The Dreaded “Hard Problem”

I’ve been posting thoughts about “qualia,” the qualities of sensory experience. Qualia figure prominently in one of the most baffling enigmas even discussed, and the history of this issue is wonderfully described by Oliver Burkeman. I’ll quote some of his essay, but I urge you to read the whole thing:

“One spring morning in Tucson, Arizona, in 1994, an unknown philosopher named David Chalmers got up to give a talk on consciousness…. the young Australian academic was about to [discuss] a central mystery of human life – perhaps the central mystery of human life – and revealing how embarrassingly far they were from solving it.

“The scholars gathered at the University of Arizona … knew they were doing something edgy: in many quarters, consciousness was still taboo, too weird and new agey to take seriously, and some of the scientists in the audience were risking their reputations by attending. Yet the first two talks that day, before Chalmers’s, hadn’t proved thrilling. ‘Quite honestly, they were totally unintelligible and boring – I had no idea what anyone was talking about,’ recalled Stuart Hameroff, the Arizona professor responsible for the event. … ‘But then the third talk, right before the coffee break – that was Dave.’ With his long, straggly hair and fondness for all-body denim, the 27-year-old Chalmers looked like he’d got lost en route to a Metallica concert. … ‘But then he speaks. And that’s when everyone wakes up.’

“The brain, Chalmers began by pointing out, poses all sorts of problems to keep scientists busy. How do we learn, store memories, or perceive things? How do you know to jerk your hand away from scalding water, or hear your name spoken across the room at a noisy party? But these were all ‘easy problems’, … given enough time and money, experts would figure them out. There was only one truly hard problem of consciousness, … why on earth should all those complicated brain processes feel like anything from the inside? Why aren’t we just brilliant robots, capable of retaining information, of responding to noises and smells and hot saucepans, but dark inside, lacking an inner life? …’

“What jolted Chalmers’s audience from their torpor was how he had framed the question. ‘At the coffee break, … everyone was like: “Oh! The Hard Problem! The Hard Problem! That’s why we’re here!”’

Here’s one way of considering this issue. Suppose in the distant future neuroscience has discovered precisely which brain structures and processes are correlated with specific conscious experiences. They can even read people’s minds: Experimental subject C79 reports that she is recalling a teenage love affair. But a brain scanning machine had already printed out a report, just before C79 spoke: “subject is remembering a high school sweetheart.” Isn’t it clear that we now understand the neural basis of consciousness? Aren’t the neural structures and activities that the scanner detected simply identical to the memory-experience that C79 reported?

Not necessarily. We need to know why this configuration of neural structures and activities constitutes consciousness. “Even if every behavioral and cognitive function related to consciousness were explained,” writes Chalmers, “there would still remain a further mystery: Why is the performance of these functions accompanied by conscious experience? It is this additional question that makes the hard problem hard.”*

Next: the menace of philosophical zombies.

Roger Christan Schriner

*Cited by Uriah Kriegel, Subjective Consciousness: A Self-Representational Theory, p. 271, emphasis added.


Colored numbers, tasteable shapes

I’ve been posting thoughts about qualia, the qualities of sensuous experience. One way to reflect upon qualia is by considering synesthesia, a remarkable syndrome in which a perception that typically occurs through one sensory system (such as hearing) can also be represented in another (such as sight). For instance, some people both hear and “see” sounds. They experience the same auditory inputs with two different types of qualia. “Some synesthetes hear what they see, others see what they hear. One of them felt tastes with his hands. The taste of mint, for instance, felt to his hands as smooth, cool columns of glass. Every taste had its systematically associated feel, and he found this quite useful as an aid to creative cooking.”*

Synthesthetes sometimes see strange colors that they only perceive in association with numbers. How I wish I could see those atypical colors!

Let’s play with the concept of synesthesia by using a thought experiment. Thought experiments are imaginary and often bizarre scenarios that are intended to shed light on philosophical problems. Sometimes these scenarios invoke the concept of God as a metaphorical way of erasing practical difficulties which are irrelevant to the basic idea behind the experiment.

Suppose an all-powerful being altered our bodies so that we started detecting pain as tastes. Instead of feeling a stabbing sensation, a person who stepped on a tack might notice a terribly bitter taste in the bottom of her foot. This taste would represent the damage done by the tack. If something like this is possible, then perhaps when we notice the distinction between tactile and taste sensations, we are noticing something which goes beyond detecting the features of bodily states – something about the mental states that represent these body-states. This would support the internalist claim that we experience states of our own minds rather than just states of the outside world.

To all my readers, may your holiday season be memorable and fulfilling.

Roger Christan Schriner

* Davies, T. N. et al. (2002) “Visual Worlds: Construction or Reconstruction?” Journal of Consciousness Studies, Vol. 9, No. 5-6, p. 75.

Demystifying Sensuous Experience

My previous post considered one of the most mysterious aspects of consciousness, the qualities of sensory experience – sights, sounds, tastes, smells, and physical sensations. It has been incredibly difficult to show how these could be physical states – brain states, for example.

One of the problems is that we understand physical states through science, and science deals with quantities, not qualities. Sensory qualia seem to be another sort of beast entirely. But that may not be as puzzling as it seems. After all, when humans think about their own experiences, it would make perfect sense for them to categorize mental states in qualitative terms when they are actually quantitative. In order to survive, we had to evolve the ability to very quickly tell one thing from another. In the jungle, we needed to distinguish ripe bananas from the green leaves that surrounded them, and from the viper gliding nearby. Thus the visual information profiles of yellow, green, and black must be represented differently in our minds.

Colors, sounds, tastes, scents, and body sensations must also contrast with each other. We would become discombobulated, for example, if tactile sensations suddenly seemed like part of the visual field. So sensory inputs must be clearly “labeled.” So neural activities that constitute sensory phenomena could be clustered into families and sub-families that we automatically think of in qualitative terms. Science, of course, would analyze these same brain states by making quantitative measurements of neural functioning. So the seemingly qualitative nature of sensations and perceptions could be accommodated by science.

Philosophers often say that sensory experiences are like something. So one way of asking what the person sitting next to you is experiencing is to ask what it is like to be that person right now. Presumably there is something it is like to be that individual, but how is that related to what your experiences are like? In particular, are your qualia the same?

I imagine most of us as children wondered about whether some people’s color experiences might be unusual or even reversed. And academicians worry about the possibility of inverted spectra, meaning that your color spectrum might be reversed, relative to mine. Perhaps when you look at a ripe banana the color you see is the same color I call “blue,” and when you look at the sky on a smog-free day you experience what I call “yellow.” It seems intuitively as if this sort of thing is possible. But is it? What do you think?

Roger Christan Schriner


If you’d like to understand what philosophers of mind are vigorously, and sometimes heatedly, discussing, it’s important to understand qualia. Qualia rhymes with Somalia and the singular is quale, pronounced qua-lay or qua-lee. Although it may be an unfamiliar word, it’s a fairly simple idea. Qualia are the qualities of sensory experience. Here’s a list of examples from my book, Your Living Mind: The Mystery of Consciousness and Why It Matters to You (p. 73):

❁ Color experiences – pale pinks, bilious greens, the electric blue of a peacock’s feathers

❁ Auditory phenomena – frog chirps, fingernails on a chalkboard, the rumble of thunder

❁ Smells – garlic, cigar smoke, sizzling fajitas

❁ Tastes – popcorn, overripe bananas, kung pao chicken

❁ Tactile qualia – paper cuts, rib-tickles, foot rubs with warm lotion

❁ Internal sensations – spine-tinglings, mal de mer, the overwhelming rush of an orgasm

Think about your own vivid sensory perceptions – the snap of firecrackers on July 4th, the scent of oranges, the flavor of peppermint ice cream. Each of these perceptions is experienced as a quale, a special quality that is difficult or impossible to describe. How would you explain the smell of rotten eggs, for instance, to someone who has never been able to smell anything? “Well, umm … it’s just … like that. It has a certain quality that I can’t put into words.”

Unfortunately, discussions about qualia are confusing and contentious, and part of the problem is the crazy-quilt complexity of scholarly terminology. “It is hard to find a description of qualia with which two (let alone all) philosophers would agree …”* In any case, it’s hard to explain how sensory qualia such as pains, tastes, and color experiences could exist within a brain.

We describe some aspects of experience quantitatively. I am now visually experiencing two drinking glasses on my desk and three books. The bigger glass seems about 25% larger than the smaller one, and one book looks twice as far away as the other two. But we wouldn’t say red is twice as low as pink or that blue is a little faster than green. We can compare colors in terms of lightness and darkness, but the quality of the color itself is just its own quality, period. Similarly, the sound of a flute has a special quality, and we aren’t sure how to speak of it quantitatively. A musical tone vibrates at a certain number of cycles per second, so we can talk about a sound wave in quantitative terms, but that’s not a sound-experience. To understand what all the fuss is about, we need to understand that qualia are the qualities of our experiences. If experiences are brain events, we need to understand how the qualities that we experience relate to the quantities that science investigates.

Make sense? If not, send me a question or comment and I’ll reply.

Roger Christan Schriner

* Fred Dretske 1995, p. 73.

Where Are Colors?

I’ll now return to my series on mysteries of consciousness, and next on my list is the puzzle of qualia. To put it very briefly, qualia are the qualities of experience, and I’ll begin by talking about a kind of qualia that is especially vivid and interesting, the qualities of our color-experiences.

Although colors are one of the most widely discussed features of consciousness, it’s hard to know where they are actually located. Think of a bright yellow lemon, for example. When scientists examine the brain, they find grayish neurons, and when they examine the fruit itself, they just find a lot of molecules in motion – no color at all. So if we find no colors on the lemon, and no colors in the brain states that occur when we see the lemon, where is the experience that we call “yellow?”

Of course it seems as if colors are on the surfaces of objects, as if every speck of matter sports a paint job, but is that really so? Here are six ways of thinking about this problem:

  1. Colors are surface properties of physical objects. They are not inner experiences.
  2. Colors are inner experiences. Strictly speaking, it is a mistake to say that objects are colored.
  3. “Color” is a word for two different things – features of the surfaces of objects and color-experiences within the mind.
  4. Colors are one thing, located in two places – the surfaces we see and our experiences of those surfaces.
  5. Colors are whatever cause us to be in states that we refer to as colors. You could have a state that you call “seeing purple” on many different occasions, and each time it might be caused by something different.
  6. Colors don’t exist.

I accept option 2, and I’m also comfortable with 3 as long as we remember that surface colors and experienced colors are quite different. But it’s hard to override our common-sense view that “yellow” is both out there and in here, unproblematically one and the same. In any case, one of the deep mysteries of consciousness is the fact that experience seems to have certain qualities that we cannot locate anywhere in the physical world. More about that next time.

Roger Christan Schriner

The Economist Investigates Consciousness

Today I’ll take a break from discussing Six Persistent Enigmas about Consciousness, to comment on The Economist’s recent series on six great mysteries of science. I highly recommend these thoughtful and fact-filled two-page essays, and the final installment (September 12) is titled:

“What is consciousness? The hard problem”

There’s a lot of good material in this piece, but journalism often contains mistakes, even in a respected periodical such as The Economist. A few examples:

“Subjective though it is, consciousness … looks like a specific phenomenon, not a mere side-effect.” But of course side effects can be “specific.”

I think it’s fairly obvious that being conscious, in the sense of having vivid, sensuous, introspectible experiences, is quite different from being self-conscious, in the sense of being aware of oneself. In all probability, many animals that lack self-consciousness are perceptually aware of their surroundings and their own body-sensations. But the article muddles these two uses of the term “consciousness” repeatedly.

Some people with damaged visual cortices have “blindsight.” They report that they cannot see anything in large areas of the visual field, but if they are asked a yes-no question about the “blind” part of their visual field they can often answer correctly – e.g., “Did a light flash just now?” I have never heard of blindsighters spontaneously reaching out and picking up things they cannot see. But The Economist claims they can “point to, and even grasp, objects in their visual fields.” (If researchers have found blindsighters who do that spontaneously, without being cued, I am happy to be corrected, but I’m skeptical.)

These criticisms aside, the whole series is worth seeking out, and it is complimented by a series of brief videos. The video on consciousness showcases major scientists and philosophers such as Christof Koch, David Chalmers, and Daniel Dennett. See

Roger Christan Schriner

What Is It Like to Be a Bat? More on Nagel’s Famous Conundrum

In my previous posting I quoted Thomas Nagel’s famous essay, “What Is It Like to Be a Bat?” Nagel suggested that it is “like something” to be conscious. It is like something, for example, to be a bat. It is like something else to be you, reading these words right now. It is like something to be tasting guacamole. It is like something else to feel nauseous (unless it was really bad guacamole).

And so on. By contrast, most of us assume there is nothing it is like to be a light bulb or a toadstool. They are not conscious, so it is like nothing at all to be them. (Some would argue that the toadstool is sentient, and of course panpsychists would argue that even the light bulb is conscious.)

In time “a consensus … emerged that Thomas Nagel’s expression, ‘what it is like to be’ succeeds in capturing well what is at stake” in discussions about consciousness” (Varela and Shear, Journal of Consciousness Studies, February/March, 1999, p. 3). But even though it was a stunning intuitive breakthrough, some people doubt that it has any clear meaning. David Rosenthal complains that the term “‘what it’s like’ is not reliable common currency” and quotes William Lycan as saying that this phrase is “positively pernicious and harmful” (Rosenthal, Analysis, July, 2011, p. 434).

Here’s an example of the way this phrase can confuse us. Some say that what-it’s-like includes only sensory experiences, such as seeing the blueness of the sky, hearing a harpsichord, or suffering a migraine headache. Others say that non-sensory mental states such as highly abstract thoughts can be “like something.” As Rocco Gennaro writes, “It does indeed seem right to hold that there is something it is like to think that rabbits have tails, believe that ten plus ten equals twenty, or have a desire for some Indian food” (The Consciousness Paradox, p. 27). It’s not easy to adjudicate this dispute.

Another problem is that this term allows us to fuse the subject of experience and the object of experience without realizing we’re doing that. If that sounds confusing, it probably means you’re paying attention. It is very difficult to think and communicate about this issue, but I’ll give it a go:

People sometimes use “what it’s like” to refer to what it is that we are experiencing – blueness, musical notes, pain, and so on. But others use what-it’s-like language to mean what it’s like to subjectively experience these things – what experiences are like for the creature that has those experiences.

This reflects a duality in the way we think about consciousness. Sensory experiences seem to be both what we experience and the way these experiences seem to us. They are a certain way, and they seem a certain way. There is a subtle but crucial difference between the sense that you are experiencing something and the sense that you are experiencing something.

I read Nagel himself as emphasizing the second interpretation. He didn’t talk about what a bat’s echolocation patterns are like. He talked about what it was like to BE the bat, sensing via echolocation. But many philosophers who speak of what-it’s-like emphasize the first interpretation – what the mental states that we are experiencing are “really like.”

I’ll mention just one reason this distinction is important. Theoretically, what we are experiencing and what it’s like for us to experience it could come apart. Suppose pain is a brain state that is sometimes conscious and sometimes unconscious, as when a headache drifts in and out of my awareness. And suppose the experiencing self is a (very complex) brain state that detects and responds to sensory inputs. In principle, my brain could malfunction so that when the experiencing self detects a pain state, it operates as if it was enjoying the experience of tasting peanut butter. In that case, what am I really experiencing, pain or peanut-flavor? (For a spirited argument about this point see the articles by Block, Rosenthal, and Weisberg in Analysis, July, 2011.)

So when people talk about what it’s like to have conscious experiences, this implies both the experience that we’re aware of and what it’s like to be aware of this experience. It fuses the object of experience with the subject of experience. Discussing what-it’s-like makes it sound as if we’re dealing with one idea, but it’s actually an amalgamation of two ideas. This causes confusion.

And speaking of confusion, I’d appreciate feedback about which aspects of this blog-post are unclear to readers. I’m trying to refine my presentation of this murky topic.

In Your Living Mind I wrote: “We seem to have needed such a term, but perhaps we will eventually find better ways to express what Nagel was getting at.” I still find myself using what-it’s-like language, but I try to make clear what this phrase means to me. To me, consciousness involves what experiences are like for the experiencing subject. This seems more in keeping with Nagel’s original intent.

Roger Christan Schriner