The Pizza Thought Experiment

“I think therefore I am.” Descartes declared thinking the ultimate reality, the only way to be sure of one’s existence. He located that thinking in the mind and believed it was immaterial, made of spirit, communicating with the physical body through the pineal gland at the top of the spine. Times have changed, and scientists now look for explanations of the experience of thinking in the billions of neurons in the brain with their trillions of electrical connections and chemical processes. Yet the location of thought remains firmly in the head. Challenging this, Riccardo Manzotti has suggested that our experience actually lies outside our bodies, one with the objects of our perception. He has extended this to dreams and hallucinations, treating them as cases of delayed and muddled perception. But surely thinking and, in particular, the internal monologue that most of us live with and call the self can’t be imagined as taking place anywhere but in the narrow confines of the skull…

—Tim Parks

Tim Parks: When one thinks of the richness of conscious life, that constant overlapping of thought and perception, the words that go back and forth in our minds, as we walk down the street, or close our eyes to sleep, it is very hard to see how it could be conceived as having a reality outside our bodies.

Riccardo Manzotti: We need to establish what we mean by a thought. Have you ever seen a thought, for example? Has any scientific instrument ever identified one? Can you build a thought detector? More particularly, do you really experience a thought, any thought, as separate and different from the object of that thought?

Parks: You obviously want me to answer no to all those questions. But I’m not sure about the last. I do have the impression that I experience thoughts and that what I experience is not identical with the thing I am thinking about…

Manzotti: In that case, the thought is very likely to be identical with the language in which it is framed. Basically, we have two options: either we think things directly, or we think words and sentences about things. I suggest we put language on hold for a moment and concentrate on thinking things and situations directly. When I think of, say, the Coliseum, what is my thought of the Coliseum if not the Coliseum itself?

Parks: You are going to try to include thoughts in the category of prolonged, deferred, or reshuffled perception, as you did with dreams and hallucinations. Some previous contact with the Coliseum, or with a photo or film of the Coliseum, or with something written about the Coliseum, continues to act on my body and I think the Coliseum.

Manzotti: Right. There is no such a thing as a thought that lies between your body and the Coliseum, or the photo you saw of it, or the article you read about it, no need for some sort of immaterial thinking magic to connect your actions with the external world. Simply, there is your body and there is the external thing your body has been in contact with. Of course, there’s also a lot of neural machinery that allows the world to produce effects through the body, but the experiences we call thoughts are no more, no less, than the external object as it affects the body.

Parks: It seems to me that you are constantly seeking to reduce what most people call mental life to a direct experience of the material world, yet, in order to do so, you yourself come out with complex and provocative formulations that can’t easily be brought back to any original contact with the world.

Manzotti: Let’s try an experiment. Think of something, right now. Anything.

Parks: Okay.

Manzotti: Now describe the thought you’ve come up with.

Parks: Eggplant and parmesan pizza.

Manzotti: That’s not a thought. That’s what you thought about! I didn’t ask you to describe the object of your thought. I told you to think of something, then describe the thought, not the something.

Parks: Hmm. Pleasing. Mouth-watering. Steamy.

Manzotti: These are all adjectives that apply to the pizza or to the body’s reactions to the pizza. What you like to think of as the thought is simply the object.

Parks: But when I move away from an object, my thinking allows me to accomplish all kinds of things I couldn’t do without thinking—not least, engaging in this conversation.

Manzotti: Do you think when you play chess?

Parks: I hope so. Though I’m a poor player.

Manzotti: You think things like, “If I move my knight to capture his bishop, I risk exposing my king to a queenside attack from the rook presently lurking behind a pawn shield”?

Parks: Stuff like that.

Manzotti: And you call that thinking?

Parks: What else could you call it?

Manzotti: Over the last fifty years computers have been developed that play chess far better than you do, not to mention solving mathematical problems, driving cars, and so on—achievements you associate with thinking. But do computers have thoughts? Of course not. Has anyone ever detected a thought inside a computer? No. There are no courses or exams about thoughts when you take a degree in IT or AI. What we call thinking is a form of action, a way our body organizes our behavior in response to those external causes that our so-called thoughts are about.

Parks: But the computer plays without any experience of playing. It doesn’t say to itself, “Huh, now he’s got me in a corner.” It doesn’t rejoice when it wins, or curse when it loses. It doesn’t even know it’s playing chess. It just acts out a series of instructions.

Manzotti: I didn’t say that computers were conscious. However, computers show that cognitive skills do not require thoughts. You do not need immaterial thoughts to choose in a chess game which move is best. It is a physical chain of causes and effects that starts with external objects and ends with actions.

Parks: It seems now you’re distinguishing between a thought, which you say is simply at one with whatever object the thought is supposedly about, and then this activity—most people might call it “mental activity”—that allows us to hop from one thought (one object, as you see it) to the next, connecting them together. I need some clarity here.

Manzotti: The notion of “thoughts” has much the same function as the notion of “luminiferous ether” in the nineteenth century. Scientists couldn’t understand how light could travel, so they invented this mysterious medium that somehow propagated light. But just as light does not need ether to travel, so objects do not need thoughts to have causal effects on our bodies. When I say, “I think of x,” it is simply a manner of speaking to explain that x is exerting effects through my body.

Parks: But thoughts are different from one’s immediate perceptions of the world. When I think of, say, my daughter, it is quite different from actually seeing her, or even dreaming of her.

Manzotti: Absolutely. When you think of her, the object that is identical with your experience is different from the object you see when she is physically present. Just as reaching a hand to touch something inside a drawer and then looking in the drawer leads to different objects of perception—the object, remember, being relative to the perceptive faculties, not absolute. So you could think of thought as another form of perception that allows a different object to affect your body. The way touch, sight, and hearing allow different objects to affect us.

Parks: As I recall, Buddhists believe we have six senses, the mind being the sixth, and thoughts being the things the mind perceives.

Manzotti: I’m afraid I know very little of Buddhist ideas, but yes, you could say we’re talking about another group of objects of perception. For instance, when I see an apple, it’s easy to pinpoint the external object that is affecting my body, just as when I hear or touch something. But what about those situations where what is acting on me, my experience, is a combination of various objects, separate in space and even time?

Parks: For example?

Manzotti: A constellation of stars is perceived as a single shape, despite the distances between the separate objects and the fact that they are only in that apparent spatial relation thanks to the different times traveled to reach us. Each star, though, is there in time and space. More mundanely, objects behind and reflected in a shop window act together to make a whole object of perception. Or again, a melody spread across time is combined into a unity.

So why should we put a limit to this process? What if the causes of one’s actions, one’s behavior, were an extended collection of external causes, deriving from external objects, or even the relations between them? Such is the case when I react not because there are two specific things, but because the relation between those things acts itself as a new object. You’re on a long walk, you’re only wearing a T-shirt, a raincloud appears in the sky. The relationship between these things presents itself as a new object: fear of getting cold and wet. Of course, it’s not easy to ascribe physical properties to a relation like this, but with the right physical system, that relation can nevertheless exert an effect.

Parks: The right physical system being?

Manzotti: The human body with its extraordinary brain. Beyond the so-called early sensory cortexes, there are many cortical areas whose functions remain obscure. Very likely, they are allowing the external world to come together in novel ways that correspond to complex external objects. You could think of the brain as a huge eye that, by reorganizing its neural structure, is able to perceive all kinds of complex objects across space and time.

Parks: And you’re saying all this connecting up is what we call thinking.

Manzotti: If hard pressed, I’d say the external objects were the thoughts, and their churning over the thinking. But I’d prefer not to use these words because I’m trying to describe what happens without bringing in fictive mental entities. Let’s just say that the human cortex with its billions of neurons has trillions of “gates,” each of which is causally continuous with the external world. These gates keep reorganizing their pathways so that the objects that affect our body and behavior become those that best match our needs.

Learning is a process of adding and connecting such objects – objects that are really out there, not in the mind. The internal activity of the brain allows the objects that are us—and we are not our brains, remember, we are our experience—to be more complex than those singled out by the immediate senses. The body intercepts separate notes struck on a piano, the brain allows the sonata to affect us as a single object, which it is, relative to our brain. In general, objects that would otherwise be separate—something visual, something tactile, something auditory—become a whole and affect the body as a single object, a crunchy candy bar, for example. Because, relative to our body, they are a single object.

Parks: And presumably, this constant mixing and remixing of the world has a goal.

Manzotti: Of course. To behave in a more successful or appropriate way. This is entirely in line with an evolutionary view of the brain.

Parks: So what we call thinking is a practical activity, a churning of causal paths, a reshuffling of the world, the making of causal connections between the world and our actions. While direct perception—seeing, hearing, touching—is unavoidable. It simply is our experience.

Manzotti: In the past, philosophers usually assumed thinking to be a superior cognitive skill capable of penetrating the essence of reality. So thinking was associated with truth, while individual experience was dubbed subjective and downgraded to mere appearance. In fact, the opposite is the case. It is our direct individual experience that is unerringly true; being one with the external world, it cannot be wrong.

What we call thinking, on the other hand, is the way in which the world and our behavior are combined and, as such, it can all too easily be wrong. For example, I may think that a mushroom I’ve picked in the woods is edible, but when I eat it, I’m poisoned and die. This wasn’t a mistake in my visual or tactile experience of the mushroom, which simply was what it had to be, but rather in the pairing between what I saw and what I did.

Parks: I can’t help feeling that we’re now talking about thinking as going on in the head. As if there were the experience of the mushroom outside and the thinking inside.

Manzotti: Of course, there is always a great deal going on in the brain, but thoughts remain external objects, experiences, which exist in relation to our body, of which the brain is a part. Thoughts are just more complex objects created by combining a number of objects together. In this case, we have the mushroom, which is a rather simple, proximate object, the appetite of the body, which is a property of the body, itself an object, past occurrences of eating mushrooms, again events obviously involving objects and capable of still acting on the body. These come together in a single object that we dub a desire to eat the said, alas poisonous, mushroom.

Parks: What about creative thinking?

Manzotti: Most of what happens in our brain, the connections it’s constantly bringing about, is unconscious. So creative people do most of their thinking while they do other stuff, or even while they sleep. There is abundant anecdotal evidence of the brain reaching solutions without our being aware of it. “A thought comes when ‘it’ wants to,” says Nietzsche, and not when “I” wish. So thinking is a process of physical reconfiguration of causal paths, a complex form of perception. To use the word “mental” in opposition to physical, in order to give some special status to this process, only confuses matters.

Parks: So there’s no great merit in being creative.

Manzotti: Creativity is highly prized because it allows all kinds of novelty to occur, but it doesn’t necessarily require either conscious experience or even a mind. After all, natural selection has created millions of incredibly complex structures. Yet there is no universal mind at work, just an endless permutation of DNA bases singled out through practical operations. Thinking is the same.

Parks: Very often, though, we are indeed aware of thinking, aware of a voice chattering in our head. Particularly when I write, I’m aware of moments of breakthrough, moments when I’ve arrived at some new synthesis, perhaps. It is all very conscious. Sometimes, painfully so. How does this fit in?

Manzotti: “Voice,” you say. We’re back to language. It’s obvious that there are thoughts that can only come in words. The formulation “thoughts are imaginary entities,” for example, is an entirely verbal construct. It even includes the notion of something that, by definition, cannot be an object in the world: an imaginary entity.

Parks: So? How can this thought be the result of an object in the world? Unless you want to say that language or words are the object. But in that case, where are these words? Since you love to say that everything is physical and hence everything is located somewhere, you will have to tell us where these words are. And where, indeed, if not in my head?

Manzotti: Ha. I will tell you all that, and more, but in our next and penultimate conversation. Language is too big a subject to tack on in a last paragraph. Let me leave you, though, with a quote from E.M. Forster to mull over: “How can I tell what I think till I see what I say?” If we understand what he meant by that, I believe we have the beginnings of an answer to your question.

Tim Parks is Associate Professor of Literature and Translation at IULM University in Milan. He is the author of many novels, translations, and works of nonfiction, the latest being Life and Work: Writers, Readers, and the Conversations Between Them and the novel In Extremis. (June 2017). Riccardo Manzotti has a PhD in Robotics and degrees in The Philosophy of Mind and Computer Science. He teaches Psychology of Perception at IULM University, Milan (Italy), and has been a Fulbright Visiting Scholar at MIT. He has specialized in AI, artificial vision, perception and, most of all, the issue of consciousness. After working in the field of artificial vision, he focused his research on the nature of phenomenal experience, how it emerges from physical processes and how it is related to objected perceived.

This is the thirteenth in a series by Riccardo Manzotti and Tim Parks on consciousness. See the first, the second, the third, the fourth the fifth, the sixth, the seventh, the eighth, the ninth, the tenth, the eleventh and the twelfth.

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