Sooner or later any theory of consciousness must address this question: How can it be that during sleep, but very occasionally in waking moments too, we have experiences that have nothing to do with the world immediately around our bodies?
The dominant, “internalist” account of consciousness—based on the assumption that consciousness is generated by neural activity in the brain—has no difficulty in responding to this question. Indeed it’s one of the curiosities of internalism that it is most confident when describing those areas of experience about which we are least certain. The internalists say, If I can have the experience of climbing a snowy mountain on a bright day when I am fast asleep in a dark room, this must mean that the brain can generate experience without contact with external reality. Some internalists draw on dreams and hallucinations to suggest that all experience is no more than a form of “reliable hallucination,” a movie in the head with only tenuous relation to the outside world.
By contrast, in our last two conversations, Riccardo Manzotti outlined a radically “externalist” account of consciousness, proposing that our experience is not inside the head at all, but actually identical to the many objects that our bodies and brains carve out from all the atoms, electrons, neutrinos, and photons around us. In short, our consciousness is the world—or the objects—that we experience. There are no manufactured representations of that world or those objects in the head.
Such an approach requires a new notion of what we mean by “an object.” An object is not something that exists absolutely, but in relation to the things around it; in our case, in relation to our bodies and brains. So every experience must have an object, simply because the experience is that object. Mental and physical object are one. If I perceive an apple, there is an apple out there that is my perception.
This idea has its attractions, granting an absolute reality to our experience, in the sense that I am the world I call my experience. It is not a hallucination. It really is there, even if it is as I see it only in relation to my body. But what about dreams?
Tim Parks: Riccardo, surely the fact that we dream is fatal to your theory. Last night, for example, I dreamed I was swimming across a lake in the dark trying to keep my laptop above water with one hand. Who would ever do such a thing?
Riccardo Manzotti: But you like swimming and lakes and your laptop is probably the single most important object in your ordinary life. In general, however strange a dream narrative may be, I would claim that all the objects encountered in it are things we have already encountered, or amalgams of things we have encountered, in our waking experience.
Parks: I’ll have to think about this. Essentially you’re turning the Shakespearian adage on its head: dreams are such stuff as ordinary experience is made on. All the objects of daily life turn up there, albeit rearranged.
Manzotti: For the internalists this ordinariness should be surprising, shouldn’t it? If dreams offer an access to an unconstrained mental world generated within, why is their content so familiar? If color is produced entirely and exclusively in the brain, why don’t we ever dream of new colors?
Parks: I suppose the point is that the brain rehashes what we’ve come across already in the world. The dream is replay.
Manzotti: That’s the standard explanation. The brain learns what colors are by interaction with the world, then plays them back in dreams, a remix of the movie in the head. But if, as neuroscientists maintain, colors are properties manufactured in the brain rather than existing in the world, why would the brain need the world to manufacture them? And why in dreams would the brain be constrained by the colors encountered in daily experience?
Parks: Surely the idea is that each experience we have alters the patterning of electrical and chemical activity in the neurons. When we sleep these “patterns” fire off again, giving us experiences we call dreams.
Manzotti: So, all the qualities of our vastly varied experience remain somehow attached to neural traces? If this is the case, then tasting honey affects certain neurons that are now capable of reproducing a honey flavor in your head any time they want. But not a flavor you’ve never tasted before. Why on earth should that be?
Parks: Riccardo, you’ve elaborated on this fundamental problem of the internalist account in our previous conversations. But this hardly proves your own position. Insisting that we only dream what we’ve already experienced doesn’t get you out of jail at all. The fact is, eyes closed, I dreamed the lake and the laptop when no lake or laptop was there. If, as you claim, every experience is identical with an external object, how can you possibly explain that?
Manzotti: In our last conversation, I warned you that to understand dreams we would have to tackle the question of “the now,” or nowness. You say you dreamed the lake and the laptop “when no lake or laptop were there.” And you say it with great confidence, as if no one could ever get such things wrong. An apple is there when I can reach out and take it. It’s not there when I can’t. Case closed.
But is experience really so cut and dried? For example, from our window on the fourth floor here in Milan we can see the Alps fifty miles away. Are the mountain tops there, the way the apple is there? I can’t touch them from here, can I? Of course, I could set off toward them, but when I get there it will be dark and maybe a snowfall will have utterly changed their appearance. So the mountains are less “there” than the apple.
Parks: But that’s merely a question of distance! It’s banal.
Manzotti: So what about the fly marching across the table beside the apple? It’s right there too, isn’t it? But you can’t grab it the way you can grab the apple.
Parks: Only because I’m not quick enough.
Manzotti: Actually, no. Our hands can easily move quickly enough to grab a fly. The problem is our perception. As Benjamin Libet showed in experiments made in the Seventies and Eighties, in everyday perception there is a time lapse of around 20 to 300 milliseconds between what you perceive and the moment the perception is available for you to act on it. This is customarily explained by saying that our conscious perception is in delay with respect to its external cause, a delay corresponding to the time it takes for the light to travel from the object and then for the signals to pass through the various neuronal synapses. However, there’s another explanation that matches the same data just as well: the things our experience is made of are whenever and wherever they are, even if the neural activity comes later. Our experience is where and when those things are.
Parks: Sorry, I don’t get you. You’re now claiming that not only is experience distant from the body, identical with the object, but, as it were, prior to the body’s reaction to it. Is that it?
Manzotti: Logically, you must agree that if the experience is located at the object and identical with it, it must come before its effects on the body, since, following Einstein, everyone knows that distance is also time.
Parks: This is nonsense. How can my present experience—my now—be in the past? Neuronal activity is now. If there’s a hundred millisecond lapse between the fly and me, that simply means that I see the fly as it was a moment ago, rather than as it is now.
Manzotti: But if the fly you see is different, even by just a few milliseconds, from the fly you’re trying to catch, then we are back with the internalist view that your consciousness is a representation and not, as I am claiming, the object itself, which is always more or less distant from the body in time and space.
But let’s push this conundrum a bit further. Right now, we’re at that time of day, a few hours before sunset, when we can see – with a little craning out of the window – both the moon, which is almost full, and the sun. And they both seem present to you, right?
Parks: They are present. Everything I experience feels now. Otherwise it wouldn’t be experience.
Manzotti: But this sun that feels “now” to you is the sun that shone eight minutes ago. The moon is closer, but it’s still more than a second away from the effect it produces in your body. If this were a starry night, the stars composing the Ursa Major would be scattered between 80 and 128 years away.
Parks: But how does that change things? We all know that even the closest stars are light years away.
Manzotti: Have patience and we’ll get there. Your now, your experience, is made up of all the things causing an effect in your body, your brain, no matter whether from centuries or milliseconds ago, inches or light years away. But you don’t partition your immediate visual experience into past and present; to you everything, sun, stars, apple, fly, is just now. The present, then, dependent on your neural activity, is what caused that neural activity to occur, however near or far. Your now is not a single point on a linear flow of time. It is spread across time and space. There was never a single instant when the stars of a constellation were in the relation to each other that you experience. Because each star is a different time away from your body. As the fly and the mountain are also different times from your body. So it is only relative to your body that the world, which is your composite experience, manifests itself as it is to you.
Parks: Didn’t Einstein start his theory of relativity with a critique of our ordinary ideas of time?
Manzotti: Indeed. Einstein denied that events were “simultaneous” in the sense of being “instantaneous,” as Newton thought. There was no absolute clock ticking away to establish time across the universe. Rather, things interacted together in a mesh of causal processes. All I am doing is applying Einstein’s insight to my understanding of everyday perception.
Parks: I can see there’s a logic in saying that if my experience is located at the objects of perception, and not at my body—spread across space—then it must also be spread across time. I can also see that there’s a link between the internalist notion that our conscious experience is located in a single point in space—between the ears and behind the eyes—and the conviction that we are located in a single point in time. In fact, if consciousness is located in that single point between the ears then logically it must be concocted at that point, since any distance implies a time lapse. The object, which we all know is at least milliseconds away, cannot be identical with the experience in my head. So the experience must be a representation.
Manzotti: Exactly. But let me add that even the internalist approach has difficulty with the idea of time as a point, an instant of nowness. Because the quickest neural processes still require tens of milliseconds to complete as electronic and chemical signals travel back and forth across the meters of neural circuitry packed in our brains. So even for the neuroscientists the physical stuff that they view as constituting our conscious experience is spread over space and time, albeit tiny spaces. In fact, if we wanted to be really rigorous and consider only what is present at one instant in time, the world as we know it would disappear. Sounds, light, voices, gestures, actions, words, all require a flexible notion of nowness that encompasses more than a single instant. Once you accept that, there’s no reason to resist the notion of the “relative now” that I am putting forward.
Parks: Relative in the sense of relative to my body?
Manzotti: Right. For an object to be present simply means that it’s causally present, it’s having an effect on your body, even if it’s not actually in the temporal or spatial vicinity.
Parks: Got it. And I think I’ve got your take on dreams too! When I dream the lake and the laptop, those real objects are having a causal effect on my brain. They are not stored in the brain, they are really affecting it. Hence they are present. The way a distant constellation is present, even if actually each star is a different number of light years away from us and they were never, as you said, “simultaneously” in the physical relation to each other in which I see them.
Manzotti: You’re jumping the gun. There were other things I wanted to say first. But yes, we’re eliminating the naive idea of time as a linear progression of single instants and substituting it with a mesh of causation, just as Einstein did when he explored his theory of relativity.
Parks: But that also means that you’re giving dream experiences the same status as ordinary waking experiences. They are both the result of the same processes of causation.
Manzotti: Absolutely. And that’s how it is, isn’t it? When you dream, it’s real. You are the objects of your experience. You (and remember we’ve said that you are not your body but the experience your body makes possible) were swimming in the lake holding your laptop above the water.
Parks: Desperately anxious that it would fall in. I woke in a sweat.
Manzotti: There you go. Nothing more real than anxiety!
Parks: Very nice. But I’m afraid I don’t buy it at all. And I don’t buy it for this reason: When I see the constellation arranging itself across the light years, there is a direct line of vision between its various parts, the stars, and my body. It makes physical sense, scientific sense that I see it. But in the dream there is no direct line between the lake and my body.
Manzotti: There’s no direct line through space, but there is a causal line. Let’s say you visited a lake a year ago. Your body and brain allowed that stretch of water to start a causal process as a result of which it was part of your visual experience; in short, you saw it. But now let’s suppose the causal process didn’t stop at your visual cortex; it went on to produce a cascade of further effects, beginning a long journey made possible by the unique structure of the brain that allows the causal influence of external events to tick over, as it were, in the background, or as if trapped in a whirlpool, waiting to release its energy when conditions allow.
Parks: I’m sorry but this is beginning to sound rather magical now. And all so convenient for you. I don’t get it at all.
Manzotti: Tim, you’re a kayaker, aren’t you? You paddle your way down wild mountain rivers.
Parks: I do indeed. Some of the best moments in my life.
Manzotti: But you don’t just barrel straight down the river, do you? You take time out here and there. Maybe to wait for others to catch up. How do you do that if the water is moving so fast?
Parks: Easy. Behind each rock, or spur in the bank, there’s an eddy. The water gets trapped there, turning round and round. Shoot into the eddy and you’re out of the stream.
Manzotti: Great. So now imagine the brain with its billions and billions of neurons, its trillions of neural synapses as a huge collection of eddies, each of them the offshoot of a different original external cause. In everyday perception, the powerful current coming from the proximal surrounding environment is so strong that the eddies don’t contribute to the overall flow. Things turn round and round there in a potentially never-ending merry-go-round. Like the Coke can that floats round and round in an eddy. But what happens in a river if the water level falls and the current eases off?
Parks: There’s less tension between eddy and mainstream. The waters mingle. The Coke can escapes.
Manzotti: Right. And when you sleep, the flow of immediate experience eases off and the endless eddies can mingle with the flow.
Parks: Nice analogy, if nothing else… Let me sum up. There’s an original cause, say a Coke can, that, thanks to its effect on my body and brain, becomes an experience. From then on the Coke can will be present whenever that ongoing effect, in the eddies of my brain, is drawn back into the mainstream. At which point my experience will again be the Coke can, however distant in time and space. So my dreams, but I suspect you’re going to say my memories too, are nothing but direct perception of my past.
Manzotti: Careful now! There’s no literal Coke can in your brain, nor do the neurons bear the Coke logo, as it were. We just have a causal wave started by the can, and your experience of course is located at the can.
Parks: In the past.
Manzotti: I’m not sure it’s helpful to say that. Because it implies that you know when your now is, and where. But do you? You experience a star as it was a hundred years ago; so when is your experience? You say your experience is at this moment, one hundred years later, when the light from the star reaches you. But why should your experience be at the same when, the same moment, as the neural activity that doesn’t have anything in common with the star that produced it? Why should experience be located at the point of neural activity when that activity has none of the properties of your experience?
Parks: So, you’re claiming that the belief that our experience is where and when neural activity takes place is a mere prejudice?
Manzotti: Right. The star, the apple, the lake, the laptop, the sun, the moon, the distant Alps, the Coke can, and, yes, our friend the fly now buzzing on the windowpane, these are the things that have the properties of our experience. That is as true when we dream as when we are awake. And however great the time gap between their occurrence and the completion of the neural activity that allows them to be present, in consciousness, our experience is always the object itself, whenever and wherever that object is.
Parks: So, our bodies and brains are at the end point of a causal process, that can be very brief, or interminably drawn out. But we, our experience, are at the origin of the process not the end.
Parks: Even if that origin, as with the stars, occurs before I am born.
Manzotti: Before your body was born.
Parks: But wouldn’t it be so much easier to think of the experience as the whole process, from origin, through the photons across space and time, to the neurons in the head?
Manzotti: We’ve been here before. The process is necessary, but it does not have the properties of the experience. It supports the experience, but it is not it. The only thing that has the properties of the experience is the object itself.
Parks: Enough. I shall now spend a few days dreaming up some serious objections.
This is the seventh in a series of conversations on consciousness between Riccardo Manzotti and Tim Parks.