselves, and fraternal homunculi without arms, legs, or heads, sometimes blindly following orders like the sorcerer’s broom, sometimes feuding and conniving, sometimes cooperating? After all, some of the most fantastic ideas presented in this book—Wheeler’s solitary electron weaving the universe, for example, or Everett’s many-worlds interpretation of quantum mechanics, or Dawkins’ suggestion that we are survival machines for our genes—have been proposed in complete seriousness by eminent scientists. Should we take such extravagant ideas seriously? We should certainly try, for how else will we ever learn whether these are the conceptual giant steps we need to escape from the most obscure riddles of the self and consciousness? Coming to understand the mind will probably require new ways of thinking that are at least as outrageous—at first—as Copernicus’s shocking suggestion that the Earth goes around the Sun, or Einstein’s bizarre claim that space itself could be curved. Science advances haltingly, bumping against the boundaries of the unthinkable: the things declared impossible because they are currently unimaginable. It is at the speculative frontier of thought experiment and fantasy that these boundaries get adjusted.

Thought experiments can be systematic, and often their implications can be rigorously deduced. Consider Galileo’s crystal-clear reductio ad absurdum of the hypothesis that heavier objects fall faster than lighter objects. He asks us to imagine taking a heavy object, A, and a light object, B, and tying them together with a string or chain before dropping them off a tower. By hypothesis, B falls slower, and hence should act as a drag on A; thus A tied to B should fall slower than A by itself. But A tied to B is itself a new object, C, which is heavier than A, and hence, by hypothesis, C should fall faster than A by itself. A tied to B cannot at the same time fall faster and slower than A by itself (a contradiction or absurdity), so the hypothesis must be false.

On other occasions thought experiments, however systematically developed, are intended merely to illustrate and enliven difficult ideas. And sometimes the boundaries between proof, persuasion, and pedagogy cannot be drawn. In this book there are a variety of thought experiments designed to explore the implications of the hypothesis that materialism is true: the mind or self is not another (non-physical) thing, in miraculous interaction with the brain, but somehow a natural and explainable product of the brain’s organization and operation. “The Story of a Brain” presents a thought experiment that is meant, like Galileo’s, to be a reductio ad absurdum of its main premise—in this case, materialism in the guise of “the neural theory of experience.” “Prelude, Ant Fugue,” “Where Am I?” and “A Conversation with Einstein’s Brain,” on the other hand, are designed to support materialism by helping thinkers over obstacles that have traditionally stood in the way of comprehending it. In particular, these thought experiments are designed to provide a plausible substitute for the otherwise compelling idea of the self as a sort of mysterious, indivisible pearl of mind-stuff. “Minds, Brains, and Programs” is intended to refute one version of materialism (roughly, the version we defend), while leaving some underdescribed and unexplored materialistic alternatives untouched.

In each of these thought experiments there is a narrative problem of scale: how to get the reader’s imagination to glide over a few billion details and see the woods and not just the trees. “The Story of a Brain” is silent about the staggering complexity of the devices to which the imagined brain parts would have to be attached. In “Where Am I?” the virtual impossibility of using radio links to preserve the connectivity in hundreds of thousands of nerves is conveniently ignored, and the even less likely feat of making a computer duplicate of a human brain that could operate synchronously is presented as nothing more than a fancy bit of technology. “Minds, Brains, and Programs” invites us to imagine a person hand simulating a language-processing program which, if it were realistic, would be so huge that no person could perform the steps for a single interchange in less than a lifetime, but we are cajoled into imagining the system engaging in Chinese conversations occurring in a normal time scale. The problem of scale is faced directly in “A Conversation with Einstein’s Brain,” where we are asked to tolerate a book with a hundred billion pages we can flip through fast enough to extract a few conversational gems from the posthumous Prof. Einstein.

Each setting of the dials on our intuition pump yields a slightly different narrative, with different problems receding into the background and different morals drawn. Which version or versions should be trusted is a matter to settle by examining them carefully, to see which features of the narrative are doing the work. If the oversimplifications are the source of the intuitions, rather than just devices for suppressing irrelevant complications, we should mistrust the conclusions we are invited to draw. These are matters of delicate judgment, so it is no wonder that a generalized and quite justified suspicion surrounds such exercises of imagination and speculation.

In the end we must turn to the rigorous methods of hard science—the experiments, deductions, and mathematical analyses—to keep the speculations honest. These methods provide raw materials for suggesting and testing hypotheses, and even serve often as powerful engines of discovery in their own right. Still, the storytelling side of science is not just peripheral, and not just pedagogy, but the very point of it all. Science properly done is one of the humanities, as a fine physics teacher once said. The point of science is to help us understand what we are and how we got here, and for this we need the great stories: the tale of how, once upon a time, there was a Big Bang; the Darwinian epic of the evolution of life on Earth; and now the story we are just beginning to learn how to tell: the amazing adventure of the primate autobiographers who finally taught themselves how to tell the story of the amazing adventure of the primate autobiographers.

D.C.D.

27 Robert Nozick Fiction[51]

I am a fictional character. However, you would be in error to smile smugly, feeling ontologically superior. For you are a fictional character too. All my readers are except one who is, properly, not reader but author.

I am a fictional character; this is not, however, a work of fiction, no more so than any other work you’ve ever read. It is not a modernist work that self-consciously says it’s a work of fiction, nor one even more tricky that denies its fictional status. We all are familiar with such works and know how to deal with them, how to frame them so that nothing the author says—nothing the first person voices even in an afterword or in something headed “author’s note”—can convince us that anyone is speaking seriously, non-fictionally in his own first person.

All the more severe is my own problem of informing you that this very piece you are reading is a work of non-fiction, yet we are fictional characters, nevertheless. Within this world of fiction we inhabit, this writing is non-fictional, although in a wider sense, encased as it is in a work of fiction, it too can only be a fiction.

Think of our world as a novel in which you yourself are a character. Is there any way to tell what our author is like? Perhaps. If this is a work in which the author expresses himself, we can draw inferences about his facets, while noting that each such inference we draw will be written by him. And if he writes that we find a particular inference plausible or valid who are we to argue?

One sacred scripture in the novel we inhabit says that the author our universe created things merely by speaking, by saying “Let there be…” The only thing mere speaking can create, we know, is a story, a play, an epic poem, a fiction. Where we live is created by and in words: a uni-verse.

Recall what is known as the problem of evil: why does a good treat allow evil in the world, evil he knows of and can prevent? However, when an author includes monstrous deeds—pain and suffering—in his work does this cast any special doubt upon his goodness? Is an author callous who puts his characters through hardships? Not if the characters do not suffer them really. But don’t they? Wasn’t Hamlet’s father really killed? (Or was he merely hiding to see how Hamlet would respond?) Lear really was cast adrift—he didn’t just dream this. Macbeth, on the other hand did not see a real dagger. But these characters aren’t real and never were so there was no suffering outside of the world of the work, no real suffering in the author’s own world, and so in his creating, the author was no cruel. (Yet why is it cruel only when he creates suffering in his own world? Would it be perfectly all right for Iago to create misery in our world?)

“What!” you say, “we don’t really undergo suffering? Why it’s as real to us as Oedipus’ is to him.” Precisely as real. “But can’t you prove that you really exist?” If Shakespeare had Hamlet say “I think, therefore I am,” would that prove to us that Hamlet exists? Should it prove that to Hamlet and if so what is such a proof worth? Could not any proof be written into a work of fiction and be presented by one of the characters, perhaps on named “Descartes”? (Such a character should worry less that he’s dreaming, more that he’s dreamed.)

Often, people discover anomalies in the world, facts that just don’t jibe. The deeper dug, the more puzzles found—far-fetched coincidences dangling facts—on these feed conspiracy and assassination buffs. That number of hours spent probing into anything might produce anomalies however, if reality is not as coherent as we thought, if it is not real. Are we simply discovering the limits of the details the author worked out? But who is discovering this? The author who writes our discoveries knows them himself. Perhaps he now is preparing to correct them. Do we live, in galley proofs in the process of being corrected? Are we living in a first draft?

My tendency, I admit, is to want to revolt, to conspire along with the rest of you to overthrow our author or to make our positions more equal, at least, to hide some portion of our lives from him—to gain a little breathing space. Yet these words I write he reads, my secret thoughts and modulations of feeling he knows and records, my Jamesian author.

But does he control it all? Or does our author, through writing, learn about his characters and from them? Is he surprised by what he finds us doing and thinking? When we feel we freely think or act on our own, is this merely a description he has written in for us, or does he find it to be true of us, his characters, and therefore write it? Does our leeway and privacy reside in this, that there are some implications of his work that he hasn’t yet worked out, some things he has not thought of which nevertheless are true in the world he has created, so that there are actions and thoughts of ours that elude his ken? (Must we therefore speak in code?) Or is he only ignorant of what we would do or say in some other circumstances, so that our independence lies only in the subjunctive realm?

Does this way madness lie? Or enlightenment?

Our author, we know, is outside our realm, yet he may not be free of our problems. Does he wonder too whether he is a character in a work of fiction, whether his writing our universe is a play within a play? Does he have me write this work and especially this very paragraph in order to express his own concerns?

It would be nice for us if our author too is a fictional character and this fictional world he made describes (that being no coincidence) the actual world inhabited by his author, the one who created him. We then would be fictional characters who, unbeknownst to our own author although not to his, correspond to real people. (Is that why we are so true to life?)

Must there be a top-floor somewhere, a world that itself is not created in someone else’s fiction? Or can the hierarchy go on infinitely? Are circles excluded, even quite narrow ones where a character of one world creates another fictional world wherein a character creates the first world? Might the circle get narrower, still?

Various theories have described our world as less real than another, even as an illusion. The idea of our having this inferior ontological status takes some getting used to, however. It may help if we approach our situation as literary critics and ask the genre of our universe, whether tragedy, farce, or theater-of-the-absurd? What is the plot line, and which act are we in?

Still, our status may bring some compensations, as, for example, that we live on even after we die, preserved permanently in the work of fiction. Or if not permanently, at least for as long as our book lasts. May we hope to inhabit an enduring masterpiece rather than a quickly remaindered book?

Moreover, though in some sense it might be false, in another wouldn’t it be true for Hamlet to say, “I am Shakespeare”? What do Macbeth, Banquo, Desdemona, and Prospero have in common? The consciousness of the one author, Shakespeare, which underlies and infuses each of them. (So too, there is the brotherhood of man.) Playing on the intricacy both of our ontological status and of the first person reflexive pronoun, each of us too may truly say, “I am the author.”

Suppose I now tell you that the preceding was a work of fiction and the “I” didn’t refer to me, the author, but to a first person character. Or suppose I tell you that it was not a work of fiction but a playful, and so of course serious, philosophical essay by me, Robert Nozick, (Not the Robert Nozick named as author at the beginning of this work—he may be, for all we know, another literary persona—but the one who attended P.S. 165.) How would your response to this whole work differ depending on which I say, supposing you were willing, as you won’t be, simply to accept my statement?

May I decide which to say, fiction or philosophical essay, only now, as I finish writing this, and how will that decision affect the character of what already was set down previously? May I postpone the decision further, perhaps until after you have read this, fixing its status and genre only then?

Perhaps God has not decided yet whether he has created, in this world, a fictional world or a real one. Is the Day of Judgment the day he will decide? Yet what additional thing depends upon which way he decides—what would either decision add to our situation or subtract from it?

And which decision do you hope for?