The Philosophical Zombie

Can old bedraggled zombies reflect logically on their condition and calmly resign themselves to their fate? Perhaps, but that’s not what this post is about. In the study of consciousness, philosophical zombies were first described in a famous thought experiment by Australian philosopher David Chalmers. His discussion helps underscore the mysterious nature of qualia (the qualities of sensory experiences).

Chalmers proposed the zombie idea to highlight the Hard Problem of consciousness, the problem of understanding how conscious experiences result from (or are identical to) brain activities. A philosophical zombie is a hypothetical creature whose brain has precisely the same physical structures as ours and operates in the same ways that our brains do, but without consciousness.

Here’s an important point that is often overlooked: This creature would be conscious in the ways that psychology understands the structures, abilities, and functions of consciousness. “He will be awake, able to report the contents of his internal states, able to focus attention in various places, and so on.”* Furthermore a psychologist studying you and your zombie twin would discern no difference in behavior. But even though it would be conscious in a certain sense, it would lack conscious experiences. It would be utterly devoid of qualia, and it would never be in any state that is “like something.”

Thus, as Philip Goff notes, when it screams it is not in pain. “Its smiles are not accompanied by a feeling of pleasure. Its negotiation of its environment does not involve a visual/auditory experience of that environment.”**

Although zombies would have thoughts, these thoughts would not involve conscious perceptions or sensations. A zombie that is screaming might think, “I’m in pain!” but it would have no pain qualia, no conscious sensations of pain. This is an example of the important difference between aspects of consciousness that do and do not seem “present.” The philosophically puzzling states are the ones that seem thus-there-now, and zombies don’t have them.

I’ll allow a few days for comments about these hypothetical organisms, and then journey further into zombieland.

Roger Christan Schriner

*David Chalmers, The Conscious Mind. (Oxford: Oxford University Press), p. 95. Technical note: Chalmers was suggesting that there is an ontological gap between conscious experiences and brain states, not just the sort of epistemic gap that Joseph Levine has discussed. In other words, qualia and brain states don’t just seem different; they really are quite different. In this way Chalmers was following in the footsteps of Saul Kripke, whereas Levine was trying to avoid Kripke’s ontological conclusions.

**Philip Goff, “The Zombie Threat to a Science of Mind,” Philosophy Now, May/June, 2013: Goff provides an engaging and detailed explanation of the zombie problem, graced with charming color illustrations of non-philosophical zombies.


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