Tag Archives: Philosophy of Perception

What We Have In Mind (Consciousness Again)

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Last week, I suggested that consciousness is a type of brain activity, the kind that consists in having a phenomenal field that includes sights, sounds, pains and the internal monologue depicted by authors as the “stream of consciousness”.

I also recommended that we reserve the phrase “conscious of” for the most important things we’re conscious of, things like our everyday surroundings, our feelings and our thoughts, not consciousness itself. This approach would rule out questions like “Are you conscious of consciousness?” that to me seem misguided and misleading. I don’t think we’re conscious of consciousness, but rather conscious of other things.

To say that we’re conscious “of” other things is to say that the components of consciousness represent other things. Thus, some of the brain activity that is consciousness represents things outside our bodies (e.g. trees falling in the forest). Some of it represents things inside our bodies (e.g. heartburn). And some represents things that exist neither inside nor outside our bodies: abstract things like possibilities (e.g. sanity in Washington), fictional characters (Wonder Woman) and ideas (justice or the number twelve).

From an article about dreaming, which is usually considered a kind of consciousness:

One of the main functions of our brain is to constantly create a model of the world around us, a sort of virtual reality that helps us interact with our environment.

When we’re awake, that model is heavily influenced by what we are seeing and hearing and feeling. But during sleep, when there’s not much input from our senses, the brain’s model of the world is more likely to rely on internal information, like memories or expectations.

I’d add that the model is also a model of the world within us and the abstract world of memory, intention and imagination. But thinking of the model our brains create as “a sort of virtual reality” is what I have in mind (that’s a pun). It’s the “sort” of virtual reality that isn’t virtual, however. Patterns of neural activation in the brain (what the model is made of) are quite real. And it’s a model or representation of other things that are quite real too, like falling trees and sprained ankles.

One of the things that makes our conscious model interesting is that it includes events and processes that are strictly or primarily mental, like having a premonition. I don’t know if such things are representations of unconscious mental events and processes. Maybe they aren’t representations at all; maybe they’re patterns of neural activation that don’t refer to or represent anything else. But the evidence suggests that we all have a lot of unconscious brain activity that plays a very large role in what we think and how we feel.

So it would be consistent with the view I’m trying to explain that when you have something like a premonition, what you’re conscious of is a representation of the underlying brain activity (the unconscious premonition processing), as well as any related events in your body (like chills).

To sum up, the position I’ve arrived at seems to be a strange, possibly ridiculous mixture of ideas associated with two great philosophers who are generally seen as opponents: the idealist George Berkeley and the materialist Thomas Hobbes.

Berkeley (1685-1753) argued that nothing exists independently of minds: “To be is to be perceived (or to perceive)”. A person is an immaterial mind or soul. The physical world (the Earth, for example) doesn’t exist independently of our minds. Fortunately, our individual minds are able to get along because God (a kind of super-mind) synchronizes our perceptions. He makes sure that when I perceive a red apple (in my mind), you do too.

Hobbes (1588-1679) argued that nothing exists except physical stuff. We human beings, including our minds, are material things. Even God may be a kind of material being. When I see a red apple, and you see a red apple, therefore, it’s because there’s an apple out there and it’s red. That’s the whole story. 

Where I’ve ended up is to agree with Berkeley that our consciousness has the various elements in it that he called “perceptions” and “ideas”. But I agree with Hobbes that consciousness is a physical phenomenon, a very cool physical phenomenon, but a physical one just the same. And the reason my perceptions usually line up with yours so nicely is because our perceptions represent the same physical world, albeit observed from our individual perspectives. 

Being Conscious, But Not of Consciousness

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A reader (!) asks: Does [what you posted about consciousness yesterday three days ago] mean that we are only conscious of what’s going on in our brains?

That’s an excellent question. When I say that consciousness is certain kinds of brain activity or patterns of neural activation, it may sound like I’m saying that we’re only conscious of brain activity. In other words, we’re not conscious of the rest of the world or the rest of our bodies.

Given what I’m saying about consciousness, I might explain that we are “directly” conscious of our brain activity and “indirectly” conscious of the rest of the world. Or I could say that our consciousness of what’s going on in our heads is “immediate”, while our awareness of everything else is “mediated”, i.e. conveyed through intermediaries, such as the air that carries sound waves to our ears and the nerve impulses that travel from all over our body to our brain.

So when I raised this question yesterday (“Does this mean we are only conscious of what’s going on in our brains?”), I began by saying “in one sense, yes, because that’s where the physical phenomenon of consciousness takes place”. I then said, however, that in the most important sense our brain activity enables us to be aware of what’s happening outside our brains.

Actually, I recommend that we reserve phrases like “conscious of”, “aware of” or “what we experience” for the things we are ordinarily and importantly conscious of. That’s the standard way of speaking and the best way to describe what’s happening when we are conscious. For instance, when you’re awake, are you conscious of your surroundings? When you raise your arm, do you experience any discomfort? Now that you’re on Social Security, are you experiencing any memory loss?

Asking whether we are conscious of what’s going on in our brains amounts to asking whether we are conscious of our consciousness. It’s a misleading question. It’s like asking someone at the North Pole which way is north. To be conscious is to have a certain kind of brain activity. To be conscious of whatever is to be conscious of something other than your brain activity. That’s because there is no way to be conscious of your consciousness. There is no mechanism, no mental apparatus, no meta-consciousness that allows being conscious of consciousness. Consciousness just is. The world you see, that rumbling in your stomach, is what it looks like, feels like, to have the right kind of brain activity. 

You can think about being conscious. We’re doing that right now. But that’s different from being conscious of consciousness. When you think about consciousness, you’re conscious of your thoughts (about consciousness), just like you can be conscious of thoughts about other things. But consciousness itself just is (I could say it is what it is, but that would be redundant and annoying).

Could an evil demon be tricking you, like Descartes wondered? Could you be a brain in a vat, like later philosophers ask themselves? Sure, it’s possible to be seriously wrong about what you’re conscious of. Maybe what you’re conscious of isn’t ever what you think it is. I’m not worried. You shouldn’t be either. 

If a tree falls in the forest, does it make a sound? Yes, it makes the air vibrate and if it creates enough vibrations and there’s anyone around who’s conscious and isn’t deaf, they’ll hear (be conscious of) the crashing sound. 

I’m not sure what I’ve been saying makes sense. I’ve thought about this topic for a long time but never expressed my thoughts this way before. Maybe what I’m saying is way off the track, but it’s all I’ve got right now. Maybe I’ll get back to it again. In the meantime, stay conscious.

In my opinion, that implies being conscious of other things, not consciousness.

What’s So Hard About Consciousness? (With More Words Than Usual)

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Some philosophers call it “the hard problem”. Here’s how Norwegian philosopher Hedda Hassel MĂžrch describes it:

The nature of consciousness seems to be unique among scientific puzzles. Not only do neuroscientists have no fundamental explanation for how it arises from physical states of the brain, we are not even sure whether we ever will….

Our brains do not merely seem to gather and process information. They do not merely undergo biochemical processes. Rather, they create a vivid series of feelings and experiences, such as seeing red, feeling hungry, or being baffled about philosophy. There is something that it’s like to be you, and no one else can ever know that as directly as you do.

Consider the colored objects below. Scientists can describe what happens when a person sees them. They can tell you why the color of a tomato is more like the color of an orange than a lemon. They can point out that if you mix red and yellow light, you’ll get orange. They can use words and numbers to say what’s happening as light is reflected into your eyes and impulses are transmitted along your optic nerves. 

 

But scientists cannot express or capture how any of these colors look when they, or you, or I see them. Words and numbers aren’t up to the task! The best anyone can do is show you examples. See, this is red! 

Consider how the word “red” is defined in dictionaries. Merriam-Webster says “red” means “of the color red”. Not terribly helpful. Consider how Wikipedia introduces its article on “Red”:

Red is the color at the longer-wavelengths end of the spectrum of visible light next to orange, at the opposite end from violet. Red color has a predominant light wavelength of roughly 620–740 nanometers. 

That would be helpful in some circumstances, but the Wikipedia writers added color pictures of strawberries, a cardinal and the Chinese flag to make things perfectly clear. That’s because pointing out examples is the best way, in one sense the only way, to express the meaning of a word like “red”. That, by the way, is called an “ostensive” definition. When language won’t do the trick, show an example. 

The same difficulty applies to the way a violin sounds, the way roses smell and the way tickles tickle. There is something elusive about the way the world appears. There is something incommunicable about experience. Another way of saying this is that the contents of consciousness are a first-person phenomenon. Science as the formal study of the world can describe and explain what’s happening when you hear a violin from a third-person perspective, but the particular sound you hear is beyond words or numbers. There is something about being a person, what it’s like to be a person (or a bat), that has to be experienced firsthand.

Hmm.

Okay, well, that’s interesting. But I’m tempted to say: so what?

That hasn’t been the usual reaction in the history of Western philosophy. Many philosophers have drawn big conclusions from the scientific elusiveness of consciousness. Here, for instance, is Thomas Nagel writing in an exchange of letters a few months ago (he is the author of the famous philosophy paper “What Is It Like to Be a Bat?”):

I do not deny that patterns of neural activation cause experience. What I doubt is that patterns of neural activation alone constitute or are experience—if neural activation is a purely physical process.

The mind-body problem that exercises … me is a problem about what experience is, not how it is caused. The difficulty is that conscious experience has an essentially subjective character—what it is like for its subject, from the inside—that purely physical processes do not share. Physical concepts describe the world as it is in itself, and not for any conscious subject…. But if subjective experience is not an illusion, the real world includes more than can be described in this way.

I agree … that “we need to determine what ‘thing,’ what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose”. But I believe this will require that we attribute to neurons, and perhaps to still more basic physical things and processes, some properties that in the right combination are capable of constituting subjects of experience like ourselves, to whom sunsets and chocolate and violins look and taste and sound as they do. These, if they are ever discovered, will not be physical properties, because physical properties, however sophisticated and complex, characterize only the order of the world extended in space and time, not how things appear from any particular point of view.

Nagel accepts that patterns of neural activation cause consciousness, but he doesn’t think they constitute consciousness. I think he has two reasons for saying this. The first is what we’ve been considering so far: consciousness has properties (“raw feels”) that cannot be captured by science. The second is that neural activation is physical – it occurs in space and time – but, according to Nagel, consciousness doesn’t.

His conclusion is that consciousness is a mental phenomenon that somehow stands apart from the rest of the universe. Our experience is supposedly a special kind of “stuff” that’s somehow separate from the physical world of quantum fields, waves and particles. (How events in space and time can make something happen that isn’t in space or time has always been a problem for positions like Nagel’s. Another philosopher, Daniel Dennett, says it would be a miracle.)

My own view is that patterns of neural activation don’t cause consciousness. Nor are they correlated with consciousness. Instead, certain patterns of neural activity are consciousness. In other words, consciousness is having certain kinds of neural activity.

If consciousness is a certain kind of activity in one’s brain, that kind of activity in one’s brain doesn’t cause consciousness. That’s because a phenomenon cannot cause itself, so saying there is a causal relationship between particular kinds of neural activation and consciousness implies that they are separate phenomena. Nor are such patterns of neural activity correlated with consciousness, because, again, saying that two series of events are correlated implies that they are separate phenomena. But having various patterns of neural activity occurring in your brain can be and is consciousness.

This isn’t to deny that there are correlations of a sort. When a scientist or technician measures or records someone’s brain activity (or even their own), they are collecting data from an outside, third-person perspective, i.e. the perspective of the equipment that does the measuring or recording. Looking at the data that’s gathered, we can say there is a correlation between the data and the subject’s consciousness.

But we shouldn’t go on to say that the patterns of neural activity detected in the brain are correlated with the subject’s conscious experience. That would imply that the neural activity stands apart from the conscious experience, when they’re really the same phenomenon talked about in two different ways or considered from two different perspectives (i.e. the third person “outside” perspective and the first-person “inside” point of view). 

This view is known as the “identity” theory. To me it seems obvious. Consciousness is brain activity. Certain brain activity is consciousness.

Not so fast, however. How can consciousness and having appropriate brain activity be the same? Don’t “they” have different properties? I don’t think so.

Until there is reason to think otherwise, consciousness should be viewed as a physical process that occurs in the brain. Since the brain is in space and time, so is consciousness. When a person is conscious, they are presented with a phenomenal field, a set of representations, including three-dimensional sights (for most of us) and corresponding sounds (for most of us) and smells, tastes and feelings, as well as thoughts (for most of us). Some of these representations have properties like being red or sweet. These properties belong to the components of the phenomenal field. Another way of saying this is that these properties belong to the experience of having certain brain activity.

Of course, if you were to somehow travel around inside a conscious person’s brain, you wouldn’t see any redness or taste any sweetness. Nor would you find any movie screens or loudspeakers. The most you’d observe would be nerve cells, electrical impulses and chemical reactions with their own distinctive properties. You certainly wouldn’t detect the person’s phenomenal field as the person experiences it.

But if enough of those nerve cells, electrical impulses and chemical reactions are functional, a phenomenal field is present. There is consciousness occurring in there with its various properties, by virtue of the fact that having certain patterns of neural activation is enough for consciousness to occur. (As far as we know, it’s also necessary for consciousness to occur.)

Does this mean that we are only conscious of what’s going on in our brains? In one sense, yes, because that’s where the physical phenomenon of consciousness takes place. In another sense, however, and the most important sense, no, not at all. It’s reasonable to believe that consciousness evolved to help us make our way in the world, partly by representing the world to us. Our conscious experience of the world is damned good, in fact phenomenally good, when you think about it.

In fact, it’s so good that we don’t ordinarily have to think about it at all. We just use it to get around, rather like we use maps, photographs, recordings and other representations. Someone shows you a picture of Miami and asks if you’ve ever been there. Do you say “Yes” or “No” or “What do you mean? Have I ever been in that photograph in your hand?” If you’re not being a smart ass, you’ll answer “Yes” or “No”, because that’s how representations work.

In similar fashion, if someone asks you if you want the banana lying on the table, do you say “Yes” or “No” or “What do you mean? Do I want the portion of my visual field that is mostly yellow with a little bit of brown and green?” Saying “Yes” or “No” is the natural way to respond. It’s true that you can’t keep your consciousness in your glove compartment or put it on Facebook. Plus, your consciousness is what makes it possible to use those other kinds of representations. Consciousness doesn’t represent the world in the same way that maps and photographs do. But in addition to helping us think about the world, remember the past and imagine the future, consciousness also helps us observe and navigate the world, like less simple representations do. 

So that’s what I think about consciousness. Understanding how or why consciousness happens in human and animal brains is a major challenge for scientists who study brains, but it isn’t “the hard problem” most philosophers make it out to be.o-142765670-facebook

The Data From All the Senses, Part 2 (Lengthy)

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When I refer to “sense data”, I mean information that’s conveyed in one of several ways, either through one of our many senses (of which there are more than the five Aristotle counted), or by whatever other means information makes its way into our stream of consciousness (for example, the introspection that allows us to carry on inner soliloquies). Philosophers sometimes use the term “qualia” to refer to “the introspectively accessible, phenomenal aspects of our mental lives”, but “sense data” emphasizes the informational aspect of our experience. I also think it’s appropriate to think of our conscious experience as a whole. The term “data”, understood as a collective noun, emphasizes what’s often called “the unity of consciousness”.

A term that could be used is in place of “sense data” is “sensorium”. Wikipedia cites the Oxford English Dictionary:

A sensorium is the sum of an organism’s perception … where it experiences and interprets the environments within which it lives…. In medical, psychological, and physiological discourse it has come to refer to the total character of the unique and changing sensory environments perceived by individuals. These include the sensation, perception, and interpretation of information about the world around us by using faculties of the mind such as senses, phenomenal and psychological perception, cognition and intelligence.

As David Chalmers put it in the article I quoted a few days ago: “What unites all of these states is that there is something it is like to be in them. All of them are states of experience.”

So what is sense data? From what is ordinarily called the “mental” point of view, sense data is information expressed as sights, sounds, smells, feelings, thoughts and so on. Although a computer can run a program perfectly well with one source of information (the data stored as tiny magnetic regions on a hard drive, for example), creatures like us need more. We require lots of information about the world in order to survive and it’s beneficial to collect that information in more than one way (echolocation would be especially handy at night). 

Hence, we evolved with various capacities for collecting information about the world inside and outside our bodies. If the information we collect is accurate, it will generally allows us to maneuver successfully and avoid difficulties. If it’s garbled, incomplete, hard to understand, illusory or even hallucinatory, it will tend to be less helpful.

From what is ordinarily called the “physical” perspective, however, sense data is activity in our brains. Scientists, of course, can only detect what’s happening in our brains up to a point, since the technology is so new. We, however, have a front row seat, metaphorically speaking. In fact, we each have a metaphorical theater to ourselves. We each experience some of the activity in our brains as sense data, i.e. sights, sounds, smells, feelings, thoughts and otherwise. Nobody understands how this works yet – how or why particular kinds of activity are experienced in particular ways – but that seems to be only a matter of time.

Among professional philosophers, the idea that sense data or conscious experience is brain activity is controversial, although not so much among scientists who study the brain. The so-called “identity theory” has been debated for decades and various alternatives have been offered. Nevertheless, it still seems to me that mental activity is brain activity, somewhat like heat is the motion of atoms or molecules, a cloud is water vapor and a squirrel is a collection of cells. 

One big objection to the identity theory that seems very wrong is that it leaves no room for minds or mental activity. Many philosophers used to believe that the mind is a mental substance that’s somehow attached to the physical substance of the body (and that made sense if a person’s mind or soul was supposed to float away post mortem). Very few philosophers think that today. Yet there are still those who believe that mental properties are very different from physical properties. Property dualism, in particular, is the idea that consciousness is a fundamental property not reducible to physical properties.

I don’t see any good reason to believe that. The simple, most plausible explanation for why so-called mental events or properties seem different from so-called physical events or properties is this: when we’re conscious, we experience some physical events in our brains as mental events (what I’m calling “sense data”), but we never experience other physical events, either in our bodies or outside them, in the same way. The traditional way of describing this distinction is to say that we have direct experience of what’s happening in our conscious minds and indirect experience (via our eyes and ears, for example) of everything else. 

Consider what we know about perception and feelings like pain or hunger. Stimuli of various kinds come in contact with specialized cells in the body. Electrical impulses make their way via the nervous system to the brain. A tiny number of these impulses are combined with the brain’s own contributions, resulting in conscious experience. It’s the activity in the brain itself that ultimately counts.

You really could be a brain in a vat and have a vivid mental life, assuming the technology existed to allow your brain to receive the necessary stimuli (and thus the necessary information to process) and to react accordingly (by seeking new stimuli, for example, as in “Hey, what’s that noise over there?”). Using the traditional terminology, It’s the end product (the sense data) that you are “directly” aware of. So long as that information kept arriving and your brain could react appropriately, your world would seem the same.

It’s the things that information is about, whether it’s the sunburn on your back, a band playing in the park or your daughter’s first day at school, that we are “indirectly” aware of (again using the standard terminology). But all of it is (or was or will be) physical stuff, whether it’s the band in the park, the electrical stimuli or the brain’s own activity. It’s all ultimately composed of things like quarks and bosons (and maybe some dark matter or dark energy, whatever those are).

But the direct vs. indirect distinction can be misleading in at least two ways. First, calling our awareness of things outside our brains “indirect” suggests that there could be a more direct way of being aware of such things. But how could that possibly be? How could I possibly be more aware of the chair I’m sitting in than by sitting in it, looking at it, measuring it, touching it and so on? Experiencing something outside of us isn’t and cannot be the same as experiencing the brain activity that’s part of us. Nevertheless, using our senses to gain knowledge about such things is the ideal, most direct way there could possibly be.

Second, saying that we are directly aware of sense data may suggest that our awareness is complete. It’s sometimes said that we have “privileged access” to our sense data. That’s certainly true, since nobody else has the same access to our sense data that we do. Similarly, the Stanford Encyclopedia article on sense data lists this as the third defining feature of traditional sense data theories: “Sense data [has] the properties that perceptually appear to us”. That’s usually understood to mean that we can’t be mistaken about what our sense data is. We may interpret our sense data incorrectly, but if you have blue sense data, your sense data is definitely blue, even if the thing your sense data is about (the wall in front of you, for example) isn’t blue at all. It could be a different color, as we usually describe such things. In reality, it’s got no “color” (the blueness you actually see) in itself at all. 

This doesn’t mean that we can always accurately describe what our sense data is or even know what we’re sensing. Data, after all, is sometimes vague, incomplete, too complex to understand and even inconsistent. (Imagine seeing an object directly in front of you that isn’t there when you try to touch it.) It’s reasonable to say that sense data always has the properties that perceptually appear to us, so long as we don’t take that to mean we are always clear about what those properties are.

The most popular objection to sense data theories is that they break the link between us and the external world. If we’re only aware of sense data, how do we know that anything outside our own minds even exists? How do we know that there is a physical world at all? Or perhaps you and I are like Keanu Reeves before he was unplugged.

Given the sense data I’ve had over the years and am still having, I’m very sure that there is a physical world outside my mind that contains New York City, our cat, Rice Krispies and aluminum siding. But am I absolutely, completely, 100% certain beyond any doubt whatsoever? Not really. I could get an extremely, extremely big surprise one day.

But so what? I’m not absolutely, completely, 100% certain that the world wasn’t created 10 seconds ago, with geological strata and historical records in place and all of us enjoying false memories of years gone by. Being able to conceive of a very different world doesn’t make that very different world plausible. Philosophers (some of them) are paid to worry about these things, and many have tried to prove beyond any possible doubt things we and they already know to be true. But the quest for absolute certainty on this or almost any other topic is a waste of time. It’s impossible to achieve and wouldn’t be of any use if it was.

In conclusion, I should mention that, in a 2009 survey of philosophy professors, graduate students and others who follow academic philosophy, only 19% of the respondents accepted or leaned toward “sense-datum theory” or “qualia theory” in the philosophy of perception. However, applying simple labels to philosophical theories is extraordinarily difficult. The most popular answer was “other” with 43%, but coming in second was “representationalism” with 26%. Another article in the Stanford Encyclopedia describes representationalism or representative realism as follows:

… our immediately experienced sense-data, together with the further beliefs that we arrive at on the basis of them, constitute a representation or depiction of an independent realm of material objects — one that we are, according to the representationalist, justified in believing to be true.

I couldn’t (and didn’t) say it better myself.

PS — It’s very difficult to contract Ebola in a country with a decent public health system, so please don’t worry. It’s not spread like a cold or the flu. If you’re in a country with a poor public health system and people are getting the disease, please don’t expose yourself to the bodily fluids of someone who has a high fever, body aches, etc. You can only get it from the bodily fluids of someone who already has symptoms.

The Data From All the Senses

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Alan Lightman, currently Professor of the Practice of the Humanities (!) at MIT, has posted a short article about consciousness at the New Yorker‘s site. Its centerpiece is a visit with Robert Desimone, an MIT neuroscientist who is trying to understand what happens in the brain when we pay attention to something.

Neuroscientists already know that different parts of the brain are activated when we look at faces as opposed to other objects. In one of Desimone’s experiments, people were shown a series of photographs of faces and houses and told to pay attention to either the faces or houses, but not both.

When the subjects were told to concentrate on the faces and to disregard the houses, the neurons in the face location fired in synchrony, like a group of people singing in unison, while the neurons in the house location fired like a group of people singing out of synch, each beginning at a random point in the score. When the subjects concentrated instead on houses, the reverse happened. Furthermore, another part of the brain, called the inferior frontal junction, a marble-size region in the frontal lobe, seemed to conduct the chorus of the synchronized neurons, firing slightly ahead of them.

 Evidently, what we perceive as “paying attention” to something originates, at the cellular level, in the synchronized firing of a group of neurons, whose rhythmic electrical activity rises above the background chatter of the vast neuronal crowd. Or, as Desimone once put it, “This synchronized chanting allows the relevant information to be ‘heard’ more efficiently by other brain regions.”

Something else that’s interesting in the article is what the neuroscientist says about what’s been called philosophy’s “hard problem”, i.e. understanding the nature of consciousness: 

Without hesitation, Desimone replied that the mystery of consciousness was overrated. “As we learn more about the detailed mechanisms in the brain, the question of ‘What is consciousness?’ will fade away into irrelevancy and abstraction,” he said. As Desimone sees it, consciousness is just a vague word for the mental experience of attending, which we are slowly dissecting in terms of the electrical and chemical activity of individual neurons.

DeSimone compares understanding consciousness to understanding “the nature of motion” as it applies to a car. Once we understand how a car operates, there’s nothing more to say about its motion. Or in a physiological comparison he might have made, we will eventually understand what consciousness is or how it works just like we now understand what digestion is or how it works.

But I think there’s something importantly different about consciousness as compared to the motion of a car or even the digestion of a sandwich.This is how David Chalmers, the philosopher who first referred to the “hard” problem (as opposed to the “easy” problems) of consciousness, put it in his 1995 article “Facing Up to the Problem of Consciousness”:

Consciousness poses the most baffling problems in the science of the mind. There is nothing that we know more intimately than conscious experience, but there is nothing that is harder to explain. All sorts of mental phenomena have yielded to scientific investigation in recent years, but consciousness has stubbornly resisted….

The really hard problem of consciousness is the problem of experience. When we think and perceive, there is a whir of information-processing, but there is also a subjective aspect…. This subjective aspect is experience. When we see, for example, we experience visual sensations: the felt quality of redness, the experience of dark and light, the quality of depth in a visual field. Other experiences go along with perception in different modalities: the sound of a clarinet, the smell of mothballs. Then there are bodily sensations, from pains to orgasms; mental images that are conjured up internally; the felt quality of emotion, and the experience of a stream of conscious thought. What unites all of these states is that there is something it is like to be in them. All of them are states of experience.

It is undeniable that some organisms are subjects of experience. But the question of how it is that these systems are subjects of experience is perplexing. Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? 

So Desimone claims that once we understand the physical processes that occur in the brain (the mechanisms of consciousness), the philosophical problem of consciousness will evaporate. Chalmers, on the other hand, says that even if we were to understand the “physical processing” in the brain, the hard problem of consciousness would remain. According to Chalmers, “specifying a mechanism that performs the function” of consciousness, as Desimone hopes to do one day, won’t solve the mystery at all.

I agree with Desimone up to a point. I think the neuroscientists will eventually answer the philosophers’ question as Chalmers posed it in the paragraphs above. Why should such and such physical processing give rise to an inner life? Well, why should such and such physical processing give rise to digestion or respiration or, for that matter, to water boiling or leaves falling? When such and such physical, chemical or biological events take place, what happens is digestion, respiration, water boiling and leaves falling, as the case may be. If an organism’s parts are arranged a certain way, the organism will have an inner life. Or if, as might be the case one day, a machine’s parts are arranged a certain way, the machine will have an inner life. That’s how the world – the world we happen to be in – works (or will work).

I don’t believe this “why should” question concerning experience or consciousness is very interesting from a philosophical perspective. It seems to me that it’s “merely” a very difficult scientific question to which scientists haven’t yet found the answer. It certainly isn’t the hardest problem in philosophy.

To me, a more interesting question is this: What is felt experience anyway? What exactly is the deep blue or middle C that we experience? For example, when we look at an orange, the precise nature of our experience depends on several factors, including the surface of the orange, the light in our environment and our sensory apparatus. That’s why it makes no sense to say that the surface of an orange is orange in itself. When we hold an orange, the surface feels bumpy, but it presumably wouldn’t feel the same way if we were much, much smaller or much, much larger.

I’m not suggesting at all that David Chalmers has failed to recognize the real issue here. But I think that stating the issue in this way emphasizes the most puzzling aspect of consciousness. Here’s another way of putting it: if the world outside of us isn’t just as we experience it, and it’s not in our heads either (there are relatively few colors or sounds inside our brains), where the hell is it? 

These days, philosophers often compare brains to computers. The brain is the hardware and the mind is the software. But it occurred to me recently that software doesn’t do anything unless it has data to process (that’s not a great insight if you’ve ever worked with or thought about computers). This got me to wondering if we should think of our experience as data. Not the kind of data that computers process, but a special kind of data that takes a variety of forms (in Chalmers’ words, “the felt quality of redness, the experience of dark and light, the quality of depth in a visual field….the sound of a clarinet, the smell of mothballs…. bodily sensations…. mental images…. the felt quality of emotion…. a stream of conscious thought”). We might call this kind of data “sense data”. 

But, lo and behold, that’s exactly what a number of philosophers in the early 20th century, including Bertrand Russell and G. E. Moore, began calling it. (Actually, I already knew that, but it was still a pleasant surprise when I realized I’d gone from thinking about computers to thinking about a 100-year old theory).

Theories that refer to sense data and similar entities aren’t as popular among philosophers as they used to be, but such theories have been one of the most discussed topics in epistemology (the theory of knowledge) and the philosophy of perception for a long time. William James referred to “the data from all the senses” before Russell and Moore (although James wouldn’t have accepted Russell’s or Moore’s particular views). And sense data theories had their precursors in the 17th and 18th century writings of Rene Descartes and the British empiricists Locke, Berkeley and Hume. 

As usual, the Stanford Encyclopedia of Philosophy has a helpful article on the subject. The author, Michael Huemer, characterizes sense data in this way (using “data” in the traditional plural sense rather than as a singular collective noun):

On the most common conception, sense data (singular: “sense datum”) have three defining characteristics:

  1. Sense data are the kind of thing we are directly aware of in perception,
  2. Sense data are dependent on the mind, and
  3. Sense data have the properties that perceptually appear to us.

Many philosophers deny that sense data exists or that we’re directly aware of it. Proposition 3 above is also especially controversial. It’s also often argued that if we were actually aware of sense data, we’d be cut off from the world around us. I don’t plan to discuss any of this further right now, but it’s a topic I want to get back to. It’s a really hard philosophical problem.

PS — There is a funny site called Philosopher Shaming that features anonymous and not so anonymous pictures of philosophically-inclined people owning up to their deepest and darkest philosophical secrets. I uploaded my picture two years ago: 

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